server: init functional tests (#5566)

* server: tests: init scenarios
 - health and slots endpoints
 - completion endpoint
 - OAI compatible chat completion requests w/ and without streaming
 - completion multi users scenario
 - multi users scenario on OAI compatible endpoint with streaming
 - multi users with total number of tokens to predict exceeds the KV Cache size
 - server wrong usage scenario, like in Infinite loop of "context shift" #3969
 - slots shifting
 - continuous batching
 - embeddings endpoint
 - multi users embedding endpoint: Segmentation fault #5655
 - OpenAI-compatible embeddings API
 - tokenize endpoint
 - CORS and api key scenario

* server: CI GitHub workflow


---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

14 files changed, 1243 insertions, 18 deletions

diff --git a/.github/ISSUE_TEMPLATE/bug.md b/.github/ISSUE_TEMPLATE/bug.md
index ce69e639..49812832 100644
--- a/.github/ISSUE_TEMPLATE/bug.md
+++ b/.github/ISSUE_TEMPLATE/bug.md
@@ -7,3 +7,5 @@ assignees: ''
 ---
 
 Please include information about your system, the steps to reproduce the bug, and the version of llama.cpp that you are using. If possible, please provide a minimal code example that reproduces the bug.
+
+If the bug concerns the server, please try to reproduce it first using the [server test scenario framework](https://github.com/ggerganov/llama.cpp/tree/master/examples/server/tests).
diff --git a/.github/workflows/server.yml b/.github/workflows/server.yml
new file mode 100644
index 00000000..ed27dc52
--- /dev/null
+++ b/.github/workflows/server.yml
@@ -0,0 +1,127 @@
+# Server build and tests
+name: Server
+
+on:
+  workflow_dispatch: # allows manual triggering
+  push:
+    branches:
+      - master
+      - test/server-add-ci-test # FIXME remove
+    paths: ['.github/workflows/**', '**/CMakeLists.txt', '**/Makefile', '**/*.h', '**/*.hpp', '**/*.c', '**/*.cpp', '**/*.cu', '**/*.swift', '**/*.m', 'examples/server/**.*']
+  pull_request:
+    types: [opened, synchronize, reopened]
+    paths: ['**/CMakeLists.txt', '**/Makefile', '**/*.h', '**/*.hpp', '**/*.c', '**/*.cpp', '**/*.cu', '**/*.swift', '**/*.m', 'examples/server/**.*']
+
+jobs:
+  server:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        build: [noavx, avx2, avx, avx512, cublas, clblast, openblas, kompute, vulkan]
+        sanitizer: [ADDRESS, THREAD, UNDEFINED]
+        build_type: [Debug, Release]
+        include:
+          - build: 'noavx'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_AVX=OFF -DLLAMA_AVX2=OFF -DLLAMA_FMA=OFF'
+            image: ubuntu:latest
+          - build: 'avx2'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON'
+            image: ubuntu:latest
+          - build: 'avx'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_AVX2=OFF'
+            image: ubuntu:latest
+          - build: 'avx512'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_AVX512=ON'
+            image: ubuntu:latest
+            experimental: true
+          - build: 'cublas'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_CUBLAS=ON'
+            image: nvidia/cuda:12.3.1-devel-ubuntu22.04
+            arch_not_available: true # require nvidia docker engine
+          - build: 'clblast'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_CLBLAST=ON'
+            image: ubuntu:latest
+            arch_not_available: true
+          - build: 'openblas'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_BLAS=ON -DLLAMA_BLAS_VENDOR=OpenBLAS'
+            image: ubuntu:latest
+          - build: 'kompute'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_KOMPUTE=ON -DKOMPUTE_OPT_DISABLE_VULKAN_VERSION_CHECK=ON'
+            image: ubuntu:latest
+            arch_not_available: true
+          - build: 'vulkan'
+            defines: '-DLLAMA_NATIVE=OFF -DLLAMA_BUILD_SERVER=ON -DLLAMA_VULKAN=ON'
+            image: ubuntu:latest
+            arch_not_available: true
+
+    container:
+      image: ${{ matrix.image }}
+      ports:
+        - 8888
+      options: --cpus 4
+
+    steps:
+      - name: Clone
+        id: checkout
+        uses: actions/checkout@v3
+
+      - name: Dependencies
+        id: depends
+        run: |
+          apt-get update
+          apt-get -y install \
+            build-essential \
+            pkg-config \
+            git \
+            cmake \
+            python3-pip \
+            wget \
+            psmisc
+
+      - name: Download CLBlast
+        id: get_clblast
+        if: ${{ matrix.build == 'clblast' }}
+        run: |
+          apt install -y libclblast-dev
+
+      - name: Download OpenBLAS
+        id: get_openblas
+        if: ${{ matrix.build == 'openblas' }}
+        run: |
+          apt-get -y install libopenblas-dev
+
+      - name: Install Vulkan SDK
+        id: get_vulkan
+        if: ${{ matrix.build == 'kompute' || matrix.build == 'vulkan' }}
+        run: |
+          wget -qO- https://packages.lunarg.com/lunarg-signing-key-pub.asc | tee /etc/apt/trusted.gpg.d/lunarg.asc
+          wget -qO /etc/apt/sources.list.d/lunarg-vulkan-jammy.list http://packages.lunarg.com/vulkan/lunarg-vulkan-jammy.list
+          apt-get update
+          apt-get -y install vulkan-sdk
+
+      - name: Build
+        id: cmake_build
+        run: |
+          mkdir build
+          cd build
+          cmake .. -DLLAMA_SANITIZE_${{ matrix.sanitizer }}=ON -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} ${{ matrix.defines }}
+          cmake --build . --config ${{ matrix.build_type }} -j $(nproc) --target server
+
+      - name: Tests dependencies
+        id: test_dependencies
+        run: |
+          pip install -r examples/server/tests/requirements.txt
+
+      - name: Download models
+        id: download_models
+        run: |
+          cd examples/server/tests
+          ../../../scripts/hf.sh --repo ggml-org/models --file tinyllamas/stories260K.gguf
+
+      - name: Tests
+        id: server_integration_test
+        continue-on-error: ${{ matrix.experimental || matrix.arch_not_available }}
+        run: |
+          cd examples/server/tests
+          PORT=8888 ./tests.sh
diff --git a/examples/server/README.md b/examples/server/README.md
index 4b6cd832..0c43ac4c 100644
--- a/examples/server/README.md
+++ b/examples/server/README.md
@@ -98,6 +98,12 @@ curl --request POST \
     --data '{"prompt": "Building a website can be done in 10 simple steps:","n_predict": 128}'
 ```
 
+## Advanced testing
+
+We implemented a [server test framework](./tests/README.md) using human-readable scenario.
+
+*Before submitting an issue, please try to reproduce it with this format.*
+
 ## Node JS Test
 
 You need to have [Node.js](https://nodejs.org/en) installed.
diff --git a/examples/server/server.cpp b/examples/server/server.cpp
index 524d0ada..9fb436c2 100644
--- a/examples/server/server.cpp
+++ b/examples/server/server.cpp
@@ -1410,11 +1410,6 @@ struct llama_server_context
                 int n_processing_slots = 0;
 
                 for (llama_client_slot &slot: slots) {
-                    if (slot.available()) {
-                        n_idle_slots++;
-                    } else {
-                        n_processing_slots++;
-                    }
                     json slot_data = get_formated_generation(slot);
                     slot_data["id"] = slot.id;
                     slot_data["task_id"] = slot.task_id;
@@ -1429,6 +1424,11 @@ struct llama_server_context
                             {"stopped_limit", slot.stopped_limit},
                             {"stopping_word", slot.stopping_word},
                     };
+                    if (slot_data["state"] == IDLE) {
+                        n_idle_slots++;
+                    } else {
+                        n_processing_slots++;
+                    }
                     slots_data.push_back(slot_data);
                 }
                 LOG_TEE("task %i - slots data: idle=%i processing=%i\n", task.id, n_idle_slots, n_processing_slots);
@@ -2748,19 +2748,6 @@ int main(int argc, char **argv)
         log_data["api_key"] = "api_key: " + std::to_string(sparams.api_keys.size()) + " keys loaded";
     }
 
-    LOG_INFO("HTTP server listening", log_data);
-    // run the HTTP server in a thread - see comment below
-    std::thread t([&]()
-            {
-                if (!svr.listen_after_bind())
-                {
-                    state.store(SERVER_STATE_ERROR);
-                    return 1;
-                }
-
-                return 0;
-            });
-
     // load the model
     if (!llama.load_model(params))
     {
@@ -3228,6 +3215,19 @@ int main(int argc, char **argv)
     }*/
     //);
 
+    LOG_INFO("HTTP server listening", log_data);
+    // run the HTTP server in a thread - see comment below
+    std::thread t([&]()
+            {
+                if (!svr.listen_after_bind())
+                {
+                    state.store(SERVER_STATE_ERROR);
+                    return 1;
+                }
+
+                return 0;
+            });
+
     llama.queue_tasks.on_new_task(std::bind(
         &llama_server_context::process_single_task, &llama, std::placeholders::_1));
     llama.queue_tasks.on_finish_multitask(std::bind(
diff --git a/examples/server/tests/README.md b/examples/server/tests/README.md
new file mode 100644
index 00000000..e44c5c28
--- /dev/null
+++ b/examples/server/tests/README.md
@@ -0,0 +1,46 @@
+# Server tests
+
+Python based server tests scenario using [BDD](https://en.wikipedia.org/wiki/Behavior-driven_development) and [behave](https://behave.readthedocs.io/en/latest/):
+ * [issues.feature](./features/issues.feature) Pending issues scenario
+ * [parallel.feature](./features/parallel.feature) Scenario involving multi slots and concurrent requests
+ * [security.feature](./features/security.feature) Security, CORS and API Key
+ * [server.feature](./features/server.feature) Server base scenario: completion, embedding, tokenization, etc...
+
+Tests target GitHub workflows job runners with 4 vCPU.
+
+Requests are using [aiohttp](https://docs.aiohttp.org/en/stable/client_reference.html), [asyncio](https://docs.python.org/fr/3/library/asyncio.html) based http client.
+
+Note: If the host architecture inference speed is faster than GitHub runners one, parallel scenario may randomly fail. To mitigate it, you can increase values in `n_predict`, `kv_size`.
+
+### Install dependencies
+`pip install -r requirements.txt`
+
+### Run tests
+1. Build the server
+```shell
+cd ../../..
+mkdir build
+cd build
+cmake ../
+cmake --build . --target server
+```
+2. download required models:
+   1. `../../../scripts/hf.sh --repo ggml-org/models --file tinyllamas/stories260K.gguf`
+3. Start the test: `./tests.sh`
+
+It's possible to override some scenario steps values with environment variables:
+ - `PORT` -> `context.server_port` to set the listening port of the server during scenario, default: `8080`
+ - `LLAMA_SERVER_BIN_PATH` -> to change the server binary path, default: `../../../build/bin/server`
+ - `DEBUG` -> "ON" to enable steps and server verbose mode `--verbose`
+
+### Run @bug, @wip or @wrong_usage annotated scenario
+
+Feature or Scenario must be annotated with `@llama.cpp` to be included in the default scope.
+- `@bug` annotation aims to link a scenario with a GitHub issue.
+- `@wrong_usage` are meant to show user issue that are actually an expected behavior
+- `@wip` to focus on a scenario working in progress
+
+To run a scenario annotated with `@bug`, start:
+`DEBUG=ON ./tests.sh --no-skipped --tags bug`
+
+After changing logic in `steps.py`, ensure that `@bug` and `@wrong_usage` scenario are updated.
diff --git a/examples/server/tests/features/environment.py b/examples/server/tests/features/environment.py
new file mode 100644
index 00000000..13cc8410
--- /dev/null
+++ b/examples/server/tests/features/environment.py
@@ -0,0 +1,67 @@
+import os
+import socket
+import subprocess
+import time
+from contextlib import closing
+from signal import SIGKILL
+
+
+def before_scenario(context, scenario):
+    print(f"\x1b[33;42mStarting new scenario: {scenario.name}!\x1b[0m")
+    port = 8080
+    if 'PORT' in os.environ:
+        port = int(os.environ['PORT'])
+    if is_server_listening("localhost", port):
+        assert False, "Server already started"
+
+
+def after_scenario(context, scenario):
+    if scenario.status == "failed":
+        if 'GITHUB_ACTIONS' in os.environ:
+            print(f"\x1b[33;101mSCENARIO FAILED: {scenario.name} server logs:\x1b[0m\n\n")
+            if os.path.isfile('llama.log'):
+                with closing(open('llama.log', 'r')) as f:
+                    for line in f:
+                        print(line)
+        if not is_server_listening(context.server_fqdn, context.server_port):
+            print("\x1b[33;101mERROR: Server stopped listening\x1b[0m")
+
+    if not pid_exists(context.server_process.pid):
+        assert False, f"Server not running pid={context.server_process.pid} ..."
+
+    print(f"stopping server pid={context.server_process.pid} ...")
+    context.server_process.kill()
+    # Wait few for socket to free up
+    time.sleep(0.05)
+
+    attempts = 0
+    while is_server_listening(context.server_fqdn, context.server_port):
+        print(f"stopping server pid={context.server_process.pid} ...")
+        os.kill(context.server_process.pid, SIGKILL)
+        time.sleep(0.1)
+        attempts += 1
+        if attempts > 5:
+            print(f"Server dangling exits, killing all {context.server_path} ...")
+            process = subprocess.run(['killall', '-9', context.server_path],
+                                     stderr=subprocess.PIPE,
+                                     universal_newlines=True)
+            print(process)
+
+
+def is_server_listening(server_fqdn, server_port):
+    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
+        result = sock.connect_ex((server_fqdn, server_port))
+        return result == 0
+
+
+def pid_exists(pid):
+    """Check whether pid exists in the current process table."""
+    import errno
+    if pid < 0:
+        return False
+    try:
+        os.kill(pid, 0)
+    except OSError as e:
+        return e.errno == errno.EPERM
+    else:
+        return True
diff --git a/examples/server/tests/features/issues.feature b/examples/server/tests/features/issues.feature
new file mode 100644
index 00000000..542006d9
--- /dev/null
+++ b/examples/server/tests/features/issues.feature
@@ -0,0 +1,36 @@
+# List of ongoing issues
+@bug
+Feature: Issues
+    # Issue #5655
+  Scenario: Multi users embeddings
+    Given a server listening on localhost:8080
+    And   a model file stories260K.gguf
+    And   a model alias tinyllama-2
+    And   42 as server seed
+    And   64 KV cache size
+    And   2 slots
+    And   continuous batching
+    And   embeddings extraction
+    Then  the server is starting
+    Then  the server is healthy
+
+    Given a prompt:
+      """
+      Write a very long story about AI.
+      """
+    And a prompt:
+      """
+      Write another very long music lyrics.
+      """
+    And a prompt:
+      """
+      Write a very long poem.
+      """
+    And a prompt:
+      """
+      Write a very long joke.
+      """
+    Given concurrent embedding requests
+    Then the server is busy
+    Then the server is idle
+    Then all embeddings are generated
diff --git a/examples/server/tests/features/parallel.feature b/examples/server/tests/features/parallel.feature
new file mode 100644
index 00000000..802d624f
--- /dev/null
+++ b/examples/server/tests/features/parallel.feature
@@ -0,0 +1,77 @@
+@llama.cpp
+Feature: Parallel
+
+  Background: Server startup
+    Given a server listening on localhost:8080
+    And   a model file stories260K.gguf
+    And   a model alias tinyllama-2
+    And   42 as server seed
+    And   64 KV cache size
+    And   2 slots
+    And   continuous batching
+    Then  the server is starting
+    Then  the server is healthy
+
+  Scenario Outline: Multi users completion
+    Given a prompt:
+      """
+      Write a very long story about AI.
+      """
+    And a prompt:
+      """
+      Write another very long music lyrics.
+      """
+    And <n_predict> max tokens to predict
+    Given concurrent completion requests
+    Then the server is busy
+    Then the server is idle
+    And  all slots are idle
+    Then all prompts are predicted with <n_predict> tokens
+    Examples:
+      | n_predict |
+      | 128       |
+
+  Scenario Outline: Multi users OAI completions compatibility
+    Given a system prompt You are a writer.
+    And   a model tinyllama-2
+    Given a prompt:
+      """
+      Write a very long book.
+      """
+    And a prompt:
+      """
+      Write another a poem.
+      """
+    And <n_predict> max tokens to predict
+    And streaming is <streaming>
+    Given concurrent OAI completions requests
+    Then the server is busy
+    Then the server is idle
+    Then all prompts are predicted with <n_predict> tokens
+    Examples:
+      | streaming | n_predict |
+      | disabled  | 128       |
+      | enabled   | 64        |
+
+  Scenario:  Multi users with total number of tokens to predict exceeds the KV Cache size #3969
+    Given a prompt:
+      """
+      Write a very long story about AI.
+      """
+    And a prompt:
+      """
+      Write another very long music lyrics.
+      """
+    And a prompt:
+      """
+      Write a very long poem.
+      """
+    And a prompt:
+      """
+      Write a very long joke.
+      """
+    And 128 max tokens to predict
+    Given concurrent completion requests
+    Then the server is busy
+    Then the server is idle
+    Then all prompts are predicted
diff --git a/examples/server/tests/features/security.feature b/examples/server/tests/features/security.feature
new file mode 100644
index 00000000..db06d397
--- /dev/null
+++ b/examples/server/tests/features/security.feature
@@ -0,0 +1,50 @@
+@llama.cpp
+Feature: Security
+
+  Background: Server startup with an api key defined
+    Given a server listening on localhost:8080
+    And   a model file stories260K.gguf
+    And   a server api key llama.cpp
+    Then  the server is starting
+    Then  the server is healthy
+
+  Scenario Outline: Completion with some user api key
+    Given a prompt test
+    And   a user api key <api_key>
+    And   4 max tokens to predict
+    And   a completion request with <api_error> api error
+
+    Examples: Prompts
+      | api_key   | api_error |
+      | llama.cpp | no        |
+      | llama.cpp | no        |
+      | hackeme   | raised    |
+      |           | raised    |
+
+  Scenario Outline: OAI Compatibility
+    Given a system prompt test
+    And   a user prompt test
+    And   a model test
+    And   2 max tokens to predict
+    And   streaming is disabled
+    And   a user api key <api_key>
+    Given an OAI compatible chat completions request with <api_error> api error
+
+    Examples: Prompts
+      | api_key   | api_error |
+      | llama.cpp | no        |
+      | llama.cpp | no        |
+      | hackme    | raised    |
+
+
+  Scenario Outline: CORS Options
+    When an OPTIONS request is sent from <origin>
+    Then CORS header <cors_header> is set to <cors_header_value>
+
+    Examples: Headers
+      | origin          | cors_header                      | cors_header_value |
+      | localhost       | Access-Control-Allow-Origin      | localhost         |
+      | web.mydomain.fr | Access-Control-Allow-Origin      | web.mydomain.fr   |
+      | origin          | Access-Control-Allow-Credentials | true              |
+      | web.mydomain.fr | Access-Control-Allow-Methods     | POST              |
+      | web.mydomain.fr | Access-Control-Allow-Headers     | *                 |
diff --git a/examples/server/tests/features/server.feature b/examples/server/tests/features/server.feature
new file mode 100644
index 00000000..fedcfe5a
--- /dev/null
+++ b/examples/server/tests/features/server.feature
@@ -0,0 +1,69 @@
+@llama.cpp
+Feature: llama.cpp server
+
+  Background: Server startup
+    Given a server listening on localhost:8080
+    And   a model file stories260K.gguf
+    And   a model alias tinyllama-2
+    And   42 as server seed
+      # KV Cache corresponds to the total amount of tokens
+      # that can be stored across all independent sequences: #4130
+      # see --ctx-size and #5568
+    And   32 KV cache size
+    And   1 slots
+    And   embeddings extraction
+    And   32 server max tokens to predict
+    Then  the server is starting
+    Then  the server is healthy
+
+  Scenario: Health
+    Then the server is ready
+    And  all slots are idle
+
+  Scenario Outline: Completion
+    Given a prompt <prompt>
+    And   <n_predict> max tokens to predict
+    And   a completion request with no api error
+    Then  <n_predicted> tokens are predicted matching <re_content>
+
+    Examples: Prompts
+      | prompt                           | n_predict | re_content                   | n_predicted |
+      | I believe the meaning of life is | 8         | read                         | 8           |
+      | Write a joke about AI            | 64        | (park<or>friends<or>scared)+ | 32          |
+
+  Scenario Outline: OAI Compatibility
+    Given a model <model>
+    And   a system prompt <system_prompt>
+    And   a user prompt <user_prompt>
+    And   <max_tokens> max tokens to predict
+    And   streaming is <enable_streaming>
+    Given an OAI compatible chat completions request with no api error
+    Then  <n_predicted> tokens are predicted matching <re_content>
+
+    Examples: Prompts
+      | model        | system_prompt               | user_prompt                          | max_tokens | re_content                 | n_predicted | enable_streaming |
+      | llama-2      | Book                        | What is the best book                | 8          | (Mom<or>what)+             | 8           | disabled         |
+      | codellama70b | You are a coding assistant. | Write the fibonacci function in c++. | 64         | (thanks<or>happy<or>bird)+ | 32          | enabled          |
+
+  Scenario: Embedding
+    When embeddings are computed for:
+    """
+    What is the capital of Bulgaria ?
+    """
+    Then embeddings are generated
+
+  Scenario: OAI Embeddings compatibility
+    Given a model tinyllama-2
+    When an OAI compatible embeddings computation request for:
+    """
+    What is the capital of Spain ?
+    """
+    Then embeddings are generated
+
+
+  Scenario: Tokenize / Detokenize
+    When tokenizing:
+    """
+    What is the capital of France ?
+    """
+    Then tokens can be detokenize
diff --git a/examples/server/tests/features/steps/steps.py b/examples/server/tests/features/steps/steps.py
new file mode 100644
index 00000000..50f2b641
--- /dev/null
+++ b/examples/server/tests/features/steps/steps.py
@@ -0,0 +1,709 @@
+import asyncio
+import json
+import os
+import re
+import socket
+import subprocess
+import time
+from contextlib import closing
+from re import RegexFlag
+
+import aiohttp
+import openai
+from behave import step
+from behave.api.async_step import async_run_until_complete
+
+
+@step(u"a server listening on {server_fqdn}:{server_port}")
+def step_server_config(context, server_fqdn, server_port):
+    context.server_fqdn = server_fqdn
+    context.server_port = int(server_port)
+    if 'PORT' in os.environ:
+        context.server_port = int(os.environ['PORT'])
+        print(f"$PORT set, overriding server port with to {context.server_port}")
+
+    context.base_url = f'http://{context.server_fqdn}:{context.server_port}'
+
+    context.debug = 'DEBUG' in os.environ and os.environ['DEBUG'] == 'ON'
+    context.model_alias = None
+    context.n_ctx = None
+    context.n_predict = None
+    context.n_server_predict = None
+    context.n_slots = None
+    context.server_api_key = None
+    context.server_continuous_batching = False
+    context.server_embeddings = False
+    context.server_seed = None
+    context.user_api_key = None
+
+    context.tasks_result = []
+    context.concurrent_tasks = []
+    context.prompts = []
+
+
+@step(u'a model file {model_file}')
+def step_model_file(context, model_file):
+    context.model_file = model_file
+
+
+@step(u'a model alias {model_alias}')
+def step_model_alias(context, model_alias):
+    context.model_alias = model_alias
+
+
+@step(u'{seed} as server seed')
+def step_seed(context, seed):
+    context.server_seed = int(seed)
+
+
+@step(u'{n_ctx} KV cache size')
+def step_n_ctx(context, n_ctx):
+    context.n_ctx = int(n_ctx)
+
+
+@step(u'{n_slots} slots')
+def step_n_slots(context, n_slots):
+    context.n_slots = int(n_slots)
+
+
+@step(u'{n_predict} server max tokens to predict')
+def step_server_n_predict(context, n_predict):
+    context.n_server_predict = int(n_predict)
+
+
+@step(u'continuous batching')
+def step_server_continuous_batching(context):
+    context.server_continuous_batching = True
+
+
+@step(u'embeddings extraction')
+def step_server_embeddings(context):
+    context.server_embeddings = True
+
+
+@step(u"the server is starting")
+def step_start_server(context):
+    start_server_background(context)
+    attempts = 0
+    while True:
+        with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
+            result = sock.connect_ex((context.server_fqdn, context.server_port))
+            if result == 0:
+                print("\x1b[33;46mserver started!\x1b[0m")
+                return
+            attempts += 1
+            if attempts > 20:
+                assert False, "server not started"
+            print(f"waiting for server to start, connect error code = {result}...")
+            time.sleep(0.1)
+
+
+@step(u"the server is {expecting_status}")
+@async_run_until_complete
+async def step_wait_for_the_server_to_be_started(context, expecting_status):
+    match expecting_status:
+        case 'healthy':
+            await wait_for_health_status(context, context.base_url, 200, 'ok')
+
+        case 'ready' | 'idle':
+            await wait_for_health_status(context, context.base_url, 200, 'ok',
+                                         params={'fail_on_no_slot': 0, 'include_slots': 0},
+                                         slots_idle=context.n_slots,
+                                         slots_processing=0,
+                                         expected_slots=[{'id': slot_id, 'state': 0}
+                                                         for slot_id in range(context.n_slots)])
+        case 'busy':
+            await wait_for_health_status(context, context.base_url, 503,
+                                         'no slot available',
+                                         params={'fail_on_no_slot': 0, 'include_slots': 0},
+                                         slots_idle=0,
+                                         slots_processing=context.n_slots,
+                                         expected_slots=[{'id': slot_id, 'state': 1}
+                                                         for slot_id in range(context.n_slots)])
+        case _:
+            assert False, "unknown status"
+
+
+@step(u'all slots are {expected_slot_status_string}')
+@async_run_until_complete
+async def step_all_slots_status(context, expected_slot_status_string):
+    match expected_slot_status_string:
+        case 'idle':
+            expected_slot_status = 0
+        case 'busy':
+            expected_slot_status = 1
+        case _:
+            assert False, "unknown status"
+
+    expected_slots = [{'id': slot_id, 'state': expected_slot_status}
+                      for slot_id in range(context.n_slots)]
+    await request_slots_status(context, expected_slots)
+
+
+@step(u'a completion request with {api_error} api error')
+@async_run_until_complete
+async def step_request_completion(context, api_error):
+    expect_api_error = api_error == 'raised'
+    completion = await request_completion(context.prompts.pop(),
+                                          context.base_url,
+                                          debug=context.debug,
+                                          n_predict=context.n_predict,
+                                          server_seed=context.server_seed,
+                                          expect_api_error=expect_api_error,
+                                          user_api_key=context.user_api_key)
+    context.tasks_result.append(completion)
+    if context.debug:
+        print(f"Completion response: {completion}")
+    if expect_api_error:
+        assert completion == 401, f"completion must be an 401 status code: {completion}"
+
+
+@step(u'{predicted_n} tokens are predicted matching {re_content}')
+def step_n_tokens_predicted_with_content(context, predicted_n, re_content):
+    assert_n_tokens_predicted(context.tasks_result.pop(), int(predicted_n), re_content)
+
+
+@step(u'{predicted_n} tokens are predicted')
+def step_n_tokens_predicted(context, predicted_n):
+    assert_n_tokens_predicted(context.tasks_result.pop(), int(predicted_n))
+
+
+@step(u'a user prompt {user_prompt}')
+def step_user_prompt(context, user_prompt):
+    context.prompts.append(user_prompt)
+
+
+@step(u'a system prompt {system_prompt}')
+def step_system_prompt(context, system_prompt):
+    context.system_prompt = system_prompt
+
+
+@step(u'a model {model}')
+def step_model(context, model):
+    context.model = model
+
+
+@step(u'{max_tokens} max tokens to predict')
+def step_max_tokens(context, max_tokens):
+    context.n_predict = int(max_tokens)
+
+
+@step(u'streaming is {enable_streaming}')
+def step_streaming(context, enable_streaming):
+    context.enable_streaming = enable_streaming == 'enabled'
+
+
+@step(u'a user api key {user_api_key}')
+def step_user_api_key(context, user_api_key):
+    context.user_api_key = user_api_key
+
+
+@step(u'no user api key')
+def step_no_user_api_key(context):
+    context.user_api_key = None
+
+
+@step(u'a user api key ')
+def step_no_user_api_key_space(context):
+    context.user_api_key = None
+
+
+@step(u'a server api key {server_api_key}')
+def step_server_api_key(context, server_api_key):
+    context.server_api_key = server_api_key
+
+
+@step(u'an OAI compatible chat completions request with {api_error} api error')
+@async_run_until_complete
+async def step_oai_chat_completions(context, api_error):
+    if context.debug:
+        print(f"Submitting OAI compatible completions request...")
+    expect_api_error = api_error == 'raised'
+    completion = await oai_chat_completions(context.prompts.pop(),
+                                            context.system_prompt,
+                                            context.base_url,
+                                            False,
+                                            model=context.model if hasattr(context, 'model') else None,
+
+                                            n_predict=context.n_predict
+                                            if hasattr(context, 'n_predict') else None,
+
+                                            enable_streaming=context.enable_streaming
+                                            if hasattr(context, 'enable_streaming') else None,
+
+                                            server_seed=context.server_seed
+                                            if hasattr(context, 'server_seed') else None,
+
+                                            user_api_key=context.user_api_key
+                                            if hasattr(context, 'user_api_key') else None,
+
+                                            expect_api_error=expect_api_error)
+    context.tasks_result.append(completion)
+    if context.debug:
+        print(f"Completion response: {completion}")
+    if expect_api_error:
+        assert completion == 401, f"completion must be an 401 status code: {completion}"
+
+    if context.debug:
+        print(f"Completion response: {completion}")
+
+
+@step(u'a prompt')
+def step_a_prompt(context):
+    context.prompts.append(context.text)
+
+
+@step(u'a prompt {prompt}')
+def step_a_prompt_prompt(context, prompt):
+    context.prompts.append(prompt)
+
+
+@step(u'concurrent completion requests')
+@async_run_until_complete()
+async def step_concurrent_completion_requests(context):
+    await concurrent_completion_requests(context,
+                                         request_completion,
+                                         # prompt is inserted automatically
+                                         context.base_url,
+                                         debug=context.debug,
+                                         n_predict=context.n_predict if hasattr(context, 'n_predict') else None,
+                                         server_seed=context.server_seed if hasattr(context, 'server_seed') else None,
+                                         user_api_key=context.user_api_key if hasattr(context,
+                                                                                      'user_api_key') else None)
+
+
+@step(u'concurrent OAI completions requests')
+@async_run_until_complete
+async def step_oai_chat_completions(context):
+    await concurrent_completion_requests(context, oai_chat_completions,
+                                         # user_prompt is inserted automatically
+                                         context.system_prompt,
+                                         context.base_url,
+                                         True,  # async_client
+                                         model=context.model
+                                         if hasattr(context, 'model') else None,
+                                         n_predict=context.n_predict
+                                         if hasattr(context, 'n_predict') else None,
+                                         enable_streaming=context.enable_streaming
+                                         if hasattr(context, 'enable_streaming') else None,
+                                         server_seed=context.server_seed
+                                         if hasattr(context, 'server_seed') else None,
+                                         user_api_key=context.user_api_key
+                                         if hasattr(context, 'user_api_key') else None)
+
+
+@step(u'all prompts are predicted')
+@async_run_until_complete
+async def step_all_prompts_are_predicted(context):
+    await all_prompts_are_predicted(context)
+
+
+@step(u'all prompts are predicted with {n_predict} tokens')
+@async_run_until_complete
+async def step_all_prompts_are_predicted_with_n_tokens(context, n_predict):
+    expected_predicted_n = int(n_predict)
+    await all_prompts_are_predicted(context, expected_predicted_n)
+
+
+async def all_prompts_are_predicted(context, expected_predicted_n=None):
+    n_completions = await gather_tasks_results(context)
+    assert n_completions > 0
+    for i in range(n_completions):
+        assert_n_tokens_predicted(context.tasks_result.pop(), expected_predicted_n=expected_predicted_n)
+    assert len(context.concurrent_tasks) == 0, f"{len(context.concurrent_tasks)} pending requests"
+
+
+@step(u'embeddings are computed for')
+@async_run_until_complete
+async def step_compute_embedding(context):
+    content = context.text
+    base_url = context.base_url
+    context.embeddings = await request_embedding(content, base_url)
+
+
+@step(u'embeddings are generated')
+def step_assert_embeddings(context):
+    assert_embeddings(context.embeddings)
+
+
+@step(u'an OAI compatible embeddings computation request for')
+def step_oai_compute_embedding(context):
+    openai.api_key = 'nope'  # openai client always expects an api_keu
+    if context.user_api_key is not None:
+        openai.api_key = context.user_api_key
+    openai.api_base = f'{context.base_url}/v1'
+    embeddings = openai.Embedding.create(
+        model=context.model,
+        input=context.text,
+    )
+    context.embeddings = embeddings
+
+
+@step(u'concurrent embedding requests')
+@async_run_until_complete()
+async def step_concurrent_embedding_requests(context):
+    await concurrent_completion_requests(context,
+                                         request_embedding,
+                                         # prompt is inserted automatically
+                                         context.base_url)
+
+
+@step(u'all embeddings are generated')
+@async_run_until_complete()
+async def all_embeddings_are_generated(context):
+    n_embedding_requests = await gather_tasks_results(context)
+    assert n_embedding_requests > 0
+    for i in range(n_embedding_requests):
+        assert_embeddings(context.tasks_result.pop())
+
+
+@step(u'tokenizing')
+@async_run_until_complete
+async def step_tokenize(context):
+    context.tokenized_text = context.text
+    async with aiohttp.ClientSession() as session:
+        async with session.post(f'{context.base_url}/tokenize',
+                                json={
+                                    "content": context.tokenized_text,
+                                }) as response:
+            assert response.status == 200
+            tokenize_json = await response.json()
+            context.tokens = tokenize_json['tokens']
+
+
+@step(u'tokens can be detokenize')
+@async_run_until_complete
+async def step_detokenize(context):
+    assert len(context.tokens) > 0
+    async with aiohttp.ClientSession() as session:
+        async with session.post(f'{context.base_url}/detokenize',
+                                json={
+                                    "tokens": context.tokens,
+                                }) as response:
+            assert response.status == 200
+            detokenize_json = await response.json()
+            # SPM tokenizer adds a whitespace prefix: https://github.com/google/sentencepiece/issues/15
+            assert context.tokenized_text == detokenize_json['content'].strip()
+
+
+@step(u'an OPTIONS request is sent from {origin}')
+@async_run_until_complete
+async def step_options_request(context, origin):
+    async with aiohttp.ClientSession() as session:
+        async with session.options(f'{context.base_url}/v1/chat/completions',
+                                   headers={"Origin": origin}) as response:
+            assert response.status == 200
+            context.options_response = response
+
+
+@step(u'CORS header {cors_header} is set to {cors_header_value}')
+def step_check_options_header_value(context, cors_header, cors_header_value):
+    assert context.options_response.headers[cors_header] == cors_header_value
+
+
+async def concurrent_completion_requests(context, f_completion, *args, **kwargs):
+    n_prompts = len(context.prompts)
+    if context.debug:
+        print(f"starting {n_prompts} concurrent completion requests...")
+    assert n_prompts > 0
+    for prompt_no in range(n_prompts):
+        shifted_args = [context.prompts.pop(), *args]
+        context.concurrent_tasks.append(asyncio.create_task(f_completion(*shifted_args, **kwargs)))
+    await asyncio.sleep(0.1)
+
+
+async def request_completion(prompt,
+                             base_url,
+                             debug=False,
+                             n_predict=None,
+                             server_seed=None,
+                             expect_api_error=None,
+                             user_api_key=None):
+    if debug:
+        print(f"Sending completion request: {prompt}")
+    origin = "my.super.domain"
+    headers = {
+        'Origin': origin
+    }
+    if user_api_key is not None:
+        if debug:
+            print(f"Set user_api_key: {user_api_key}")
+        headers['Authorization'] = f'Bearer {user_api_key}'
+
+    async with aiohttp.ClientSession() as session:
+        async with session.post(f'{base_url}/completion',
+                                json={
+                                    "prompt": prompt,
+                                    "n_predict": int(n_predict) if n_predict is not None else -1,
+                                    "seed": server_seed if server_seed is not None else 42
+                                },
+                                headers=headers) as response:
+            if expect_api_error is None or not expect_api_error:
+                assert response.status == 200
+                assert response.headers['Access-Control-Allow-Origin'] == origin
+                return await response.json()
+            else:
+                return response.status
+
+
+async def oai_chat_completions(user_prompt,
+                               system_prompt,
+                               base_url,
+                               async_client,
+                               debug=False,
+                               model=None,
+                               n_predict=None,
+                               enable_streaming=None,
+                               server_seed=None,
+                               user_api_key=None,
+                               expect_api_error=None):
+    if debug:
+        print(f"Sending OAI Chat completions request: {user_prompt}")
+    # openai client always expects an api key
+    user_api_key = user_api_key if user_api_key is not None else 'nope'
+    seed = server_seed if server_seed is not None else 42
+    enable_streaming = enable_streaming if enable_streaming is not None else False
+    payload = {
+        "messages": [
+            {
+                "role": "system",
+                "content": system_prompt,
+            },
+            {
+                "role": "user",
+                "content": user_prompt,
+            }
+        ],
+        "model": model,
+        "max_tokens": n_predict,
+        "stream": enable_streaming,
+        "seed": seed
+    }
+    completion_response = {
+        'content': '',
+        'timings': {
+            'predicted_n': 0
+        }
+    }
+    if async_client:
+        origin = 'llama.cpp'
+        headers = {'Authorization': f'Bearer {user_api_key}', 'Origin': origin}
+        async with aiohttp.ClientSession() as session:
+            async with session.post(f'{base_url}/v1/chat/completions',
+                                    json=payload,
+                                    headers=headers) as response:
+                if enable_streaming:
+                    assert response.status == 200
+                    assert response.headers['Access-Control-Allow-Origin'] == origin
+                    assert response.headers['Content-Type'] == "text/event-stream"
+                    event_received = True
+                    while event_received:
+                        event_received = False
+                        async for line_in_bytes in response.content:
+                            line = line_in_bytes.decode('utf8')
+                            line = line.rstrip('\n').rstrip('\r')
+                            if line == '':
+                                continue
+                            event_data = line.split(': ', 1)
+                            assert event_data[0] == 'data', f'Bad event code received: ```{event_data}```'
+                            chunk_raw = event_data[1]
+
+                            chunk = json.loads(chunk_raw)
+                            assert len(chunk['choices']) == 1, f"no choices provided, line ```{line}```"
+                            delta = chunk['choices'][0]['delta']
+                            if 'content' in delta:
+                                completion_response['content'] += delta['content']
+                                completion_response['timings']['predicted_n'] += 1
+                else:
+                    if expect_api_error is None or not expect_api_error:
+                        assert response.status == 200
+                        assert response.headers['Access-Control-Allow-Origin'] == origin
+                        assert response.headers['Content-Type'] == "application/json; charset=utf-8"
+                        chat_completion_raw = await response.json()
+                        completion_response = {
+                            'content': chat_completion_raw['choices'][0]['message'],
+                            'timings': {
+                                'predicted_n': chat_completion_raw['usage']['completion_tokens']
+                            }
+                        }
+                    else:
+                        return response.status
+    else:
+        try:
+            openai.api_key = user_api_key
+            openai.api_base = f'{base_url}/v1/chat'
+            chat_completion = openai.Completion.create(
+                messages=payload['messages'],
+                model=model,
+                max_tokens=n_predict,
+                stream=enable_streaming,
+                seed=seed
+            )
+        except openai.error.APIError as e:
+            if expect_api_error is not None and expect_api_error:
+                return 401
+            else:
+                assert False, f'error raised: {e}'
+
+        if enable_streaming:
+            for chunk in chat_completion:
+                assert len(chunk.choices) == 1
+                delta = chunk.choices[0].delta
+                if 'content' in delta:
+                    completion_response['content'] += delta['content']
+                    completion_response['timings']['predicted_n'] += 1
+        else:
+            assert len(chat_completion.choices) == 1
+            completion_response = {
+                'content': chat_completion.choices[0].message.content,
+                'timings': {
+                    'predicted_n': chat_completion.usage.completion_tokens
+                }
+            }
+    if debug:
+        print("OAI response formatted to llama.cpp:", completion_response)
+    return completion_response
+
+
+async def request_embedding(content, base_url):
+    async with aiohttp.ClientSession() as session:
+        async with session.post(f'{base_url}/embedding',
+                                json={
+                                    "content": content,
+                                }) as response:
+            assert response.status == 200
+            response_json = await response.json()
+            return response_json['embedding']
+
+
+def assert_n_tokens_predicted(completion_response, expected_predicted_n=None, re_content=None):
+    content = completion_response['content']
+    n_predicted = completion_response['timings']['predicted_n']
+    assert len(content) > 0, "no token predicted"
+    if expected_predicted_n is not None:
+        assert n_predicted == expected_predicted_n, (f'invalid number of tokens predicted:'
+                                                     f' {n_predicted} <> {expected_predicted_n}')
+    if re_content is not None:
+        re_content = '^.*' + re_content.replace('<or>', '|') + '.*$'
+        assert re.match(re_content, content, flags=RegexFlag.IGNORECASE | RegexFlag.MULTILINE | RegexFlag.DOTALL), (
+            f'invalid tokens predicted:'
+            f' ```\n{content}\n``` do not match /{re_content}/')
+
+
+async def gather_tasks_results(context):
+    n_tasks = len(context.concurrent_tasks)
+    if context.debug:
+        print(f"Waiting for all {n_tasks} tasks results...")
+    for task_no in range(n_tasks):
+        context.tasks_result.append(await context.concurrent_tasks.pop())
+    n_completions = len(context.tasks_result)
+    return n_completions
+
+
+async def wait_for_health_status(context,
+                                 base_url,
+                                 expected_http_status_code,
+                                 expected_health_status,
+                                 params=None,
+                                 slots_idle=None,
+                                 slots_processing=None,
+                                 expected_slots=None):
+    if context.debug:
+        print(f"Starting checking for health for expected_health_status={expected_health_status}")
+    timeout = 3  # seconds
+    interval = 0.5
+    counter = 0
+    async with aiohttp.ClientSession() as session:
+        while True:
+            async with await session.get(f'{base_url}/health', params=params) as health_response:
+                status_code = health_response.status
+                health = await health_response.json()
+                if context.debug:
+                    print(f"HEALTH - response for expected health status='{expected_health_status}' on "
+                          f"'{base_url}/health'?{params} is {health}")
+                if (status_code == expected_http_status_code
+                        and health['status'] == expected_health_status
+                        and (slots_idle is None or health['slots_idle'] == slots_idle)
+                        and (slots_processing is None or health['slots_processing'] == slots_processing)):
+                    if expected_slots is not None:
+                        assert_slots_status(health['slots'], expected_slots)
+                    return
+                if (status_code == expected_http_status_code
+                        and health['status'] == expected_health_status
+                        and (slots_idle is None or health['slots_idle'] == slots_idle)
+                        and (slots_processing is None or health['slots_processing'] == slots_processing)):
+                    if expected_slots is not None:
+                        assert_slots_status(health['slots'], expected_slots)
+                    return
+            await asyncio.sleep(interval)
+
+            counter += interval
+            if counter >= timeout:
+                # Sometimes health requests are triggered after completions are predicted
+                if expected_http_status_code == 503:
+                    if len(context.tasks_result) == 0:
+                        print("\x1b[5;37;43mWARNING: forcing concurrent tasks,"
+                              " busy health check missed, probably too fast inference\x1b[0m")
+                        n_completions = await gather_tasks_results(context)
+                        if n_completions > 0:
+                            return
+
+                assert False, 'timeout exceeded'
+
+
+def assert_embeddings(embeddings):
+    assert len(embeddings) > 0
+    embeddings_computed = False
+    for emb in embeddings:
+        if emb != 0:
+            embeddings_computed = True
+    assert embeddings_computed, f"Embeddings: {embeddings}"
+
+
+async def request_slots_status(context, expected_slots):
+    async with aiohttp.ClientSession() as session:
+        async with await session.get(f'{context.base_url}/slots') as slots_response:
+            assert slots_response.status == 200
+            slots = await slots_response.json()
+            assert_slots_status(slots, expected_slots)
+
+
+def assert_slots_status(slots, expected_slots):
+    assert len(slots) == len(expected_slots)
+    for slot_id, (expected, slot) in enumerate(zip(expected_slots, slots)):
+        for key in expected:
+            assert expected[key] == slot[key], (f"invalid slot {slot_id}"
+                                                f" expected[{key}] != slot[{key}]"
+                                                f" = {expected[key]} != {slot[key]}")
+
+
+def start_server_background(context):
+    context.server_path = '../../../build/bin/server'
+    if 'LLAMA_SERVER_BIN_PATH' in os.environ:
+        context.server_path = os.environ['LLAMA_SERVER_BIN_PATH']
+    server_args = [
+        '--host', context.server_fqdn,
+        '--port', context.server_port,
+        '--model', context.model_file
+    ]
+    if context.server_continuous_batching:
+        server_args.append('--cont-batching')
+    if context.server_embeddings:
+        server_args.append('--embedding')
+    if context.model_alias is not None:
+        server_args.extend(['--alias', context.model_alias])
+    if context.n_ctx is not None:
+        server_args.extend(['--ctx-size', context.n_ctx])
+    if context.n_slots is not None:
+        server_args.extend(['--parallel', context.n_slots])
+    if context.n_server_predict is not None:
+        server_args.extend(['--n-predict', context.n_server_predict])
+    if context.server_api_key is not None:
+        server_args.extend(['--api-key', context.server_api_key])
+    if context.debug:
+        server_args.append('--verbose')
+    print(f"starting server with: {context.server_path}", *server_args)
+    context.server_process = subprocess.Popen(
+        [str(arg) for arg in [context.server_path, *server_args]],
+        close_fds=True)
+    print(f"server pid={context.server_process.pid}")
diff --git a/examples/server/tests/features/wrong_usages.feature b/examples/server/tests/features/wrong_usages.feature
new file mode 100644
index 00000000..e228b237
--- /dev/null
+++ b/examples/server/tests/features/wrong_usages.feature
@@ -0,0 +1,21 @@
+# run with ./test.sh --tags wrong_usage
+@wrong_usage
+Feature: Wrong usage of llama.cpp server
+
+  #3969 The user must always set --n-predict option
+  # to cap the number of tokens any completion request can generate
+  # or pass n_predict/max_tokens in the request.
+  Scenario: Infinite loop
+    Given a server listening on localhost:8080
+    And   a model file stories260K.gguf
+    # Uncomment below to fix the issue
+    #And   64 server max tokens to predict
+    Then  the server is starting
+    Given a prompt:
+      """
+      Go to: infinite loop
+      """
+    # Uncomment below to fix the issue
+    #And   128 max tokens to predict
+    Given concurrent completion requests
+    Then all prompts are predicted
diff --git a/examples/server/tests/requirements.txt b/examples/server/tests/requirements.txt
new file mode 100644
index 00000000..3e51b12d
--- /dev/null
+++ b/examples/server/tests/requirements.txt
@@ -0,0 +1,3 @@
+aiohttp~=3.9.3
+behave~=1.2.6
+openai~=0.25.0
diff --git a/examples/server/tests/tests.sh b/examples/server/tests/tests.sh
new file mode 100755
index 00000000..17a4e6fc
--- /dev/null
+++ b/examples/server/tests/tests.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -eu
+
+if [ $# -lt 1 ]
+then
+  # Start @llama.cpp scenario
+  behave --summary --stop --no-capture --exclude 'issues|wrong_usages' --tags llama.cpp
+else
+  behave "$@"
+fi
+