llama.cpp/tools/server/server.cpp

#include "server-context.h"
#include "server-http.h"
#include "server-models.h"
#include "server-cors-proxy.h"
#include "server-stream.h"
#include "server-tools.h"

#include "arg.h"
#include "build-info.h"
#include "common.h"
#include "fit.h"
#include "llama.h"
#include "log.h"

#include <atomic>
#include <clocale>
#include <exception>
#include <signal.h>
#include <thread> // for std::thread::hardware_concurrency

#if defined(_WIN32)
#include <windows.h>
#endif

static std::function<void(int)> shutdown_handler;
static std::atomic_flag is_terminating = ATOMIC_FLAG_INIT;

static inline void signal_handler(int signal) {
    if (is_terminating.test_and_set()) {
        // in case it hangs, we can force terminate the server by hitting Ctrl+C twice
        // this is for better developer experience, we can remove when the server is stable enough
        fprintf(stderr, "Received second interrupt, terminating immediately.\n");
        exit(1);
    }

    shutdown_handler(signal);
}

// satisfies -Wmissing-declarations (used by llama command)
int llama_server(int argc, char ** argv);

// to be used via CLI (argc / argv are used by router mode only)
int llama_server(common_params & params, int argc, char ** argv);
void llama_server_terminate();
void llama_server_terminate() {
    if (shutdown_handler) {
        shutdown_handler(0);
    }
}


// wrapper function that handles exceptions and logs errors
// this is to make sure handler_t never throws exceptions; instead, it returns an error response
static server_http_context::handler_t ex_wrapper(server_http_context::handler_t func) {
    return [func = std::move(func)](const server_http_req & req) -> server_http_res_ptr {
        std::string message;
        error_type error;
        try {
            return func(req);
        } catch (const std::invalid_argument & e) {
            // treat invalid_argument as invalid request (400)
            error = ERROR_TYPE_INVALID_REQUEST;
            message = e.what();
        } catch (const std::exception & e) {
            // treat other exceptions as server error (500)
            error = ERROR_TYPE_SERVER;
            message = e.what();
        } catch (...) {
            error = ERROR_TYPE_SERVER;
            message = "unknown error";
        }

        auto res = std::make_unique<server_http_res>();
        res->status = 500;
        try {
            json error_data = format_error_response(message, error);
            res->status = json_value(error_data, "code", 500);
            res->data = safe_json_to_str({{ "error", error_data }});
            SRV_WRN("got exception: %s\n", res->data.c_str());
        } catch (const std::exception & e) {
            SRV_ERR("got another exception: %s | while handling exception: %s\n", e.what(), message.c_str());
            res->data = "Internal Server Error";
        }
        return res;
    };
}

int llama_server(int argc, char ** argv) {
    std::setlocale(LC_NUMERIC, "C");

#ifndef _WIN32
    // Ignore SIGPIPE so the server does not crash if an MCP child exits while we are writing to its stdin
    signal(SIGPIPE, SIG_IGN);
#endif

    // own arguments required by this example
    common_params params;

    common_init();

    // start the stream session manager GC right after common init, before any HTTP route can
    // touch it. lifecycle is symmetric, stop_gc() runs in clean_up() before backend free
    server_stream_session_manager_start();

    if (!common_params_parse(argc, argv, params, LLAMA_EXAMPLE_SERVER)) {
        return 1;
    }

    llama_backend_init();
    llama_numa_init(params.numa);

    return llama_server(params, argc, argv);
}

int llama_server(common_params & params, int argc, char ** argv) {
    bool is_run_by_cli = (argv == nullptr);

    common_models_handler models_handler;

    // note: router mode also accepts -hf remote-preset, so we need to check that first
    if (!is_run_by_cli && !params.model.hf_repo.empty()) {
        try {
            models_handler = common_models_handler_init(params, LLAMA_EXAMPLE_SERVER);
            if (common_models_handler_is_preset_repo(models_handler)) {
                // apply the preset and start the server in router mode
                common_models_handler_apply(models_handler, params);
            }
        } catch (const std::exception & e) {
            SRV_ERR("failed to fetch model metadata: %s\n", e.what());
            return 1;
        }
    }

    // router server never loads a model and must not touch the GPU
    const bool is_router_server = params.model.path.empty()
                               && params.model.hf_repo.empty();

    // skip device enumeration so the CUDA primary context stays uncreated
    common_params_print_info(params, !is_router_server);

    if (!is_router_server) {
        // validate batch size for embeddings
        // embeddings require all tokens to be processed in a single ubatch
        // see https://github.com/ggml-org/llama.cpp/issues/12836
        if (params.embedding && params.n_batch > params.n_ubatch) {
            SRV_WRN("embeddings enabled with n_batch (%d) > n_ubatch (%d)\n", params.n_batch, params.n_ubatch);
            SRV_WRN("setting n_batch = n_ubatch = %d to avoid assertion failure\n", params.n_ubatch);
            params.n_batch = params.n_ubatch;
        }

        if (params.n_parallel < 0) {
            SRV_TRC("%s", "n_parallel is set to auto, using n_parallel = 4 and kv_unified = true\n");

            params.n_parallel = 4;
            params.kv_unified = true;
        }
    }

    // for consistency between server router mode and single-model mode, we set the same model name as alias
    auto model_name = params.model.get_name();
    if (params.model_alias.empty() && !model_name.empty()) {
        params.model_alias.insert(model_name);
    }

    // note: this is guaranteed to out-live ctx_http and tools
    server_mcp mcp_mgr;

    // struct that contains llama context and inference
    server_context ctx_server;

    server_http_context ctx_http;
    if (!ctx_http.init(params)) {
        SRV_ERR("%s", "failed to initialize HTTP server\n");
        return 1;
    }

    //
    // Router
    //

    // register API routes
    server_child child; // only used in non-router mode
    server_routes routes(params, ctx_server);
    server_tools tools;

    std::optional<server_models_routes> models_routes{};
    if (is_router_server) {
        // setup server instances manager
        try {
            models_routes.emplace(params, argc, argv);
        } catch (const std::exception & e) {
            SRV_ERR("failed to initialize router models: %s\n", e.what());
            return 1;
        }

        // proxy handlers
        // note: routes.get_health stays the same
        routes.get_metrics                 = models_routes->proxy_get;
        routes.post_props                  = models_routes->proxy_post;
        routes.post_completions            = models_routes->proxy_post;
        routes.post_completions_oai        = models_routes->proxy_post;
        routes.post_chat_completions       = models_routes->proxy_post;
        routes.post_control                = models_routes->proxy_post;
        routes.post_responses_oai          = models_routes->proxy_post;
        routes.post_transcriptions_oai     = models_routes->proxy_post;
        routes.post_anthropic_messages     = models_routes->proxy_post;
        routes.post_anthropic_count_tokens = models_routes->proxy_post;
        routes.post_infill                 = models_routes->proxy_post;
        routes.post_embeddings             = models_routes->proxy_post;
        routes.post_embeddings_oai         = models_routes->proxy_post;
        routes.post_rerank                 = models_routes->proxy_post;
        routes.post_tokenize               = models_routes->proxy_post;
        routes.post_detokenize             = models_routes->proxy_post;
        routes.post_apply_template         = models_routes->proxy_post;
        routes.post_chat_completions_tok   = models_routes->proxy_post;
        routes.post_responses_tok_oai      = models_routes->proxy_post;
        routes.get_lora_adapters           = models_routes->proxy_get;
        routes.post_lora_adapters          = models_routes->proxy_post;
        routes.get_slots                   = models_routes->proxy_get;
        routes.post_slots                  = models_routes->proxy_post;

        // custom routes for router
        routes.get_props                   = models_routes->get_router_props;
        routes.get_models                  = models_routes->get_router_models;

        ctx_http.post("/models",               ex_wrapper(models_routes->post_router_models));
        ctx_http.post("/models/load",          ex_wrapper(models_routes->post_router_models_load));
        ctx_http.post("/models/unload",        ex_wrapper(models_routes->post_router_models_unload));
        ctx_http.get ("/models/sse",           ex_wrapper(models_routes->get_router_models_sse));
        ctx_http.del ("/models",               ex_wrapper(models_routes->del_router_models));
    }

    ctx_http.get ("/health",                   ex_wrapper(routes.get_health)); // public endpoint (no API key check)
    ctx_http.get ("/v1/health",                ex_wrapper(routes.get_health)); // public endpoint (no API key check)
    ctx_http.get ("/metrics",                  ex_wrapper(routes.get_metrics));
    ctx_http.get ("/props",                    ex_wrapper(routes.get_props));
    ctx_http.post("/props",                    ex_wrapper(routes.post_props));
    ctx_http.get ("/models",                   ex_wrapper(routes.get_models)); // public endpoint (no API key check)
    ctx_http.get ("/v1/models",                ex_wrapper(routes.get_models)); // public endpoint (no API key check)
    ctx_http.post("/completion",               ex_wrapper(routes.post_completions)); // legacy
    ctx_http.post("/completions",              ex_wrapper(routes.post_completions));
    ctx_http.post("/v1/completions",           ex_wrapper(routes.post_completions_oai));
    ctx_http.post("/chat/completions",         ex_wrapper(routes.post_chat_completions));
    ctx_http.post("/v1/chat/completions",      ex_wrapper(routes.post_chat_completions));
    ctx_http.post("/v1/chat/completions/control", ex_wrapper(routes.post_control));
    ctx_http.post("/v1/responses",             ex_wrapper(routes.post_responses_oai));
    ctx_http.post("/responses",                ex_wrapper(routes.post_responses_oai));
    ctx_http.post("/v1/audio/transcriptions",  ex_wrapper(routes.post_transcriptions_oai));
    ctx_http.post("/audio/transcriptions",     ex_wrapper(routes.post_transcriptions_oai));
    ctx_http.post("/v1/messages",              ex_wrapper(routes.post_anthropic_messages)); // anthropic messages API
    ctx_http.post("/infill",                   ex_wrapper(routes.post_infill));
    ctx_http.post("/embedding",                ex_wrapper(routes.post_embeddings)); // legacy
    ctx_http.post("/embeddings",               ex_wrapper(routes.post_embeddings));
    ctx_http.post("/v1/embeddings",            ex_wrapper(routes.post_embeddings_oai));
    ctx_http.post("/rerank",                   ex_wrapper(routes.post_rerank));
    ctx_http.post("/reranking",                ex_wrapper(routes.post_rerank));
    ctx_http.post("/v1/rerank",                ex_wrapper(routes.post_rerank));
    ctx_http.post("/v1/reranking",             ex_wrapper(routes.post_rerank));
    ctx_http.post("/tokenize",                 ex_wrapper(routes.post_tokenize));
    ctx_http.post("/detokenize",               ex_wrapper(routes.post_detokenize));
    ctx_http.post("/apply-template",           ex_wrapper(routes.post_apply_template));
    // token counting
    ctx_http.post("/chat/completions/input_tokens",    ex_wrapper(routes.post_chat_completions_tok));
    ctx_http.post("/v1/chat/completions/input_tokens", ex_wrapper(routes.post_chat_completions_tok));
    ctx_http.post("/responses/input_tokens",           ex_wrapper(routes.post_responses_tok_oai));
    ctx_http.post("/v1/responses/input_tokens",        ex_wrapper(routes.post_responses_tok_oai));
    ctx_http.post("/v1/messages/count_tokens",         ex_wrapper(routes.post_anthropic_count_tokens)); // anthropic token counting
    // LoRA adapters hotswap
    ctx_http.get ("/lora-adapters",            ex_wrapper(routes.get_lora_adapters));
    ctx_http.post("/lora-adapters",            ex_wrapper(routes.post_lora_adapters));
    // Save & load slots
    ctx_http.get ("/slots",                    ex_wrapper(routes.get_slots));
    ctx_http.post("/slots/:id_slot",           ex_wrapper(routes.post_slots));

    // resumable streaming, the conversation_id is the session identity end to end. router and
    // child wire different handlers under the same paths: a child binds the local session
    // factories, the router binds proxies that resolve the owning child through the
    // conv_id -> model map
    server_http_context::handler_t stream_get_h;
    server_http_context::handler_t streams_lookup_h;
    server_http_context::handler_t stream_delete_h;
    if (is_router_server) {
        stream_get_h     = models_routes->router_stream_get;
        streams_lookup_h = models_routes->router_streams_lookup;
        stream_delete_h  = models_routes->router_stream_delete;
    } else {
        stream_get_h     = server_stream_make_get_handler();
        streams_lookup_h = server_stream_make_lookup_handler();
        stream_delete_h  = server_stream_make_delete_handler();
    }
    ctx_http.get ("/v1/stream/:conv_id",       ex_wrapper(stream_get_h));
    // POST /v1/streams/lookup with body {"conversation_ids": [...]}. you can only ask for ids
    // you already own (the WebUI passes the convs visible in its sidebar). the server never
    // lists ids it has not been asked about, so a random caller cannot enumerate live sessions
    ctx_http.post("/v1/streams/lookup",        ex_wrapper(streams_lookup_h));
    ctx_http.del ("/v1/stream/:conv_id",       ex_wrapper(stream_delete_h));

    // Google Cloud Platform (Vertex AI) compat
    ctx_http.register_gcp_compat();

    // return 403 for disabled features
    server_http_context::handler_t res_403 = [](const server_http_req &) {
        auto res = std::make_unique<server_http_res>();
        res->status = 403;
        res->data = safe_json_to_str({
            {"error", {
                {"message", "this feature is disabled"},
                {"type", "feature_disabled"},
            }}
        });
        return res;
    };

    if (params.cors_origins == "*" && params.api_keys.empty()) {
        SRV_WRN("%s", "-----------------\n");
        SRV_WRN("%s", "CORS is set to allow all origins ('*') and no API key is set\n");
        SRV_WRN("%s", "this can be a security risk (cross-origin attacks)\n");
        SRV_WRN("%s", "more info: https://github.com/ggml-org/llama.cpp/pull/25655\n");
        SRV_WRN("%s", "-----------------\n");
    }

    // CORS proxy (EXPERIMENTAL, only used by the Web UI for MCP)
    std::vector<std::string> warn_names;
    if (is_router_server) {
        warn_names.push_back("router mode");
    }

    if (params.ui_mcp_proxy) {
        ctx_http.get ("/cors-proxy",      ex_wrapper(proxy_handler_get));
        ctx_http.post("/cors-proxy",      ex_wrapper(proxy_handler_post));
        warn_names.push_back("MCP proxy (experimental)");
    } else {
        ctx_http.get ("/cors-proxy",      ex_wrapper(res_403));
        ctx_http.post("/cors-proxy",      ex_wrapper(res_403));
    }

    try {
        mcp_mgr.start(params);
    } catch (const std::exception & e) {
        SRV_ERR("MCP starting failed: %s\n", e.what());
        return 1;
    }

    if (!params.server_tools.empty() || !mcp_mgr.empty()) {
        try {
            tools.setup(params.server_tools, mcp_mgr);
        } catch (const std::exception & e) {
            SRV_ERR("tools setup failed: %s\n", e.what());
            return 1;
        }
        ctx_http.get ("/tools",           ex_wrapper(tools.handle_get));
        ctx_http.post("/tools",           ex_wrapper(tools.handle_post));
        if (!params.server_tools.empty()) {
            warn_names.push_back("built-in tools (experimental)");
        }
        if (!mcp_mgr.empty()) {
            warn_names.push_back("MCP servers (experimental)");
        }
    } else {
        ctx_http.get ("/tools",           ex_wrapper(res_403));
        ctx_http.post("/tools",           ex_wrapper(res_403));
    }

    if (warn_names.size() > 0) {
        SRV_WRN("%s", "-----------------\n");
        SRV_WRN("%s", "the following feature(s) are enabled:\n");
        for (const auto & name : warn_names) {
            SRV_WRN("    %s\n", name.c_str());
        }
        SRV_WRN("%s", "do not expose the server to untrusted environments\n");
        SRV_WRN("%s", "-----------------\n");
    }

    //
    // Handle downloading model
    //

    if (child.is_child() && child.get_mode() == SERVER_CHILD_MODE_DOWNLOAD) {
        return child.run_download(params);
    } else if (!is_router_server && !is_run_by_cli) {
        // single-model mode (NOT spawned by router)
        // if this is invoked by CLI, model downloading should be already handled
        try {
            common_models_handler_apply(models_handler, params);
        } catch (const std::exception & e) {
            SRV_ERR("failed to download model: %s\n", e.what());
            return 1;
        }
    }

    //
    // Start the server
    //

    std::function<void()> clean_up;

    if (is_router_server) {
        SRV_INF("%s", "starting server in router mode. models will be automatically loaded on-demand\n");

        clean_up = [&models_routes, &mcp_mgr]() {
            SRV_INF("%s: cleaning up before exit...\n", __func__);
            // stop the session GC first, it finalizes live sessions and wakes pending readers
            server_stream_session_manager_stop();
            if (models_routes.has_value()) {
                models_routes->stopping.store(true); // maybe redundant, but just to be safe
                models_routes->models.unload_all();
            }
            mcp_mgr.shutdown();
            llama_backend_free();
        };

        if (!ctx_http.start()) {
            clean_up();
            SRV_ERR("%s", "exiting due to HTTP server error\n");
            return 1;
        }
        ctx_http.is_ready.store(true);

        shutdown_handler = [&](int) {
            if (models_routes.has_value()) {
                // important to disconnect any SSE clients
                models_routes->stopping.store(true);
            }
            mcp_mgr.shutdown();
            ctx_http.stop();
        };

    } else {
        // setup clean up function, to be called before exit
        clean_up = [&ctx_http, &ctx_server, &mcp_mgr]() {
            SRV_INF("%s: cleaning up before exit...\n", __func__);
            // stop the session GC first, it finalizes live sessions and wakes pending readers
            server_stream_session_manager_stop();
            ctx_http.stop();
            ctx_server.terminate();
            mcp_mgr.shutdown();
            llama_backend_free();
        };

        // start the HTTP server before loading the model to be able to serve /health requests
        if (!ctx_http.start()) {
            clean_up();
            SRV_ERR("%s", "exiting due to HTTP server error\n");
            return 1;
        }

        // setup communication child --> router if necessary
        if (child.is_child()) {
            ctx_server.set_state_callback([&](server_state state, json payload) {
                child.notify_to_router(server_state_to_str(state), payload);
            });
        }

        if (!ctx_server.load_model(params)) {
            clean_up();
            if (ctx_http.thread.joinable()) {
                ctx_http.thread.join();
            }
            SRV_ERR("%s", "exiting due to model loading error\n");
            return 1;
        }

        routes.update_meta(ctx_server);
        ctx_http.is_ready.store(true);

        SRV_INF("%s", "model loaded\n");

        shutdown_handler = [&](int) {
            mcp_mgr.shutdown();
            // this will unblock start_loop()
            ctx_server.terminate();
        };
    }

    // register signal handler if not running by CLI
    if (!is_run_by_cli) {
#if defined (__unix__) || (defined (__APPLE__) && defined (__MACH__))
        struct sigaction sigint_action;
        sigint_action.sa_handler = signal_handler;
        sigemptyset (&sigint_action.sa_mask);
        sigint_action.sa_flags = 0;
        sigaction(SIGINT, &sigint_action, NULL);
        sigaction(SIGTERM, &sigint_action, NULL);
#elif defined (_WIN32)
        auto console_ctrl_handler = +[](DWORD ctrl_type) -> BOOL {
            return (ctrl_type == CTRL_C_EVENT) ? (signal_handler(SIGINT), true) : false;
        };
        SetConsoleCtrlHandler(reinterpret_cast<PHANDLER_ROUTINE>(console_ctrl_handler), true);
#endif
    }

    SRV_INF("listening on %s\n", ctx_http.listening_address.c_str());

    if (is_router_server) {
        if (!params.models_preset_hf.empty()) {
            SRV_WRN(      "NOTE: using preset.ini from HF repo '%s'\n", params.models_preset_hf.c_str());
            SRV_WRN("%s", "      please only use presets that you can trust! Unknown presets may be unsafe\n");
        }

        if (ctx_http.thread.joinable()) {
            ctx_http.thread.join(); // keep the main thread alive
        }

        // when the HTTP server stops, clean up and exit
        clean_up();
    } else {
        // optionally, notify router server that this instance is ready
        std::thread monitor_thread;
        if (child.is_child()) {
            monitor_thread = child.setup(shutdown_handler);
            child.notify_to_router(server_state_to_str(SERVER_STATE_READY), routes.get_model_info());
        }

        // this call blocks the main thread until queue_tasks.terminate() is called
        ctx_server.start_loop();

        clean_up();
        if (ctx_http.thread.joinable()) {
            ctx_http.thread.join();
        }
        if (monitor_thread.joinable()) {
            monitor_thread.join();
        }

        auto * ll_ctx = ctx_server.get_llama_context();
        if (ll_ctx != nullptr) {
            common_memory_breakdown_print(ll_ctx);
        }
    }

    return 0;
}