feat(open-webui): init

ported from:
https://github.com/shivaraj-bh/ollama-flake/blob/main/services/open-webui.nix

This was also recently upstreamed to
[nixpkgs](https://github.com/NixOS/nixpkgs/tree/master):
https://github.com/NixOS/nixpkgs/pull/316248

---------

Co-authored-by: Pol Dellaiera <pol.dellaiera@protonmail.com>
Co-authored-by: Sridhar Ratnakumar <3998+srid@users.noreply.github.com>

doc/open-webui.md

@@ -0,0 +1,68 @@
+# Open WebUI
+
+[Open WebUI](https://github.com/open-webui/open-webui) is a user-friendly WebUI for LLMs. It supports various LLM runners, including [[ollama]] and OpenAI-compatible APIs.
+
+{#start}
+## Getting Started
+
+```nix
+# In `perSystem.process-compose.<name>`
+{
+  services.open-webui."open-webui1".enable = true;
+}
+```
+
+## Examples
+
+{#ollama}
+### Open WebUI with ollama backend
+
+```nix
+{
+  services = {
+    # Backend service to perform inference on LLM models
+    ollama."ollama1" = {
+      enable = true;
+      # The models are usually huge, downloading them in every project directory can lead to a lot of duplication
+      dataDir = "$HOME/.services-flake/ollama1";
+      models = [ "llama2-uncensored" ];
+    };
+    # Get ChatGPT like UI, but open-source, with Open WebUI
+    open-webui."open-webui1" = {
+      enable = true;
+      environment =
+        let
+          inherit (pc.config.services.ollama.ollama1) host port;
+        in
+        {
+          OLLAMA_API_BASE_URL = "http://${host}:${toString port}";
+          WEBUI_AUTH = "False";
+        };
+    };
+  };
+  # Start the Open WebUI service after the Ollama service has finished initializing and loading the models
+  settings.processes.open-webui1.depends_on.ollama1-models.condition = "process_completed_successfully";
+}
+```
+
+See [[ollama]] for more customisation of the backend.
+
+{#browser}
+## Open browser on startup
+
+```nix
+{
+  services.open-webui."open-webui1".enable = true;
+  # Open the browser after the Open WebUI service has started
+  settings.processes.open-browser = {
+    command =
+      let
+        inherit (pc.config.services.open-webui.open-webui1) host port;
+        opener = if pkgs.stdenv.isDarwin then "open" else lib.getExe' pkgs.xdg-utils "xdg-open";
+        url = "http://${host}:${toString port}";
+      in
+      "${opener} ${url}";
+    depends_on.open-webui1.condition = "process_healthy";
+  };
+}
+```

doc/services.md

@@ -13,6 +13,7 @@ short-title: Services
 - [[mysql]]#
 - [[nginx]]#
 - [[ollama]]#
+- [[open-webui]]#
 - [[postgresql]]#
   - [[pgadmin]]
 - [[redis]]#

example/llm/flake.nix

@@ -13,14 +13,46 @@
       inputs.process-compose-flake.flakeModule
     ];
     perSystem = { self', pkgs, lib, ... }: {
-      process-compose."default" = {
+      process-compose."default" = pc: {
         imports = [
           inputs.services-flake.processComposeModules.default
         ];
-        services.ollama."ollama1" = {
+        services = {
+          # Backend service to perform inference on LLM models
+          ollama."ollama1" = {
             enable = true;
+            # The models are usually huge, downloading them in every project directory can lead to a lot of duplication
+            dataDir = "$HOME/.services-flake/ollama1";
             models = [ "llama2-uncensored" ];
           };
+          # Get ChatGPT like UI, but open-source, with Open WebUI
+          open-webui."open-webui1" = {
+            enable = true;
+            environment =
+              let
+                inherit (pc.config.services.ollama.ollama1) host port;
+              in
+              {
+                OLLAMA_API_BASE_URL = "http://${host}:${toString port}";
+                WEBUI_AUTH = "False";
+              };
+          };
+        };
+
+        # Start the Open WebUI service after the Ollama service has finished initializing and loading the models
+        settings.processes.open-webui1.depends_on.ollama1-models.condition = "process_completed_successfully";
+
+        # Open the browser after the Open WebUI service has started
+        settings.processes.open-browser = {
+          command =
+            let
+              inherit (pc.config.services.open-webui.open-webui1) host port;
+              opener = if pkgs.stdenv.isDarwin then "open" else lib.getExe' pkgs.xdg-utils "xdg-open";
+              url = "http://${host}:${toString port}";
+            in
+            "${opener} ${url}";
+          depends_on.open-webui1.condition = "process_healthy";
+        };
       };
     };
   };

nix/default.nix

@@ -11,6 +11,7 @@ in
     ./nginx
     ./ollama.nix
     ./postgres
+    ./open-webui.nix
     ./redis-cluster.nix
     ./redis.nix
     ./zookeeper.nix

nix/open-webui.nix

@@ -0,0 +1,107 @@
+# Based on: https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/services/misc/open-webui.nix
+{ pkgs, lib, name, config, ... }:
+let
+  inherit (lib) types;
+in
+{
+  options = {
+    enable = lib.mkEnableOption "Open-WebUI server";
+    package = lib.mkPackageOption pkgs "open-webui" { };
+
+    dataDir = lib.mkOption {
+      type = types.str;
+      default = "./data/${name}";
+      description = "The Open-WebUI data directory";
+    };
+
+    host = lib.mkOption {
+      type = types.str;
+      default = "127.0.0.1";
+      example = "0.0.0.0";
+      description = ''
+        The host address which the Open-WebUI server HTTP interface listens to.
+      '';
+    };
+
+    port = lib.mkOption {
+      type = types.port;
+      default = 1111;
+      example = 11111;
+      description = ''
+        Which port the Open-WebUI server listens to.
+      '';
+    };
+
+    environment = lib.mkOption {
+      type = types.attrsOf types.str;
+      default = {
+        SCARF_NO_ANALYTICS = "True";
+        DO_NOT_TRACK = "True";
+        ANONYMIZED_TELEMETRY = "False";
+      };
+      example = ''
+        {
+          OLLAMA_API_BASE_URL = "http://127.0.0.1:11434";
+          # Disable authentication
+          WEBUI_AUTH = "False";
+        }
+      '';
+      description = "Extra environment variables for Open-WebUI";
+    };
+
+    outputs.settings = lib.mkOption {
+      type = types.deferredModule;
+      internal = true;
+      readOnly = true;
+      default = {
+        processes = {
+          "${name}" =
+            let
+              setupStateDirs = lib.concatMapStrings
+                (stateDir:
+                  ''
+                    if [ ! -d "''$${stateDir}" ]; then
+                      mkdir -p "''$${stateDir}"
+                    fi
+
+                    ${stateDir}=$(readlink -f "''$${stateDir}")
+
+                    export ${stateDir}
+                  '') [ "DATA_DIR" "STATIC_DIR" "HF_HOME" "SENTENCE_TRANSFORMERS_HOME" ];
+            in
+
+            {
+              environment = {
+                DATA_DIR = config.dataDir;
+                STATIC_DIR = config.dataDir;
+                HF_HOME = config.dataDir;
+                SENTENCE_TRANSFORMERS_HOME = config.dataDir;
+              } // config.environment;
+
+              command = pkgs.writeShellApplication {
+                name = "open-webui-wrapper";
+                text = ''
+                  ${setupStateDirs}
+
+                  ${lib.getExe config.package} serve --host ${config.host} --port ${builtins.toString config.port}
+                '';
+              };
+              readiness_probe = {
+                http_get = {
+                  host = config.host;
+                  port = config.port;
+                };
+                initial_delay_seconds = 2;
+                period_seconds = 10;
+                timeout_seconds = 4;
+                success_threshold = 1;
+                failure_threshold = 5;
+              };
+              namespace = name;
+              availability.restart = "on_failure";
+            };
+        };
+      };
+    };
+  };
+}

nix/open-webui_test.nix

@@ -0,0 +1,21 @@
+{ pkgs, ... }: {
+  services.open-webui."open-webui1" = {
+    enable = true;
+    environment = {
+      # Requires network connection
+      RAG_EMBEDDING_MODEL = "";
+    };
+  };
+
+  settings.processes.test = {
+    command = pkgs.writeShellApplication {
+      runtimeInputs = [ pkgs.curl ];
+      text = ''
+        # Avoid printing the entire HTML page on the stdout, we just want to know if the page is active.
+        curl http://127.0.0.1:1111 > /dev/null
+      '';
+      name = "open-webui-test";
+    };
+    depends_on."open-webui1".condition = "process_healthy";
+  };
+}

test/flake.nix

@@ -39,6 +39,7 @@
             "${inputs.services-flake}/nix/mysql/mysql_test.nix"
             "${inputs.services-flake}/nix/nginx/nginx_test.nix"
             "${inputs.services-flake}/nix/ollama_test.nix"
+            "${inputs.services-flake}/nix/open-webui_test.nix"
             "${inputs.services-flake}/nix/postgres/postgres_test.nix"
             "${inputs.services-flake}/nix/redis_test.nix"
             "${inputs.services-flake}/nix/redis-cluster_test.nix"