From 6dc8bdf828003b03571924ab4351c02ea0ba7add Mon Sep 17 00:00:00 2001
From: Greg Hellings <greg.hellings@gmail.com>
Date: Wed, 18 Sep 2024 12:51:07 -0500
Subject: [PATCH] feat: Add support for mongodb

MongoDB currently fails to build on Darwin because of a transitive build
dep on jaraco-path. So we make the test dependent on that. I do not,
however, choose to completely disable MongoDB because someone might have
workarounds for the package building in their environment.
---
 doc/mongodb.md                |  11 +++
 doc/services.md               |   1 +
 nix/services/default.nix      |   1 +
 nix/services/mongodb.nix      | 131 ++++++++++++++++++++++++++++++++++
 nix/services/mongodb_test.nix |  22 ++++++
 test/flake.nix                |   4 ++
 6 files changed, 170 insertions(+)
 create mode 100644 doc/mongodb.md
 create mode 100644 nix/services/mongodb.nix
 create mode 100644 nix/services/mongodb_test.nix

diff --git a/doc/mongodb.md b/doc/mongodb.md
new file mode 100644
index 00000000..0f286b76
--- /dev/null
+++ b/doc/mongodb.md
@@ -0,0 +1,11 @@
+# MongoDB
+
+[MongoDB](https://www.mongodb.com/) is a popular document database that is available. It comes in a variety of flavors, but the version packaged by NixPkgs is generally the community edition.
+
+Because of the licensing of MongoDB, the Nixpkgs derivation that provides the binaries of this database are generally not built and cached by the public nixpkgs cache. Because of this, the initial launch time can be very slow, the first time you use this service locally. On a laptop this time ran to about 3 hours for the initial compile. After the initial build, the start up should be very fast, as with other services, provided you do not update your flake.lock.
+
+If you are using this for your own development, you should either put in place a [local binary cache](https://nixos.wiki/wiki/Binary_Cache) to match your flake, or be aware that the first time you spin up the service it could possibly take a long time to build.
+
+## Usage example
+
+<https://github.com/juspay/services-flake/blob/main/nix/services/mongodb_test.nix>
diff --git a/doc/services.md b/doc/services.md
index c52ac0dc..6c8404e2 100644
--- a/doc/services.md
+++ b/doc/services.md
@@ -11,6 +11,7 @@ short-title: Services
 - [[grafana]]#
   - [[tempo]]
 - [[memcached]]#
+- [[mongodb]]#
 - [[mysql]]#
 - [[nginx]]#
 - [[ollama]]#
diff --git a/nix/services/default.nix b/nix/services/default.nix
index 5591c5e3..f3b9dc10 100644
--- a/nix/services/default.nix
+++ b/nix/services/default.nix
@@ -23,5 +23,6 @@ in
     ./weaviate.nix
     ./searxng.nix
     ./tika.nix
+    ./mongodb.nix
   ];
 }
diff --git a/nix/services/mongodb.nix b/nix/services/mongodb.nix
new file mode 100644
index 00000000..c7235b79
--- /dev/null
+++ b/nix/services/mongodb.nix
@@ -0,0 +1,131 @@
+{ pkgs, lib, name, config, ... }:
+let
+  inherit (lib) types;
+in
+{
+  options = {
+    package = lib.mkPackageOption pkgs "mongodb" { };
+
+    bind = lib.mkOption {
+      type = types.nullOr types.str;
+      default = "127.0.0.1";
+      description = ''
+        The IP interface to bind to.
+        `null` means "all interfaces".
+      '';
+      example = "127.0.0.1";
+    };
+
+    port = lib.mkOption {
+      type = types.port;
+      default = 27017;
+      description = ''
+        The TCP port to accept connections.
+      '';
+    };
+
+    user = lib.mkOption {
+      type = types.str;
+      default = "default";
+      description = ''
+        The name of the first user to create in
+        Mongo.
+      '';
+      example = "my_user";
+    };
+
+    password = lib.mkOption {
+      type = types.str;
+      default = "password";
+      description = ''
+        The password of the user to configure
+        for initial access.
+      '';
+    };
+
+    extraConfig = lib.mkOption {
+      type = types.lines;
+      default = "";
+      description = "Additional text to be appended to `mongodb.conf`.";
+    };
+  };
+
+  config = {
+    outputs = {
+      settings = {
+        processes = {
+          "${name}" =
+            let
+              mongoConfig = pkgs.writeText "mongodb.conf" ''
+                net.port: ${toString config.port}
+                net.bindIp: ${config.bind}
+                storage.dbPath: ${config.dataDir}
+                ${config.extraConfig}
+              '';
+
+              startScript = pkgs.writeShellApplication {
+                name = "start-mongodb";
+                runtimeInputs = [ pkgs.coreutils config.package ];
+                text = ''
+                  set -euo pipefail
+
+                  export MONGODATA="${config.dataDir}"
+
+                  if [[ ! -d "$MONGODATA" ]]; then
+                    mkdir -p "$MONGODATA"
+                  fi
+
+                  exec mongod --config "${mongoConfig}"
+                '';
+              };
+            in
+            {
+              command = startScript;
+
+              readiness_probe = {
+                exec.command = "${pkgs.mongosh}/bin/mongosh --eval \"db.version()\" > /dev/null 2>&1";
+                initial_delay_seconds = 2;
+                period_seconds = 10;
+                timeout_seconds = 4;
+                success_threshold = 1;
+                failure_threshold = 5;
+              };
+
+              # https://github.com/F1bonacc1/process-compose#-auto-restart-if-not-healthy
+              availability = {
+                restart = "on_failure";
+                max_restarts = 5;
+              };
+            };
+          "${name}-configure" =
+            let
+              configScript = pkgs.writeShellApplication {
+                name = "configure-mongo";
+                text = ''
+                  if ! test -e "${config.dataDir}/.auth_configured"; then
+                    ${config.package}/bin/mongo <<EOF
+                      use admin
+                      db.createUser({
+                        user: "${config.user}",
+                        pwd: "${config.password}",
+                        roles: [
+                          { role: "userAdminAnyDatabase", db: "admin" },
+                          { role: "dbAdminAnyDatabase", db: "admin" },
+                          { role: "readWriteAnyDatabase", db: "admin" }
+                        ]
+                      })
+                  EOF
+                    touch "${config.dataDir}/.auth_configured"
+                  fi
+                '';
+              };
+            in
+            {
+              command = configScript;
+              depends_on."${name}".condition = "process_healthy";
+            };
+        };
+      };
+    };
+  };
+}
diff --git a/nix/services/mongodb_test.nix b/nix/services/mongodb_test.nix
new file mode 100644
index 00000000..fec46744
--- /dev/null
+++ b/nix/services/mongodb_test.nix
@@ -0,0 +1,22 @@
+{ pkgs, config, ... }:
+{
+  services.mongodb."mongo1".enable = true;
+
+  settings.processes.test =
+    let
+      cfg = config.services.mongodb."mongo1";
+    in
+    {
+      command = pkgs.writeShellApplication {
+        runtimeInputs = [
+          cfg.package
+          pkgs.mongosh
+        ];
+        text = ''
+          mongosh --username default --password password mongodb://127.0.0.1/ --authenticationDatabase admin
+        '';
+        name = "mongo-test";
+      };
+      depends_on."mongo1-configure".condition = "process_completed_successfully";
+    };
+}
diff --git a/test/flake.nix b/test/flake.nix
index e4ff3327..9364a56d 100644
--- a/test/flake.nix
+++ b/test/flake.nix
@@ -51,6 +51,10 @@
             "${inputs.services-flake}/nix/services/tika_test.nix"
             "${inputs.services-flake}/nix/services/weaviate_test.nix"
             "${inputs.services-flake}/nix/services/zookeeper_test.nix"
+          ] ++ lib.optionals pkgs.stdenv.hostPlatform.isLinux [
+            # Due to a dependency problem, MongoDB does not build on Darwin,
+            # See https://github.com/NixOS/nixpkgs/issues/346003
+            "${inputs.services-flake}/nix/services/mongodb_test.nix"
           ]));
       };
     };