Add redis service (#8)

README.md

@@ -17,7 +17,7 @@ TODO
 - [x] Hello World
 - [x] PostgreSQL
 - [ ] MySQL
-- [ ] Redis
+- [x] Redis
 - [ ] ...
 
 ## Contributing

nix/default.nix

@@ -2,5 +2,6 @@
   imports = [
     ./hello.nix
     ./postgres.nix
+    ./redis.nix
   ];
 }

nix/redis.nix

@@ -0,0 +1,98 @@
+# Based on https://github.com/cachix/devenv/blob/main/src/modules/services/redis.nix
+{ pkgs, lib, config, ... }:
+
+with lib;
+
+{
+  options.services.redis = lib.mkOption {
+    description = ''
+      Enable redis server
+    '';
+    default = { };
+    type = lib.types.submodule ({ config, ... }: {
+      options = {
+        enable = lib.mkEnableOption "redis";
+
+        name = lib.mkOption {
+          type = lib.types.str;
+          default = "redis";
+          description = "Unique process name";
+        };
+
+        package = lib.mkPackageOption pkgs "redis" { };
+
+        dataDir = lib.mkOption {
+          type = lib.types.str;
+          default = "./data/${config.name}";
+          description = "The redis data directory";
+        };
+
+        bind = mkOption {
+          type = types.nullOr types.str;
+          default = "127.0.0.1";
+          description = ''
+            The IP interface to bind to.
+            `null` means "all interfaces".
+          '';
+          example = "127.0.0.1";
+        };
+
+        port = mkOption {
+          type = types.port;
+          default = 6379;
+          description = ''
+            The TCP port to accept connections.
+
+            If port is set to `0`, redis will not listen on a TCP socket.
+          '';
+        };
+
+        extraConfig = mkOption {
+          type = types.lines;
+          default = "";
+          description = "Additional text to be appended to `redis.conf`.";
+        };
+      };
+    });
+
+  };
+
+  config = let cfg = config.services.redis; in lib.mkIf cfg.enable {
+
+    settings.processes.${cfg.name} =
+      let
+        redisConfig = pkgs.writeText "redis.conf" ''
+          port ${toString cfg.port}
+          ${optionalString (cfg.bind != null) "bind ${cfg.bind}"}
+          ${cfg.extraConfig}
+        '';
+
+        startScript = pkgs.writeShellScriptBin "start-redis" ''
+          set -euo pipefail
+
+          export REDISDATA=${cfg.dataDir}
+
+          if [[ ! -d "$REDISDATA" ]]; then
+            mkdir -p "$REDISDATA"
+          fi
+
+          exec ${cfg.package}/bin/redis-server ${redisConfig} --dir "$REDISDATA"
+        '';
+      in
+      {
+        command = "${startScript}/bin/start-redis";
+
+        readiness_probe = {
+          exec.command = "${cfg.package}/bin/redis-cli -p ${toString cfg.port} ping";
+          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";
+      };
+  };
+}

nix/redis_test.nix

@@ -0,0 +1,10 @@
+{ config, ... }: {
+  services.redis.enable = true;
+  testScript = ''
+    process_compose.wait_until(lambda procs:
+      # TODO: Check for 'is_ready' instead of 'status'
+      procs["redis"]["status"] == "Running"
+    )
+    machine.succeed("${config.services.redis.package}/bin/redis-cli ping | grep -q 'PONG'")
+  '';
+}

test/flake.nix

@@ -20,6 +20,12 @@
               ../nix/postgres_test.nix
             ];
           };
+          redis = {
+            imports = [
+              inputs.services-flake.processComposeModules.default
+              ../nix/redis_test.nix
+            ];
+          };
         };
       };
     };