Add Redis cluster service (#35)

README.md

@@ -19,6 +19,7 @@ TODO
 - [x] PostgreSQL
 - [ ] MySQL
 - [x] Redis
+- [x] Redis Cluster
 - [ ] ...
 
 ## A note on process working directory

nix/default.nix

@@ -36,5 +36,6 @@ in
   imports = builtins.map multiService [
     ./postgres.nix
     ./redis.nix
+    ./redis-cluster.nix
   ];
 }

nix/postgres.nix

@@ -343,7 +343,7 @@ in
 
                 initdbArgs =
                   config.initdbArgs
-                  ++ (lib.optionals (config.superuser != null) ["-U" config.superuser]);
+                  ++ (lib.optionals (config.superuser != null) [ "-U" config.superuser ]);
 
                 setupScript = pkgs.writeShellScriptBin "setup-postgres" ''
                   set -euo pipefail

nix/redis-cluster.nix

@@ -0,0 +1,133 @@
+{ pkgs, lib, name, config, ... }:
+let
+  inherit (lib) types;
+in
+{
+  options = {
+    enable = lib.mkEnableOption name;
+
+    package = lib.mkPackageOption pkgs "redis" { };
+
+    dataDir = lib.mkOption {
+      type = types.str;
+      default = "./data/${name}";
+      description = "The redis-cluster data directory (common for all nodes).";
+    };
+
+    nodes = lib.mkOption {
+      type = types.attrsOf (types.submodule {
+        options = {
+          port = lib.mkOption {
+            type = types.int;
+            description = "The TCP port to accept connections. If port is set to `0`, redis will not listen on a TCP socket.";
+          };
+          extraConfig = lib.mkOption {
+            type = types.lines;
+            description = "Extra configuration for this node. To be appended to `redis.conf`.";
+            default = "";
+          };
+        };
+      });
+      default = {
+        "n1" = { port = 30001; };
+        "n2" = { port = 30002; };
+        "n3" = { port = 30003; };
+        "n4" = { port = 30004; };
+        "n5" = { port = 30005; };
+        "n6" = { port = 30006; };
+      };
+    };
+
+    bind = lib.mkOption {
+      type = types.nullOr types.str;
+      default = "127.0.0.1";
+      description = ''
+        The IP interface to bind to.
+        `null` means "all interfaces".
+
+        All the nodes will follow the same bind address.
+      '';
+      example = "127.0.0.1";
+    };
+
+    timeout = lib.mkOption {
+      type = types.int;
+      default = 2000;
+      description = ''
+        Time (in milliseconds) after which the node is considered to be down.
+
+        If master node is down, a replica node will take over.
+      '';
+    };
+
+    replicas = lib.mkOption {
+      type = types.int;
+      default = 1;
+      description = ''
+        Number of replicas per Master node.
+      '';
+    };
+
+    outputs.settings = lib.mkOption {
+      type = types.deferredModule;
+      internal = true;
+      readOnly = true;
+      default =
+        let
+          mkNodeProcess = nodeName: cfg:
+            let
+              port = builtins.toString cfg.port;
+              redisConfig = pkgs.writeText "redis.conf" ''
+                port ${port}
+                cluster-enabled yes
+                cluster-config-file nodes-${port}.conf
+                cluster-node-timeout ${builtins.toString config.timeout}
+                appendonly yes
+                appendfilename "appendonly-${port}.aof"
+                dbfilename "dump-${port}.rdb"
+
+                ${lib.optionalString (config.bind != null) "bind ${config.bind}"}
+                ${cfg.extraConfig}
+              '';
+
+              startScript = pkgs.writeShellScriptBin "start-redis" ''
+                set -euo pipefail
+
+                export REDISDATA=${config.dataDir}
+
+                if [[ ! -d "$REDISDATA" ]]; then
+                  mkdir -p "$REDISDATA"
+                fi
+
+                exec ${config.package}/bin/redis-server ${redisConfig} --dir "$REDISDATA"
+              '';
+            in
+            lib.nameValuePair "${name}-${nodeName}" {
+              command = "${startScript}/bin/start-redis";
+              shutdown.command = "${config.package}/bin/redis-cli -p ${port} shutdown nosave";
+
+              readiness_probe = {
+                exec.command = "${config.package}/bin/redis-cli -p ${port} ping";
+                initial_delay_seconds = 2;
+                period_seconds = 10;
+                timeout_seconds = 4;
+                success_threshold = 1;
+                failure_threshold = 5;
+              };
+
+              # https://github.com/F1bonacc1/process-compose#-auto-restart-if-not-healthy
+              availability.restart = "on_failure";
+            };
+          hosts = lib.mapAttrsToList (_: cfg: "${config.bind}:${builtins.toString cfg.port}") config.nodes;
+        in
+        {
+          processes = (lib.mapAttrs' mkNodeProcess config.nodes) // {
+            "${name}-cluster-create" = {
+              depends_on = lib.mapAttrs' (nodeName: cfg: lib.nameValuePair "${name}-${nodeName}" { condition = "process_healthy"; }) config.nodes;
+              command = "${config.package}/bin/redis-cli --cluster create ${lib.concatStringsSep " " hosts} --cluster-replicas ${builtins.toString config.replicas} --cluster-yes";
+            };
+          };
+        };
+    };
+  };
+}

nix/redis-cluster_test.nix

@@ -0,0 +1,16 @@
+{ config, ... }: {
+  services.redis-cluster."c1".enable = true;
+  testScript = ''
+    process_compose.wait_until(lambda procs:
+      # TODO: Check for 'is_ready' of `c1-cluster-create` instead of `c1-n1` (status of `c1-cluster-create` determines whether the hashslots are assigned). 
+      #       This should be easy after https://github.com/juspay/services-flake/issues/32
+      procs["c1-n1"]["status"] == "Running"
+    )
+    machine.succeed("${config.services.redis-cluster.c1.package}/bin/redis-cli -p 30001 ping | grep -q 'PONG'")
+    machine.succeed("${config.services.redis-cluster.c1.package}/bin/redis-cli -p 30002 ping | grep -q 'PONG'")
+    machine.succeed("${config.services.redis-cluster.c1.package}/bin/redis-cli -p 30003 ping | grep -q 'PONG'")
+    machine.succeed("${config.services.redis-cluster.c1.package}/bin/redis-cli -p 30004 ping | grep -q 'PONG'")
+    machine.succeed("${config.services.redis-cluster.c1.package}/bin/redis-cli -p 30005 ping | grep -q 'PONG'")
+    machine.succeed("${config.services.redis-cluster.c1.package}/bin/redis-cli -p 30006 ping | grep -q 'PONG'")
+  '';
+}

test/flake.nix

@@ -26,6 +26,12 @@
               ../nix/redis_test.nix
             ];
           };
+          redis-cluster = {
+            imports = [
+              inputs.services-flake.processComposeModules.default
+              ../nix/redis-cluster_test.nix
+            ];
+          };
         };
       };
     };