Read redis hostname from REDIS_HOST env variable

Author: finestructure

Sources/App/Core/Dependencies/EnvironmentClient.swift

@@ -51,6 +51,7 @@ struct EnvironmentClient {
         case repositorySaveFailed
         case repositorySaveUniqueViolation
     }
+    var redisHostname: @Sendable () -> String = { "redis" }
     var shouldFail: @Sendable (_ failureMode: FailureMode) -> Bool = { _ in false }
 }
 
@@ -107,6 +108,12 @@ extension EnvironmentClient: DependencyKey {
                     .map(Mastodon.Credentials.init(accessToken:))
             },
             random: { range in Double.random(in: range) },
+            redisHostname: {
+                // Defaulting this to `redis`, which is the service name in `app.yml`.
+                // This is also why `REDIS_HOST` is not set as an env variable in `app.yml`,
+                // it's a known value that needs no configuration outside of local use for testing.
+                Environment.get("REDIS_HOST") ?? "redis"
+            },
             shouldFail: { failureMode in
                 let shouldFail = Environment.get("FAILURE_MODE")
                     .map { Data($0.utf8) }

Sources/App/Core/Dependencies/RedisClient.swift

@@ -109,15 +109,14 @@ private actor Redis {
     }
 
     private init() async throws {
+        @Dependency(\.environment) var environment
         let connection = RedisConnection.make(
-            configuration: try .init(hostname: Redis.hostname),
+            configuration: try .init(hostname: environment.redisHostname()),
             boundEventLoop: NIOSingletons.posixEventLoopGroup.any()
         )
         self.client = try await connection.get()
     }
 
-    // This hostname has to match the redir service name in app.yml.
-    static let hostname = "redis"
     static let maxConnectionAttempts = 3
 
     func set(key: String, value: String?, expiresIn: Duration?) async {