feat: retain application log history

packages/core/src/infrastructure/logs/constants.ts

@@ -1,6 +1,17 @@
 export const logLevels = ["error", "warn", "info", "debug"] as const;
 export type LogLevel = (typeof logLevels)[number];
 
+export interface LoggerMessage {
+  id: string;
+  timestamp: Date;
+  message: string;
+  level: LogLevel;
+}
+
+export const LOG_HISTORY_MAX_ENTRIES = 5_000;
+export const LOG_HISTORY_KEY = "list:logging:history";
+export const LOG_PUBLISH_CHANNEL = "pubSub:logging";
+
 export const logLevelConfiguration = {
   error: {
     prefix: "🔴",

packages/core/src/infrastructure/logs/transports/redis-transport.ts

@@ -1,8 +1,11 @@
-import superjson from "superjson";
+import { randomUUID } from "node:crypto";
+import { stringify } from "superjson";
 import Transport from "winston-transport";
 
 import type { RedisClient } from "../../redis/client";
 import { createRedisClient } from "../../redis/client";
+import type { LoggerMessage } from "../constants";
+import { LOG_HISTORY_KEY, LOG_HISTORY_MAX_ENTRIES, LOG_PUBLISH_CHANNEL } from "../constants";
 
 const messageSymbol = Symbol.for("message");
 const levelSymbol = Symbol.for("level");
@@ -13,12 +16,11 @@ const levelSymbol = Symbol.for("level");
 //
 export class RedisTransport extends Transport {
   private redis: RedisClient | null = null;
-  public static readonly publishChannel = "pubSub:logging";
 
   /**
-   * Log the info to the Redis channel
+   * Retain the log in a bounded Redis list and publish it to live subscribers.
    */
-  log(info: { [messageSymbol]: string; [levelSymbol]: string }, callback: () => void) {
+  log(info: { [messageSymbol]: string; [levelSymbol]: LoggerMessage["level"] }, callback: () => void) {
     setImmediate(() => {
       this.emit("logged", info);
     });
@@ -26,19 +28,23 @@ export class RedisTransport extends Transport {
     // Is only initialized here because it did not work when initialized in the constructor or outside the class
     this.redis ??= createRedisClient();
 
+    const message: LoggerMessage = {
+      id: randomUUID(),
+      timestamp: new Date(),
+      message: info[messageSymbol],
+      level: info[levelSymbol],
+    };
+    const serializedMessage = stringify(message);
+
     this.redis
-      .publish(
-        RedisTransport.publishChannel,
-        superjson.stringify({
-          message: info[messageSymbol],
-          level: info[levelSymbol],
-        }),
-      )
-      .then(() => {
-        callback();
-      })
+      .multi()
+      .lpush(LOG_HISTORY_KEY, serializedMessage)
+      .ltrim(LOG_HISTORY_KEY, 0, LOG_HISTORY_MAX_ENTRIES - 1)
+      .publish(LOG_PUBLISH_CHANNEL, serializedMessage)
+      .exec()
       .catch(() => {
         // Ignore errors
-      });
+      })
+      .finally(callback);
   }
 }