Skeletal tail worker

infra/workers/README.md

@@ -33,3 +33,8 @@ To import an existing worker from the Cloudflare dashboard, use
 ```sh
 npm create cloudflare@2 existing-worker-name -- --type pre-existing --existing-script existing-worker-name
 ```
+
+## Logging
+
+Attach our tail worker (called `tail`) to your worker. Then, any `console.log`
+statements called by your worker will be forwarded to Grafana.

infra/workers/tail/package.json

@@ -0,0 +1,10 @@
+{
+    "name": "tail",
+    "private": true,
+    "devDependencies": {
+        "@cloudflare/workers-types": "^4.20240614.0",
+        "typescript": "^5",
+        "wrangler": "^3"
+    },
+    "packageManager": "yarn@1.22.22"
+}

infra/workers/tail/src/index.ts

@@ -0,0 +1,19 @@
+/**
+ * A tail worker that forwards all `console.log`s to Loki.
+ *
+ * https://developers.cloudflare.com/workers/observability/logging/tail-workers/
+ */
+export default {
+    async tail(events: TailItems[], env: Env) {
+        // If the tail worker itself throws an exception (it shouldn't, unless
+        // Loki is down), we don't catch it so that it counts as an "error" in
+        // the worker stats.
+        return handleTail(events, env.LOKI_URL);
+    },
+} satisfies ExportedHander<Env>;
+
+interface Env {
+    LOKI_URL: string;
+}
+
+const handleTail = (events: TailItems[], lokiURL: string) => {};

infra/workers/tail/tsconfig.json

@@ -0,0 +1 @@
+{ "extends": "../tsconfig.base.json", "include": ["src"] }

infra/workers/tail/wrangler.toml

@@ -0,0 +1,7 @@
+name = "tail"
+main = "src/index.ts"
+compatibility_date = "2024-06-14"
+
+[vars]
+# Added as a secret via the Cloudflare dashboard
+# LOKI_URL = "https://discord.com/api/webhooks/{webhook.id}/{webhook.token}"