feat(shim): add nginx cache purger on pre-registration (#469)

* feat(shim): add nginx cache purger on pre-registration

* Don't fail on unlink failures

* Update deps

container/shim/package.json

@@ -17,7 +17,7 @@
     "express-async-handler": "^1.2.0",
     "fast-glob": "^3.3.1",
     "logfmt": "^1.3.2",
-    "lru-cache": "^10.0.0",
+    "lru-cache": "^10.0.1",
     "mime-types": "^2.1.35",
     "multiformats": "^12.0.1",
     "node-fetch": "^3.3.2",

container/shim/src/modules/registration.js

@@ -22,6 +22,7 @@ import { parseVersionNumber } from "../utils/version.js";
 import { orchestratorAgent } from "../utils/http.js";
 import { prefillCache } from "../utils/prefill.js";
 import { check } from "../lib/ocsp/check.js";
+import { purgeCacheFile } from "../utils/purger.js";
 
 const debug = Debug.extend("registration");
 
@@ -50,6 +51,13 @@ export async function register(initial = false) {
     preregisterResponse = await sendPreRegisterRequest(postOptions({ nodeId: NODE_ID }));
   }
 
+  if (preregisterResponse.filesToPurge) {
+    debug("Purging %d files", preregisterResponse.filesToPurge.length);
+    for (const file of preregisterResponse.filesToPurge) {
+      await purgeCacheFile(file);
+    }
+  }
+
   if (VERSION !== DEV_VERSION && initial && preregisterResponse?.speedtestRequired !== false) {
     let speedtest;
     try {
@@ -247,6 +255,16 @@ async function sendRegisterRequest(initial, registerOptions) {
   }
 }
 
+/**
+ * Sends a pre-registration request to the orchestrator.
+ *
+ * @typedef {object} PreRegisterResponse
+ * @property {boolean} speedtestRequired
+ * @property {string[]} filesToPurge
+ *
+ * @param {object} postOptions
+ * @returns {Promise<PreRegisterResponse>}
+ */
 async function sendPreRegisterRequest(postOptions) {
   debug("Pre-registering with orchestrator");
 

container/shim/src/utils/purger.js

@@ -0,0 +1,20 @@
+import fs from "node:fs/promises";
+import { createHash } from "node:crypto";
+import path from "node:path";
+import { debug } from "./logging.js";
+
+const CACHE_DIR = "/usr/src/app/shared/nginx_cache";
+
+export async function purgeCacheFile(key) {
+  debug("Purging cache file for key %s", key);
+  const cacheFilePath = keyToCacheFilePath(key);
+  await fs
+    .unlink(path.join(CACHE_DIR, cacheFilePath))
+    .catch((err) => debug("Failed to purge cache file: %s", err.message));
+}
+
+function keyToCacheFilePath(path) {
+  const hash = createHash("md5").update(path).digest("hex");
+
+  return `${hash.slice(-2)}/${hash.slice(-4, -2)}/${hash.slice(-6, -4)}/${hash}`;
+}