Don't use the daemonDir as a started hint

src/index.ts

@@ -1,24 +1,26 @@
 import { netrcPath, tailLog } from "./helpers.js";
 import * as actionsCore from "@actions/core";
 import { IdsToolbox, inputs } from "detsys-ts";
-import { mkdir, stat } from "fs/promises";
 import got, { Got } from "got";
 import * as http from "http";
 import { SpawnOptions, exec, spawn } from "node:child_process";
-import { openSync, readFileSync } from "node:fs";
+import { mkdirSync, openSync, readFileSync } from "node:fs";
 import * as fs from "node:fs/promises";
 import * as os from "node:os";
 import * as path from "node:path";
 import { inspect, promisify } from "node:util";
 
 const ENV_CACHE_DAEMONDIR = "MAGIC_NIX_CACHE_DAEMONDIR";
+const ENV_CACHE_STARTED = "MAGIC_NIX_CACHE_STARTED";
+
+const STARTED_HINT = "true";
 
 class MagicNixCacheAction {
   idslib: IdsToolbox;
   private client: Got;
 
-  private daemonDir?: string;
+  private daemonDir: string;
-  private unsafeDaemonDir: string;
+  private daemonStarted: boolean;
 
   constructor() {
     this.idslib = new IdsToolbox({
@@ -44,33 +46,22 @@ class MagicNixCacheAction {
       },
     });
 
+    this.daemonStarted = process.env[ENV_CACHE_STARTED] === STARTED_HINT;
+
     if (process.env[ENV_CACHE_DAEMONDIR]) {
-      this.unsafeDaemonDir = process.env[ENV_CACHE_DAEMONDIR];
+      this.daemonDir = process.env[ENV_CACHE_DAEMONDIR];
     } else {
-      this.unsafeDaemonDir = this.idslib.getTemporaryName();
+      this.daemonDir = this.idslib.getTemporaryName();
-      actionsCore.exportVariable(ENV_CACHE_DAEMONDIR, this.unsafeDaemonDir);
+      mkdirSync(this.daemonDir);
+      actionsCore.exportVariable(ENV_CACHE_DAEMONDIR, this.daemonDir);
     }
+
     this.idslib.stapleFile(
       "daemon.log",
-      path.join(this.unsafeDaemonDir, "daemon.log"),
+      path.join(this.daemonDir, "daemon.log"),
     );
   }
 
-  async getDaemonDir(): Promise<string> {
-    if (this.daemonDir === undefined) {
-      await mkdir(this.unsafeDaemonDir, { recursive: true });
-      this.daemonDir = this.unsafeDaemonDir;
-      return this.unsafeDaemonDir;
-    } else {
-      return this.daemonDir;
-    }
-  }
-
-  async daemonDirExists(): Promise<boolean> {
-    const statRes = await stat(this.unsafeDaemonDir);
-    return statRes.isDirectory();
-  }
-
   async setUpAutoCache(): Promise<void> {
     const requiredEnv = [
       "ACTIONS_CACHE_URL",
@@ -96,6 +87,8 @@ class MagicNixCacheAction {
       `GitHub Action Cache URL: ${process.env["ACTIONS_CACHE_URL"]}`,
     );
 
+    this.daemonStarted = true;
+    actionsCore.exportVariable(ENV_CACHE_STARTED, STARTED_HINT);
     const sourceBinary = inputs.getStringOrNull("source-binary");
     const daemonBin =
       sourceBinary !== null ? sourceBinary : await this.fetchAutoCacher();
@@ -134,10 +127,9 @@ class MagicNixCacheAction {
     });
 
     // Start tailing the daemon log.
-    const daemonDir = await this.getDaemonDir();
+    const outputPath = `${this.daemonDir}/daemon.log`;
-    const outputPath = `${daemonDir}/daemon.log`;
     const output = openSync(outputPath, "a");
-    const log = tailLog(daemonDir);
+    const log = tailLog(this.daemonDir);
     const netrc = await netrcPath();
     const nixConfPath = `${process.env["HOME"]}/.config/nix/nix.conf`;
 
@@ -192,7 +184,7 @@ class MagicNixCacheAction {
     // Start the server. Once it is ready, it will notify us via the notification server.
     const daemon = spawn(daemonBin, daemonCliFlags, opts);
 
-    const pidFile = path.join(daemonDir, "daemon.pid");
+    const pidFile = path.join(this.daemonDir, "daemon.pid");
     await fs.writeFile(pidFile, `${daemon.pid}`);
 
     actionsCore.info("Waiting for magic-nix-cache to start...");
@@ -239,7 +231,7 @@ class MagicNixCacheAction {
   }
 
   async notifyAutoCache(): Promise<void> {
-    if (!(await this.daemonDirExists())) {
+    if (!this.daemonStarted) {
       actionsCore.debug("magic-nix-cache not started - Skipping");
       return;
     }
@@ -259,20 +251,19 @@ class MagicNixCacheAction {
   }
 
   async tearDownAutoCache(): Promise<void> {
-    if (!(await this.daemonDirExists())) {
+    if (!this.daemonStarted) {
       actionsCore.debug("magic-nix-cache not started - Skipping");
       return;
     }
-    const daemonDir = await this.getDaemonDir();
 
-    const pidFile = path.join(daemonDir, "daemon.pid");
+    const pidFile = path.join(this.daemonDir, "daemon.pid");
     const pid = parseInt(await fs.readFile(pidFile, { encoding: "ascii" }));
     actionsCore.debug(`found daemon pid: ${pid}`);
     if (!pid) {
       throw new Error("magic-nix-cache did not start successfully");
     }
 
-    const log = tailLog(daemonDir);
+    const log = tailLog(this.daemonDir);
 
     try {
       actionsCore.debug(`about to post to localhost`);
@@ -296,7 +287,7 @@ class MagicNixCacheAction {
     } finally {
       if (actionsCore.isDebug()) {
         actionsCore.info("Entire log:");
-        const entireLog = readFileSync(path.join(daemonDir, "daemon.log"));
+        const entireLog = readFileSync(path.join(this.daemonDir, "daemon.log"));
         actionsCore.info(entireLog.toString());
       }
     }