Merge pull request #146 from yz89122/fix/helm/cache-empty-index-file

fix(helm): cache empty index file

.changeset/curvy-roses-unite.md

@@ -0,0 +1,5 @@
+---
+"@kosko/helm": patch
+---
+
+Fix loadHelm might read empty index file in case of race condition

packages/helm/src/__tests__/load.ts

@@ -3,7 +3,7 @@ import { loadChart } from "../load";
 import { join } from "node:path";
 import { spawn } from "@kosko/exec-utils";
 import tmp from "tmp-promise";
-import { readdir } from "node:fs/promises";
+import { readdir, writeFile } from "node:fs/promises";
 import { Pod } from "kubernetes-models/v1/Pod";
 import { Manifest } from "@kosko/yaml";
 
@@ -484,3 +484,38 @@ describe("cache reuse", () => {
     expect(getPullCalls()).toHaveLength(2);
   });
 });
+
+describe("when index file is empty", () => {
+  let tmpDir: tmp.DirectoryResult;
+
+  beforeEach(async () => {
+    tmpDir = await tmp.dir({ unsafeCleanup: true });
+  });
+
+  afterEach(async () => {
+    await tmpDir.cleanup();
+  });
+
+  test("should not use cache", async () => {
+    const run = async () => {
+      const result = loadChart({
+        chart: "prometheus",
+        repo: "https://prometheus-community.github.io/helm-charts",
+        version: "13.6.0",
+        cache: { dir: tmpDir.path }
+      });
+
+      await expect(result()).resolves.not.toBeEmpty();
+    };
+
+    await run();
+
+    const filenames = await readdir(tmpDir.path);
+    const indexFilename = filenames.find((filename) =>
+      filename.startsWith("index")
+    );
+    await writeFile(join(tmpDir.path, indexFilename!), "");
+
+    await run();
+  });
+});

packages/helm/src/load.ts

@@ -352,7 +352,10 @@ async function pullChart(options: PullOptions): Promise<string | undefined> {
   // Read the index file to get the cache path
   try {
     const content = await readFile(indexPath, "utf8");
-    return join(cacheDir, content);
+    if (content) {
+      // The content read by current process might be empty due to race condition.
+      return join(cacheDir, content);
+    }
   } catch (err) {
     if (getErrorCode(err) !== "ENOENT") throw err;
   }