Use a pool of gpg key servers

__tests__/gpg.test.ts

@@ -0,0 +1,47 @@
+import * as exec from "@actions/exec";
+import { setupKeys, verify, refreshKeys } from "../src/gpg";
+
+jest.mock("@actions/exec");
+
+const mockExec = exec.exec as jest.Mock;
+
+describe("gpg", () => {
+  afterEach(() => {
+    mockExec.mockClear();
+  });
+
+  it("uses the first responding keyserver in the pool", async () => {
+    mockExec.mockImplementation(() => Promise.resolve(0));
+    await refreshKeys();
+    expect(mockExec).toBeCalledTimes(1);
+  });
+
+  it("uses the next keyserver in the pool if the previous fails", async () => {
+    const failingServers = 3;
+    let testedServers = 0;
+
+    mockExec.mockImplementation(() => {
+      testedServers++;
+      if (testedServers >= failingServers) {
+        return Promise.resolve(0);
+      } else {
+        return Promise.resolve(1);
+      }
+    });
+
+    await refreshKeys();
+    expect(mockExec).toBeCalledTimes(3);
+  });
+
+  it("throws an error if all servers in the pool fails", async () => {
+    mockExec.mockImplementation(() => Promise.resolve(1));
+
+    try {
+      await refreshKeys();
+    } catch (e) {
+      expect(e).toEqual(
+        new Error("Failed to refresh keys from any server in the pool.")
+      );
+    }
+  });
+});

src/gpg.ts

@@ -0,0 +1,53 @@
+import { exec } from "@actions/exec";
+import * as core from "@actions/core";
+import * as toolCache from "@actions/tool-cache";
+
+export async function setupKeys() {
+  core.debug("Fetching verification keys");
+  let path = await toolCache.downloadTool(
+    "https://swift.org/keys/all-keys.asc"
+  );
+
+  core.debug("Importing verification keys");
+  await exec(`gpg --import "${path}"`);
+
+  core.debug("Refreshing keys");
+  await refreshKeys();
+}
+
+export async function verify(signaturePath: string, packagePath: string) {
+  core.debug("Verifying signature");
+  await exec("gpg", ["--verify", signaturePath, packagePath]);
+}
+
+export async function refreshKeys() {
+  const pool = [
+    "hkp://pool.sks-keyservers.net",
+    "ha.pool.sks-keyservers.net",
+    "keyserver.ubuntu.com",
+    "hkp://keyserver.ubuntu.com",
+    "pgp.mit.edu",
+  ];
+
+  for (const server of pool) {
+    core.debug(`Refreshing keys from ${server}`);
+    if (await refreshKeysFromServer(server)) {
+      core.debug(`Refresh successful`);
+      return;
+    }
+    core.debug(`Refresh failed`);
+  }
+
+  throw new Error("Failed to refresh keys from any server in the pool.");
+}
+
+function refreshKeysFromServer(server: string): Promise<boolean> {
+  return exec(`gpg --keyserver ${server} --refresh-keys Swift`)
+    .then((code) => code === 0)
+    .catch((error) => {
+      core.warning(
+        `An error occurred when trying to refresh keys from ${server}: ${error}`
+      );
+      return false;
+    });
+}

src/linux-install.ts

@@ -5,6 +5,7 @@ import * as core from "@actions/core";
 import * as toolCache from "@actions/tool-cache";
 import { System } from "./os";
 import { swiftPackage, Package } from "./swift-versions";
+import { setupKeys, verify } from "./gpg";
 
 export async function install(version: string, system: System) {
   if (os.platform() !== "linux") {
@@ -66,21 +67,3 @@ async function unpack(
   core.debug("Package cached");
   return cachedPath;
 }
-
-async function setupKeys() {
-  core.debug("Fetching verification keys");
-  let path = await toolCache.downloadTool(
-    "https://swift.org/keys/all-keys.asc"
-  );
-  core.debug("Importing verification keys");
-  await exec(`gpg --import "${path}"`);
-  core.debug("Refreshing keys");
-  await exec(
-    "gpg --keyserver hkp://pool.sks-keyservers.net --refresh-keys Swift"
-  );
-}
-
-async function verify(signaturePath: string, packagePath: string) {
-  core.debug("Verifying signature");
-  await exec("gpg", ["--verify", signaturePath, packagePath]);
-}