App Hosting: add github branch validation

src/apphosting/githubConnections.spec.ts

@@ -395,4 +395,54 @@ describe("githubConnections", () => {
       expect(promptOnceStub).to.be.called;
     });
   });
+  describe("promptGitHubBranch", () => {
+    const sandbox: sinon.SinonSandbox = sinon.createSandbox();
+
+    let promptOnceStub: sinon.SinonStub;
+    let listAllBranchesStub: sinon.SinonStub;
+
+    beforeEach(() => {
+      promptOnceStub = sandbox.stub(prompt, "promptOnce").throws("Unexpected promptOnce call");
+      listAllBranchesStub = sandbox
+        .stub(devconnect, "listAllBranches")
+        .throws("Unexpected listAllBranches call");
+    });
+
+    afterEach(() => {
+      sandbox.verifyAndRestore();
+    });
+
+    it("prompts user for branch", async () => {
+      listAllBranchesStub.returns(new Set(["main", "test1"]));
+
+      promptOnceStub.onFirstCall().returns("main");
+      const testRepoLink = {
+        name: "test",
+        cloneUri: "/test",
+        createTime: "",
+        updateTime: "",
+        deleteTime: "",
+        reconciling: false,
+        uid: "",
+      };
+      await expect(repo.promptGitHubBranch(testRepoLink)).to.eventually.equal("main");
+    });
+
+    it("re-prompts if user enters a branch that does not exist in given repo", async () => {
+      listAllBranchesStub.returns(new Set(["main", "test1"]));
+
+      promptOnceStub.onFirstCall().returns("not-main");
+      promptOnceStub.onSecondCall().returns("test1");
+      const testRepoLink = {
+        name: "test",
+        cloneUri: "/test",
+        createTime: "",
+        updateTime: "",
+        deleteTime: "",
+        reconciling: false,
+        uid: "",
+      };
+      await expect(repo.promptGitHubBranch(testRepoLink)).to.eventually.equal("test1");
+    });
+  });
 });

src/apphosting/githubConnections.ts

@@ -22,7 +22,7 @@
 const APPHOSTING_CONN_PATTERN = /.+\/apphosting-github-conn-.+$/;
 const APPHOSTING_OAUTH_CONN_NAME = "firebase-app-hosting-github-oauth";
 const CONNECTION_NAME_REGEX =
   /^projects\/(?<projectId>[^\/]+)\/locations\/(?<location>[^\/]+)\/connections\/(?<id>[^\/]+)$/;
 
 /**
  * Exported for unit testing.
@@ -127,7 +127,7 @@
   } while (repoCloneUri === ADD_CONN_CHOICE);
 
   // Ensure that the selected connection exists in the same region as the backend
   const { id: connectionId } = parseConnectionName(connection.name)!;
   await getOrCreateConnection(projectId, location, connectionId, {
     authorizerCredential: connection.githubConfig?.authorizerCredential,
     appInstallationId: connection.githubConfig?.appInstallationId,
@@ -192,7 +192,7 @@
   try {
     conn = await devConnect.getConnection(projectId, location, APPHOSTING_OAUTH_CONN_NAME);
   } catch (err: unknown) {
     if ((err as any).status === 404) {
       // Cloud build P4SA requires the secret manager admin role.
       // This is required when creating an initial connection which is the Oauth connection in our case.
       await ensureSecretManagerAdminGrant(projectId);
@@ -214,7 +214,7 @@
       message: "Press Enter once you have authorized the GitHub App.",
     });
     cleanup();
     const { projectId, location, id } = parseConnectionName(conn.name)!;
     conn = await devConnect.getConnection(projectId, location, id);
   }
   utils.logSuccess("Connected with GitHub successfully\n");
@@ -231,7 +231,7 @@
     type: "autocomplete",
     name: "cloneUri",
     message: "Which GitHub repo do you want to deploy?",
     source: (_: any, input = ""): Promise<(inquirer.DistinctChoice | inquirer.Separator)[]> => {
       return new Promise((resolve) =>
         resolve([
           new inquirer.Separator(),
@@ -257,6 +257,30 @@
   return { cloneUri, connection: cloneUriToConnection[cloneUri] };
 }
 
+/**
+ * Prompts the user for a GitHub branch and validates that the given branch
+ * actually exists. User is re-prompted until they enter a valid branch.
+ */
+export async function promptGitHubBranch(repoLink: devConnect.GitRepositoryLink) {
+  const branches = await devConnect.listAllBranches(repoLink.name);
+  while (true) {
+    const branch = await promptOnce({
+      name: "branch",
+      type: "input",
+      default: "main",
+      message: "Pick a branch for continuous deployment",
+    });
+
+    if (branches.has(branch)) {
+      return branch;
+    }
+
+    utils.logWarning(
+      `The branch "${branch}" does not exist on "${extractRepoSlugFromUri(repoLink.cloneUri)}". Please enter a valid branch for this repo.`,
+    );
+  }
+}
+
 /**
  * Exported for unit testing
  */

src/apphosting/index.ts

@@ -97,7 +97,7 @@ export async function doSetup(
   location =
     location || (await promptLocation(projectId, "Select a location to host your backend:\n"));
 
-  const gitRepositoryConnection: GitRepositoryLink = await githubConnections.linkGitHubRepository(
+  const gitRepositoryLink: GitRepositoryLink = await githubConnections.linkGitHubRepository(
     projectId,
     location,
   );
@@ -112,12 +112,7 @@ export async function doSetup(
   // TODO: Once tag patterns are implemented, prompt which method the user
   // prefers. We could reduce the number of questions asked by letting people
   // enter tag:<pattern>?
-  const branch = await promptOnce({
-    name: "branch",
-    type: "input",
-    default: "main",
-    message: "Pick a branch for continuous deployment",
-  });
+  const branch = await githubConnections.promptGitHubBranch(gitRepositoryLink);
   logSuccess(`Repo linked successfully!\n`);
 
   logBullet(`${clc.yellow("===")} Set up your backend`);
@@ -139,7 +134,7 @@ export async function doSetup(
     projectId,
     location,
     backendId,
-    gitRepositoryConnection,
+    gitRepositoryLink,
     serviceAccount,
     webApp?.id,
     rootDir,

src/gcp/devConnect.ts

@@ -234,6 +234,39 @@ export async function listAllLinkableGitRepositories(
   return repos;
 }
 
+/**
+ * Lists all branches for a given repo. Returns a set of branches.
+ */
+
+export async function listAllBranches(repoLinkName: string): Promise<Set<string>> {
+  const branches = new Set<string>();
+
+  const getNextPage = async (pageToken = ""): Promise<void> => {
+    const res = await client.get<{
+      refNames: string[];
+      nextPageToken?: string;
+    }>(`${repoLinkName}:fetchGitRefs`, {
+      queryParams: {
+        refType: "BRANCH",
+        pageSize: PAGE_SIZE_MAX,
+        pageToken,
+      },
+    });
+    if (Array.isArray(res.body.refNames)) {
+      res.body.refNames.forEach((branch) => {
+        branches.add(branch);
+      });
+    }
+    if (res.body.nextPageToken) {
+      await getNextPage(res.body.nextPageToken);
+    }
+  };
+
+  await getNextPage();
+
+  return branches;
+}
+
 /**
  * Creates a GitRepositoryLink.Upon linking a Git Repository, Developer
  * Connect will configure the Git Repository to send webhook events to

src/gcp/devconnect.spec.ts

@@ -104,4 +104,41 @@ describe("developer connect", () => {
       expect(conns).to.deep.equal([firstRepo, secondRepo, thirdRepo]);
     });
   });
+
+  describe("listAllBranches", () => {
+    it("interates through all pages and returns a single list and map", async () => {
+      const firstBranch = "test";
+      const secondBranch = "test2";
+      const thirdBranch = "test3";
+
+      get
+        .onFirstCall()
+        .returns({
+          body: {
+            refNames: [firstBranch],
+            nextPageToken: "someToken",
+          },
+        })
+        .onSecondCall()
+        .returns({
+          body: {
+            refNames: [secondBranch],
+            nextPageToken: "someToken2",
+          },
+        })
+        .onThirdCall()
+        .returns({
+          body: {
+            refNames: [thirdBranch],
+          },
+        });
+
+      const branches = await devconnect.listAllBranches(
+        "/projects/blah/locations/us-central1/connections/blah",
+      );
+      expect(get).callCount(3);
+
+      expect(branches).to.deep.equal(new Set([firstBranch, secondBranch, thirdBranch]));
+    });
+  });
 });