Remove authentication requirement for download GitHub databases

This makes authentication for download GitHub CodeQL databases optional.
If you are already authenticated, your token will be used. If you are
not authenticated, an anonymous request will be made.

If the canary flag is enabled, you will be prompted for credentials when
downloading a database and you are not yet logged in.

extensions/ql-vscode/src/authentication.ts

@@ -76,16 +76,27 @@ export class Credentials {
     }));
   }
 
-  async getOctokit(): Promise<Octokit.Octokit> {
+  /**
+   * Creates or returns an instance of Octokit.
+   *
+   * @param requireAuthentication Whether the Octokit instance needs to be authentication as user.
+   * @returns An instance of Octokit.
+   */
+  async getOctokit(requireAuthentication = true): Promise<Octokit.Octokit> {
     if (this.octokit) {
       return this.octokit;
     }
 
-    this.octokit = await this.createOctokit(true);
-    // octokit shouldn't be undefined, since we've set "createIfNone: true".
-    // The following block is mainly here to prevent a compiler error.
+    this.octokit = await this.createOctokit(requireAuthentication);
+
     if (!this.octokit) {
-      throw new Error('Did not initialize Octokit.');
+      if (requireAuthentication) {
+        throw new Error('Did not initialize Octokit.');
+      }
+
+      // We don't want to set this in this.octokit because that would prevent
+      // authenticating when requireCredentials is true.
+      return new Octokit.Octokit({ retry });
     }
     return this.octokit;
   }

extensions/ql-vscode/src/databaseFetcher.ts

@@ -10,6 +10,7 @@ import {
 import { CodeQLCliServer } from './cli';
 import * as fs from 'fs-extra';
 import * as path from 'path';
+import * as Octokit from '@octokit/rest';
 
 import { DatabaseManager, DatabaseItem } from './databases';
 import {
@@ -23,6 +24,7 @@ import { logger } from './logging';
 import { tmpDir } from './helpers';
 import { Credentials } from './authentication';
 import { REPO_REGEX, getErrorMessage } from './pure/helpers-pure';
+import { isCanary } from './config';
 
 /**
  * Prompts a user to fetch a database from a remote location. Database is assumed to be an archive file.
@@ -99,14 +101,16 @@ export async function promptImportGithubDatabase(
     throw new Error(`Invalid GitHub repository: ${githubRepo}`);
   }
 
-  const result = await convertGithubNwoToDatabaseUrl(githubRepo, credentials, progress);
+  // Only require authentication if we are running with the canary flag enabled
+  const octokit = await credentials.getOctokit(isCanary());
+
+  const result = await convertGithubNwoToDatabaseUrl(githubRepo, octokit, progress);
   if (!result) {
     return;
   }
 
   const { databaseUrl, name, owner } = result;
 
-  const octokit = await credentials.getOctokit();
   /**
    * The 'token' property of the token object returned by `octokit.auth()`.
    * The object is undocumented, but looks something like this:
@@ -118,14 +122,9 @@ export async function promptImportGithubDatabase(
    * We only need the actual token string.
    */
   const octokitToken = (await octokit.auth() as { token: string })?.token;
-  if (!octokitToken) {
-    // Just print a generic error message for now. Ideally we could show more debugging info, like the
-    // octokit object, but that would expose a user token.
-    throw new Error('Unable to get GitHub token.');
-  }
   const item = await databaseArchiveFetcher(
     databaseUrl,
-    { 'Accept': 'application/zip', 'Authorization': `Bearer ${octokitToken}` },
+    { 'Accept': 'application/zip', 'Authorization': octokitToken ? `Bearer ${octokitToken}` : '' },
     databaseManager,
     storagePath,
     `${owner}/${name}`,
@@ -523,7 +522,7 @@ function convertGitHubUrlToNwo(githubUrl: string): string | undefined {
 
 export async function convertGithubNwoToDatabaseUrl(
   githubRepo: string,
-  credentials: Credentials,
+  octokit: Octokit.Octokit,
   progress: ProgressCallback): Promise<{
     databaseUrl: string,
     owner: string,
@@ -533,7 +532,6 @@ export async function convertGithubNwoToDatabaseUrl(
     const nwo = convertGitHubUrlToNwo(githubRepo) || githubRepo;
     const [owner, repo] = nwo.split('/');
 
-    const octokit = await credentials.getOctokit();
     const response = await octokit.request('GET /repos/:owner/:repo/code-scanning/codeql/databases', { owner, repo });
 
     const languages = response.data.map((db: any) => db.language);