Use browser cookie to download binary attachments from GitLab

Author: mdbenito

README.md

@@ -56,6 +56,10 @@ Go to [Settings / Access Tokens](https://gitlab.com/profile/personal_access_toke
 
 Leave it null for the first run of the script. Then the script will show you which projects there are. Can be either string or number.
 
+#### gitlab.sessionCookie
+
+GitLab's API [does not allow downloading of attachments](https://gitlab.com/gitlab-org/gitlab/-/issues/24155) and only images can be downloaded using HTTP. To work around this limitation and enable binary attachments to be migrated one can use the session cookie set in the browser after logging in to the gitlab instance. The cookie is named `_gitlab_session`.
+
 ### github
 
 #### github.baseUrl

sample_settings.ts

@@ -5,6 +5,7 @@ export default {
     // url: 'https://gitlab.mycompany.com',
     token: '{{gitlab private token}}',
     projectId: null,
+    sessionCookie: null,
   },
   github: {
     // baseUrl: 'https://gitlab.mycompany.com:123/etc',

src/gitlabHelper.ts

@@ -11,6 +11,7 @@ export default class GitlabHelper {
   gitlabUrl?: string;
   gitlabToken: string;
   gitlabProjectId: number;
+  sessionCookie: string;
 
   host: string;
   projectPath?: string;
@@ -24,6 +25,7 @@ export default class GitlabHelper {
     this.gitlabToken = gitlabSettings.token;
     this.gitlabProjectId = gitlabSettings.projectId;
     this.host = gitlabSettings.url ? gitlabSettings.url : 'http://gitlab.com';
+    this.sessionCookie = gitlabSettings.sessionCookie;
   }
 
   /**
@@ -92,7 +94,13 @@ export default class GitlabHelper {
     try {
       const host = this.host.endsWith('/') ? this.host : this.host + '/';
       const attachmentUrl = host + this.projectPath + relurl;
-      const data = (await axios.get(attachmentUrl, {responseType: 'arraybuffer'})).data;
+      const data = (await axios.get(attachmentUrl, {
+          responseType: 'arraybuffer',
+          headers: {
+            // HACK: work around GitLab's API lack of GET for attachments
+            // See https://gitlab.com/gitlab-org/gitlab/-/issues/24155
+            Cookie: `_gitlab_session=${this.sessionCookie}`
+          }})).data;
       return Buffer.from(data, 'binary')
     } catch (err) {
       console.error(`Could not download attachment #${relurl}.`);

src/settings.ts

@@ -42,6 +42,7 @@ export interface GitlabSettings {
   url?: string;
   token: string;
   projectId: number;
+  sessionCookie: string;
 }
 
 export interface S3Settings {