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Created December 2, 2025 07:38
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Migrating Attachments From GitLab To Forgejo After Migration

GitLab to Forgejo Attachment Migrator

This script migrates attachments from GitLab issues to their corresponding Forgejo issues, addressing the limitation in Forgejo's GitLab importer that doesn't handle attachments.

Problem Solved

The standard Forgejo GitLab importer only imports metadata (issues, comments, etc.) but does not import attachments. This leaves issues with broken image links and missing files, making visual content unusable after migration.

How It Works

  1. Downloads attachments from GitLab issues using URL scraping (since GitLab API doesn't provide attachment download endpoints)
  2. Uploads attachments to Forgejo using the API
  3. Updates issue content by replacing old GitLab URLs with new Forgejo URLs
  4. Handles all content including issue descriptions and comments

Installation

pip install -r requirements.txt

Configuration

Set the following environment variables:

export GITLAB_TOKEN="your_gitlab_api_token"
export FORGEJO_TOKEN="your_forgejo_api_token"
export GITLAB_PROJECT_ID="group/project"  # or numeric ID
export FORGEJO_OWNER="your_username"
export FORGEJO_REPO="your_repo_name"

# Optional (defaults shown)
export GITLAB_URL="https://gitlab.com"
export FORGEJO_URL="https://codeberg.org"

Getting API Tokens

GitLab Token:

  1. Go to GitLab → User Settings → Access Tokens
  2. Create token with api scope
  3. Copy the token value

Forgejo Token:

  1. Go to Forgejo → User Settings → Applications
  2. Generate New Token with repository access
  3. Copy the token value

Usage

python gitlab_to_forgejo_attachments.py

Example Migration

For an issue like this Codeberg issue that contains logo design sketches and images, the script will:

  1. Find all image URLs in the issue content
  2. Download each attachment from GitLab
  3. Upload to Forgejo
  4. Replace URLs like /uploads/abc123.../logo.png with new Forgejo URLs
  5. Update the issue description with the new URLs

Output

The script provides detailed logging and final statistics:

2025-11-21 10:30:15 - INFO - Starting GitLab to Forgejo attachment migration...
2025-11-21 10:30:15 - INFO - GitLab: https://gitlab.com/my-project
2025-11-21 10:30:15 - INFO - Forgejo: https://codeberg.org/user/repo
2025-11-21 10:30:16 - INFO - Found 25 issues in project my-project
2025-11-21 10:30:17 - INFO - Processing GitLab issue #1: Logo design discussion
2025-11-21 10:30:18 - INFO - Found 4 attachments in issue #1
2025-11-21 10:30:19 - INFO - Downloaded attachment: logo-sketch-1.png
2025-11-21 10:30:20 - INFO - Uploaded logo-sketch-1.png to Forgejo: https://codeberg.org/attachments/...
...
2025-11-21 10:35:22 - INFO - Migration completed!
2025-11-21 10:35:22 - INFO - Issues processed: 25
2025-11-21 10:35:22 - INFO - Attachments migrated: 47
2025-11-21 10:35:22 - INFO - Attachments failed: 2
2025-11-21 10:35:22 - INFO - Issues updated: 12

Limitations

  • Only works with issues that have already been migrated (metadata must exist in Forgejo)
  • Assumes 1:1 mapping between GitLab and Forgejo issue numbers
  • GitLab attachment URLs must follow standard /uploads/ pattern
  • Requires API access to both GitLab and Forgejo instances

Use Cases

Perfect for:

  • Post-migration cleanup when standard Forgejo import missed attachments
  • Retroactive fixing of broken image links in migrated repositories
  • Visual content preservation (logos, screenshots, diagrams, etc.)
  • Issues with embedded images that are essential for understanding context

Security Notes

  • Uses authenticated API calls for both GitLab and Forgejo
  • Downloads files temporarily in memory (no local file storage)
  • Respects API rate limits with proper error handling
  • Tokens should have minimal required permissions (read for GitLab, write for Forgejo)
#!/usr/bin/env python3
"""
GitLab to Forgejo Attachment Migration Script
This script downloads attachments from GitLab issues and uploads them to
corresponding Forgejo issues, updating the URLs in the process.
Dependencies:
pip install python-gitlab pyforgejo requests
"""
import os
import re
import sys
import logging
import requests
from pathlib import Path
from urllib.parse import urlparse, urljoin
from typing import Dict, List, Tuple, Optional
import tempfile
import mimetypes
import gitlab
from pyforgejo import PyforgejoApi
# Configure logging
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')
logger = logging.getLogger(__name__)
class GitLabToForgejoAttachmentMigrator:
"""Migrates attachments from GitLab issues to Forgejo issues."""
def __init__(self, gitlab_url: str, gitlab_token: str,
forgejo_url: str, forgejo_token: str):
"""
Initialize the migrator.
Args:
gitlab_url: GitLab instance URL (e.g., 'https://gitlab.com')
gitlab_token: GitLab API token
forgejo_url: Forgejo instance URL (e.g., 'https://codeberg.org')
forgejo_token: Forgejo API token
"""
self.gitlab_url = gitlab_url.rstrip('/')
self.gitlab_token = gitlab_token
self.forgejo_url = forgejo_url.rstrip('/')
self.forgejo_token = forgejo_token
# Initialize GitLab client
self.gitlab = gitlab.Gitlab(gitlab_url, private_token=gitlab_token)
# Initialize Forgejo client (using direct API since pyforgejo might need configuration)
self.session = requests.Session()
self.session.headers.update({
'Authorization': f'token {forgejo_token}',
'Content-Type': 'application/json'
})
# Pattern to match GitLab upload URLs
self.upload_pattern = re.compile(r'(/uploads/[a-f0-9]{32}/[^)\s]+)')
def get_gitlab_project(self, project_id: str) -> gitlab.v4.objects.Project:
"""Get GitLab project by ID or path."""
try:
return self.gitlab.projects.get(project_id)
except gitlab.exceptions.GitlabGetError:
logger.error(f"Could not find GitLab project: {project_id}")
raise
def get_project_issues(self, project: gitlab.v4.objects.Project) -> List:
"""Get all issues from a GitLab project."""
try:
issues = project.issues.list(all=True, state='all')
logger.info(f"Found {len(issues)} issues in project {project.name}")
return issues
except gitlab.exceptions.GitlabGetError as e:
logger.error(f"Error fetching issues: {e}")
return []
def find_attachments_in_text(self, text: str) -> List[str]:
"""
Find all GitLab upload URLs in text content.
Args:
text: Issue description or comment text
Returns:
List of upload URLs found in the text
"""
if not text:
return []
matches = self.upload_pattern.findall(text)
return matches
def download_attachment(self, project: gitlab.v4.objects.Project,
upload_path: str) -> Tuple[Optional[bytes], Optional[str]]:
"""
Download an attachment from GitLab.
Args:
project: GitLab project object
upload_path: Upload path (e.g., '/uploads/abc123.../file.png')
Returns:
Tuple of (file_content, filename) or (None, None) if failed
"""
try:
# Construct full URL using GitLab's project ID format
full_url = f"{self.gitlab_url}/-/project/{project.id}{upload_path}"
logger.info(f"Attempting to download: {full_url}")
# Download with authentication
headers = {'Private-Token': self.gitlab_token}
response = requests.get(full_url, headers=headers, stream=True)
if response.status_code == 200:
filename = os.path.basename(upload_path)
logger.info(f"✅ Downloaded attachment: {filename}")
return response.content, filename
else:
logger.warning(f"❌ Failed to download {upload_path}: HTTP {response.status_code}")
logger.warning(f" Full URL attempted: {full_url}")
return None, None
except Exception as e:
logger.error(f"Error downloading {upload_path}: {e}")
return None, None
def upload_to_forgejo(self, forgejo_owner: str, forgejo_repo: str,
file_content: bytes, filename: str, issue_number: int) -> Optional[str]:
"""
Upload a file to Forgejo and return the new URL.
Args:
forgejo_owner: Forgejo repository owner
forgejo_repo: Forgejo repository name
file_content: File content as bytes
filename: Original filename
issue_number: Forgejo issue number to attach to
Returns:
New Forgejo URL or None if failed
"""
try:
# Prepare the upload - try different parameter names that Forgejo might expect
files = {
'attachment': (filename, file_content, self._get_content_type(filename))
}
# Upload to Forgejo (using the issue assets API endpoint)
upload_url = f"{self.forgejo_url}/api/v1/repos/{forgejo_owner}/{forgejo_repo}/issues/{issue_number}/assets"
logger.info(f"Attempting to upload to: {upload_url}")
# Create clean session for file upload (no JSON content-type)
upload_session = requests.Session()
upload_session.headers.update({
'Authorization': f'token {self.forgejo_token}'
})
# Log detailed request info
logger.info(f"Request details:")
logger.info(f" - Method: POST")
logger.info(f" - URL: {upload_url}")
logger.info(f" - Headers: {upload_session.headers}")
logger.info(f" - File size: {len(file_content)} bytes")
logger.info(f" - Content-Type: {self._get_content_type(filename)}")
response = upload_session.post(upload_url, files=files)
# Log detailed response info
logger.info(f"Response details:")
logger.info(f" - Status: {response.status_code}")
logger.info(f" - Headers: {dict(response.headers)}")
logger.info(f" - Body: {response.text}")
if response.status_code == 201:
upload_data = response.json()
new_url = upload_data.get('browser_download_url') or upload_data.get('download_url')
logger.info(f"✅ Uploaded {filename} to Forgejo: {new_url}")
return new_url
else:
logger.error(f"❌ Upload failed for {filename}:")
logger.error(f" Status: {response.status_code}")
logger.error(f" Response: {response.text}")
logger.error(f" Headers: {dict(response.headers)}")
return None
except Exception as e:
logger.error(f"Error uploading {filename} to Forgejo: {e}")
return None
def _get_content_type(self, filename: str) -> str:
"""Get MIME type for a filename."""
content_type, _ = mimetypes.guess_type(filename)
return content_type or 'application/octet-stream'
def update_forgejo_issue(self, forgejo_owner: str, forgejo_repo: str,
issue_number: int, new_content: str) -> bool:
"""
Update a Forgejo issue with new content.
Args:
forgejo_owner: Forgejo repository owner
forgejo_repo: Forgejo repository name
issue_number: Issue number
new_content: Updated content with new URLs
Returns:
True if successful, False otherwise
"""
try:
update_url = f"{self.forgejo_url}/api/v1/repos/{forgejo_owner}/{forgejo_repo}/issues/{issue_number}"
data = {'body': new_content}
response = self.session.patch(update_url, json=data)
if response.status_code == 201:
logger.info(f"Updated Forgejo issue #{issue_number}")
return True
else:
logger.error(f"Failed to update issue #{issue_number}: {response.status_code} - {response.text}")
return False
except Exception as e:
logger.error(f"Error updating Forgejo issue #{issue_number}: {e}")
return False
def migrate_issue_attachments(self, gitlab_project_id: str,
forgejo_owner: str, forgejo_repo: str,
issue_mapping: Optional[Dict[int, int]] = None) -> Dict[str, int]:
"""
Migrate attachments for all issues from GitLab to Forgejo.
Args:
gitlab_project_id: GitLab project ID or path
forgejo_owner: Forgejo repository owner
forgejo_repo: Forgejo repository name
issue_mapping: Optional mapping of GitLab issue IID to Forgejo issue number
If not provided, assumes 1:1 mapping
Returns:
Dictionary with migration statistics
"""
stats = {
'issues_processed': 0,
'attachments_migrated': 0,
'attachments_failed': 0,
'issues_updated': 0
}
# Get GitLab project
try:
project = self.get_gitlab_project(gitlab_project_id)
except Exception:
return stats
# Get all issues
issues = self.get_project_issues(project)
for issue in issues:
stats['issues_processed'] += 1
logger.info(f"Processing GitLab issue #{issue.iid}: {issue.title}")
# Find attachments in issue description
attachments = self.find_attachments_in_text(issue.description)
# Also check comments for attachments
try:
notes = issue.notes.list(all=True)
for note in notes:
attachments.extend(self.find_attachments_in_text(note.body))
except Exception as e:
logger.warning(f"Could not fetch comments for issue #{issue.iid}: {e}")
if not attachments:
logger.info(f"No attachments found in issue #{issue.iid}")
continue
logger.info(f"Found {len(attachments)} attachments in issue #{issue.iid}")
# Determine Forgejo issue number upfront
forgejo_issue_num = issue_mapping.get(issue.iid, issue.iid) if issue_mapping else issue.iid
# Process each attachment
url_mapping = {}
for attachment_path in attachments:
file_content, filename = self.download_attachment(project, attachment_path)
if file_content and filename:
new_url = self.upload_to_forgejo(forgejo_owner, forgejo_repo,
file_content, filename, forgejo_issue_num)
if new_url:
url_mapping[attachment_path] = new_url
stats['attachments_migrated'] += 1
else:
stats['attachments_failed'] += 1
else:
stats['attachments_failed'] += 1
# Update Forgejo issue if we have URL mappings
if url_mapping:
# Replace URLs in issue description
new_description = issue.description
for old_url, new_url in url_mapping.items():
new_description = new_description.replace(old_url, new_url)
# Update the Forgejo issue
if self.update_forgejo_issue(forgejo_owner, forgejo_repo,
forgejo_issue_num, new_description):
stats['issues_updated'] += 1
return stats
def main():
"""Main entry point for the script."""
# Configuration - you can modify these or use environment variables
GITLAB_URL = os.getenv('GITLAB_URL', 'https://gitlab.com')
GITLAB_TOKEN = os.getenv('GITLAB_TOKEN')
FORGEJO_URL = os.getenv('FORGEJO_URL', 'https://codeberg.org')
FORGEJO_TOKEN = os.getenv('FORGEJO_TOKEN')
# Project configuration
GITLAB_PROJECT_ID = os.getenv('GITLAB_PROJECT_ID') # e.g., 'group/project' or '12345'
FORGEJO_OWNER = os.getenv('FORGEJO_OWNER') # e.g., 'username'
FORGEJO_REPO = os.getenv('FORGEJO_REPO') # e.g., 'repo-name'
# Validate required environment variables
required_vars = [
('GITLAB_TOKEN', GITLAB_TOKEN),
('FORGEJO_TOKEN', FORGEJO_TOKEN),
('GITLAB_PROJECT_ID', GITLAB_PROJECT_ID),
('FORGEJO_OWNER', FORGEJO_OWNER),
('FORGEJO_REPO', FORGEJO_REPO)
]
missing_vars = [var_name for var_name, var_value in required_vars if not var_value]
if missing_vars:
logger.error(f"Missing required environment variables: {', '.join(missing_vars)}")
logger.info("Set the following environment variables:")
logger.info("GITLAB_TOKEN - GitLab API token")
logger.info("FORGEJO_TOKEN - Forgejo API token")
logger.info("GITLAB_PROJECT_ID - GitLab project ID or path (e.g., 'group/project')")
logger.info("FORGEJO_OWNER - Forgejo repository owner")
logger.info("FORGEJO_REPO - Forgejo repository name")
logger.info("Optional: GITLAB_URL, FORGEJO_URL")
sys.exit(1)
# Create migrator
migrator = GitLabToForgejoAttachmentMigrator(
gitlab_url=GITLAB_URL,
gitlab_token=GITLAB_TOKEN,
forgejo_url=FORGEJO_URL,
forgejo_token=FORGEJO_TOKEN
)
logger.info("Starting GitLab to Forgejo attachment migration...")
logger.info(f"GitLab: {GITLAB_URL}/{GITLAB_PROJECT_ID}")
logger.info(f"Forgejo: {FORGEJO_URL}/{FORGEJO_OWNER}/{FORGEJO_REPO}")
# Run migration
try:
stats = migrator.migrate_issue_attachments(
gitlab_project_id=GITLAB_PROJECT_ID,
forgejo_owner=FORGEJO_OWNER,
forgejo_repo=FORGEJO_REPO
)
# Print results
logger.info("Migration completed!")
logger.info(f"Issues processed: {stats['issues_processed']}")
logger.info(f"Attachments migrated: {stats['attachments_migrated']}")
logger.info(f"Attachments failed: {stats['attachments_failed']}")
logger.info(f"Issues updated: {stats['issues_updated']}")
except KeyboardInterrupt:
logger.info("Migration interrupted by user")
sys.exit(1)
except Exception as e:
logger.error(f"Migration failed: {e}")
sys.exit(1)
if __name__ == "__main__":
main()
python-gitlab>=4.0.0
pyforgejo>=2.0.0
requests>=2.25.0
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