# Rollback

Roll forward to a previous version when a deploy misbehaves. There is no historical rollback command in v3: rolling back means applying and deploying a previous manifest or image reference. Redeploying a mutable tag (for example `latest`) does not guarantee the previous image bytes; keep immutable versioned tags.

## Roll Forward to a Previous Tag

The image tags are still in the registry. Point the app file at the last good tag, apply, deploy:

```bash
# 1. Edit blog.toml: image = "gordon.mydomain.com/myapp:v2.0.0"
gordon apps apply --file blog.toml --remote prod
gordon apps deploy blog --remote prod
```

A rollback deploy replaces services one at a time like any other deploy: a short service interruption is possible, and Gordon never runs two generations of the same service at the same time. If the replacement fails after the old container was removed, Gordon does not recreate it and does not promise automatic data rollback.

## Re-push the Previous Image as latest

When the app file tracks `latest`, re-tag and re-push, then deploy (deploy re-resolves mutable tags):

```bash
docker pull gordon.mydomain.com/myapp:v2.0.0
docker tag gordon.mydomain.com/myapp:v2.0.0 gordon.mydomain.com/myapp:latest
docker push gordon.mydomain.com/myapp:latest
gordon apps deploy blog --remote prod
```

## Version Management

### Keep Previous Versions

Always push versioned tags alongside `latest`:

```bash
VERSION=$(git describe --tags)
docker tag myapp gordon.mydomain.com/myapp:$VERSION
docker tag myapp gordon.mydomain.com/myapp:latest
docker push gordon.mydomain.com/myapp:$VERSION
docker push gordon.mydomain.com/myapp:latest
```

### Semantic Versioning

Use semantic versions for clear recovery targets:

```
v2.1.0  ← Current (broken)
v2.0.0  ← Recovery target
v1.9.0  ← Older stable
```

### Git SHA Tags

Tag with commit SHA for precise recovery:

```bash
# Deploy
SHA=$(git rev-parse --short HEAD)
docker push gordon.mydomain.com/myapp:$SHA
```

## Verifying Recovery

After re-deploying the previous version:

```bash
# Check the app's effective vs observed state
gordon apps status blog --remote prod

# Check application responds
curl -I https://app.mydomain.com

# Check logs
gordon apps logs blog --remote prod
```

## Best Practices

1. **Always tag versions** - Don't rely solely on `latest`
2. **Keep N previous versions** - Maintain recovery options
3. **Test before deploy** - Reduce need for rollbacks
4. **Document known-good versions** - Track stable releases

## Related

- [Deployment Overview](./index.md)
- [GitHub Actions](./github-actions.md)
- [Apps CLI](../cli/apps.md)