A utility to backup or transfer a Docker Swarm.

• Why should I use this?
• Usage
  • Backup a Swarm
  • Restore from Backup
  • Copy from Swarm to Swarm
• Registry Authentication
• Flags
• Known Issues / TODO
• License

Why should I use this?

Existing Swarm backup strategies require root filesystem access, are stored in encrypted proprietary formats, and if you've fallen prey to a Swarm-corrupting bug the backup will retain that bug like an infection.

Lifevest creates plain JSON backups that are reconstructed from scratch upon restore. This means that your services, configurations, and secrets can live outside of Docker's Raft configurations, are immune to Swarm corruption bugs, and can serve as a single source of truth for Docker upgrades or automated processes.

Usage

Install this utility by running:

npm install -g @originalfunko/docker-lifevest

A quick reference is available with docker-lifevest --help.

A few common usages are below:

Backup a Swarm

To take a backup of a Swarm, run:

docker-lifevest --source <docker swarm IP or DNS>

A folder called backup-<datetime> will be created in the current directory. The directory looks like this:

backup-<datetime>
├ services - <JSON dumps of services>
├ configs - <JSON dumps of configs>
└ secrets - <JSON dumps of secrets>

To change the output directory, add --destination <new folder path>

Secrets are not encrypted in this backup, so please treat the backup carefully.

It is recommended to encrypt them:

tar cvz - backup-20XX-01-01T00-00-00-000Z/ |\
openssl enc \
  -kfile myFileContainingAPassword.txt \
  -aes-256-cbc \
  -out backup-20XX-01-01T00-00-00-000Z.tar.gz.enc

To decrypt this backup later:

openssl enc \
  -d \
  -kfile myFileContainingAPassword.txt \
  -aes-256-cbc \
  -in backup-20XX-01-01T00-00-00-000Z.tar.gz.enc |\
tar xz

Restore from Backup

To restore from a backup folder, run:

docker-lifevest --input folder --source <folder path> --output swarm --destination <docker swarm IP or DNS>

If your services pull from a private registry, you must create a JSON file containing authentication for that registry at registry-credentials.json. See Registry Authentication.

Existing items will not be replaced; it is recommended that you restore to a clean Swarm by doing something like the following:

systemctl stop docker
rm -rf /var/lib/docker/swarm
systemctl start docker
docker swarm init

Copy from Swarm to Swarm

To copy from one Swarm to another without an intermediate backup, run docker-lifevest --source <source IP or DNS> --output swarm --destination <dest IP or DNS>

Registry Authentication

If your services use authentication when pulling their images, you will need to create a JSON file containing those credentials in order to restore those services.

The JSON file must follow Docker's API format. Only services with images matching the serveraddress field in that file will use the authentication credentials, so images from other registries will not be affected.

When using --output swarm, add this file with the --registry-credentials <file path> flag.

Flags

Known Issues / TODO

Currently only services, configs, and secrets are backed up. More object types may be added in the future.

TLS support for Docker access.

Per-service registry authentication

License

This software is licensed under the Mozilla Public License 2.0. The full text of the license is included with this software.