Supported tags and respective Dockerfile links

• latest (latest/Dockerfile)

What is duply?

duply is a frontend for the mighty duplicity magic. duplicity is a python based shell application that makes encrypted incremental backups to remote storages. Different backends like ftp, sftp, imap, s3 and others are supported. See the duplicity manpage for a complete list of backends and features.

duply simplifies running duplicity with cron or on the command line by:

• keeping recurring settings in profiles per backup job
• automated import/export of keys between profile and keyring
• enabling batch operations eg. backup_verify_purge
• executing pre/post scripts
• precondition checking for flawless duplicity operation

Installation

This docker image needs a persistent storage to store its configuration, keys and cache files. The corresponding docker command would be

docker run \
  -it \
  -v /path_to_directory/duply:/root \
  kurthuwig/duply:latest

and the corresponding docker-compose (or fig) file would be

duply:
  image: kurthuwig/duply:latest
  volumes:
   - /path_to_directory/duply:/root

Environment variables

The container uses several environment variables for the creation of the GPG key. If you don't understand what they mean, it is probably a good idea to leave them at their default values.

• KEY_TYPE RSA
• KEY_LENGTH 2048
• SUBKEY_TYPE RSA
• SUBKEY_LENGTH 2048
• NAME_REAL Duply Backup
• NAME_EMAIL duply@localhost
• PASSPHRASE random

Help

If you run the container without any commands, a short usage help will be printed.

Create a GPG key

Duply encrypts the backup using GPG. If you want to use an existing key, copy the .gnupg directory into the volume directory. If you want to create a new key, run the container with the command gen-key. This will create a 2048 bit RSA key unless you change the parameters via the environment variables. By default it will create and print a random passphrase unless you set the environment variable PASSPHRASE. The output will contain two lines like these:

gpg: key EF585BDF marked as ultimately trusted
gpg: Created key with passphrase 'naegheakiochaebu'

Please take a note of the key id and the passphrase as you will need them later.

Create a backup configuration

Duply supports an arbitrary number of independent backup configurations. Usually you only use one configration. To create a configuration named default run the container with the parameters

default create

Then go into the volume directory for /root, enter the hidden subdirectory .duply/default and edit the conf file with a text editor. First you should insert the key id from above into GPG_KEY and the passphrase into GPG_PW. Then change the TARGET to your backup location and credentials. Change the SOURCE to something like /backup.

More information can be found in the duply documentation.

Create a backup of the backup configuration

Create a backup of the .duply and the .gnupg directory on a safe medium, e.g. a USB drive, CD or print it out. If you lose this information - especially the GPG key or passphrase - there is no way to decrypt your backup.

Hint: if you do this after the first duply run, there will be ASCII exports of the GPG keys in the .duply/default directory that are easy to print out.

Create a backup

To backup data, you have to mount it as an additional volume into the duply container. If you have used /backup as the SOURCE in the duply configuration, the corresponding volume statement would be

/path_to_data:/backup:ro

The ro makes the data read-only. Then you can create a backup by running the container with the command

default backup

More information can be found in the duply documentation.

List files in the backup

After the first backup, you can see which files have been backed up by running the container with the command

default list

More information can be found in the duply documentation.

Restore a backup

Just like with creating a backup you need to give an additional volume to the container where you want to restore the data, e.g.

/path_to_restore_directory:/restore

Notice the absence of ro so that duply can write to this location. If you have used /restore as the path of the volume, the restore command is

default restore /restore

If you want to restore just a single file, use this command

default fetch path_of_file /restore

More information can be found in the duply documentation.

Contact

Kurt Huwig (@GMail.com: kurthuwig)