Bootstack Charmers Next Duplicity

  • By BootStack Charmers - NEXT
juju deploy bootstack-charmers-next-duplicity
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You will need Juju 2.9 to be able to run this command. Learn how to upgrade to Juju 2.9.
Channel Version Revision Published Runs on
latest/stable 1 1 18 Mar 2021
Ubuntu 20.04 Ubuntu 18.04 Ubuntu 16.04


20.04 18.04 16.04


Duplicity offers encrypted bandwidth-efficient backup Read more

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Duplicity Charm


The Duplicity charm provides functionality for both manual and automatic backups for a deployed application. As the name suggests, it utilizes the Duplicity tool and acts as an easy-to-use-and-configure interface for operators to set up backups.

After relating the Duplicity to another charm, you can backup a directory to either the local unit, a remote host, or even an AWS S3 bucket. All it takes is a bit of configuration and remote destination preparation.

The following backends are currently supported:

  • File (local)
  • S3
  • SCP
  • Rsync


Simple deployment

This will get duplicity deployed on whatever deployed charm you want. Here, we see it being related to the ubuntu charm.

juju deploy ubuntu
juju deploy duplicity
juju add-relation duplicity ubuntu

However, we will need to fill out various other, required configs, depending on the backend type selected.

Local file backups

This will backup a selected directory to the local unit.

juju config duplicity \
    backend=file \
SCP/Rsync/SFTP Backups

Using the backends scp, rsync, and sftp require, at minimum, the following options to be set.

juju config duplicity \
    backend=scp \
    known_host_key=', ssh-rsa AAABBBCCC' \
    private_ssh_key="$(base64 my_priv_id)"

Alternatively, you can use remote_password=password instead of the private_ssh_key option if you prefer password authentication.

S3 Backups

The following will backup to S3 buckets. This configuration requires an IAM account access and secret key to be passed into the config.

juju config duplicity \
    backend=s3 \ \
    aws_access_key_id=my_aws_key \

To encrypt your backups, you can use symmetric encryption using a passed in password or encrypt the backup with a GPG key. Alternative to these methods, you can ignore encryption entirely.

# Symmetric password encryption
juju config duplicity encryption_passphrase=my_passphrase

# Asymmetric GPG encryption
juju config duplicity gpg_public_key=MY_GPG_KEY

# Disable encryption (not recommended)
juju config duplicity disable_encryption=True
Setting Periodic Backups

The big draw of this charm is being able to periodically backup a directory. By default, the charm will only backup manually, i.e. through the do-backup action. To enable periodic backups, set backup_frequency to any of the following:

  • hourly
  • daily
  • weekly
  • monthly
  • any valid cron schedule string
Adding NRPE Checks for alerting

Adding NRPE checks allows for alerting when a periodic backup fails to complete.

juju deploy nrpe
juju add-relation nrpe ubuntu       # required on host 
juju add-relation nrpe duplicity

Known Limitations and Future Features

This charm is currently still under development. The only supported Duplicity action right now is full backups (through both an action and periodic backups). The following is the list of future Duplicity functionality:

  • incremental backups
  • restoring backups
  • verifying backups
  • listing backed-up files
  • cleaning up backed files
  • additional supported backends

Upstream and Bugs

The repository can be found here.

Please report bugs or feature requests on Launchpad.