Duplicity Cron Runner

What?

This image includes Duplicity ready to make backups of whatever you need, cron-based.

Why?

Because you need to back things up regularly, and Duplicity is one of the best tools available for such a purpose.

How?

Installing every possible Duplicity dependency to support all of its backends inside an Alpine system that is very lightweight by itself, and a little job runner Python script that takes care of converting some environment variables into flexible cron jobs and sending an email report automatically.

Where?

• Source code.
• Prebuilt images in GitHub package registry.

Available images

Each of the built-in flavors is separated into a specific docker image:

• docker-duplicity
• docker-duplicity-s3
• docker-duplicity-docker
• docker-duplicity-docker-s3
• docker-duplicity-postgres
• docker-duplicity-postgres-s3

Check the section bellow to get more info.

Tags

Each of the images mentioned above are tagged with :latest, referring to the latest tagged version in git, and :egde, referring to the latest version in the master branch. Each individual git released version is also tagged (e.g. :0.1.0)

Environment variables available

Apart from the environment variables that Duplicity uses by default, you have others specific for this image.

CRONTAB_{15MIN,HOURLY,DAILY,WEEKLY,MONTHLY}

Define the cron schedule to run jobs under such circumstances.

Possibly non-obvious defaults:

• Daily: 2 AM, from Monday to Saturday
• Weekly: 1 AM, on Sundays
• Monthly: 5 AM, 1st day of month

Hours are expressed in UTC.

If you define any of these variables wrongly, your cron might not work!

You can use online tools such as https://crontab.guru to make it easy.

If you set these values in .env file, don't use quotes:

CRONTAB_15MIN=*/15 * * * *
CRONTAB_HOURLY=0 * * * *
CRONTAB_DAILY=0 2 * * MON-SAT
CRONTAB_WEEKLY=0 1 * * SUN
CRONTAB_MONTHLY=0 5 1 * *

DBS_TO_EXCLUDE

Define a Regular Expression to filter databases that shouldn't be included in the DB dump.

You can use this to avoid getting permission errors when running a backup against a server where you don't control all the databases.

For example, if you don't want to include the databases named DB1 and DB2 you can use:

DBS_TO_EXCLUDE="^(DB1|DB2)$"

DST

Where to store the backup.

Example: ftps://[email protected]/some_dir

EMAIL_FROM

Email report sender.

EMAIL_SUBJECT

Subject of the email report. You can use these placeholders:

• {periodicity} will be one of these:
  • 15min
  • hourly
  • daily
  • weekly
  • monthly
• {result} will be:
  • OK if all worked fine.
  • ERROR if any job failed.
• {hostname} will be the container's host name, including the domainname (a.k.a. FQDN).

This variable is optional; the default is Backup report: {hostname} - {periodicity} - {result}

EMAIL_TO

Email report recipient.

JOB_*_WHAT

Define a command that needs to be executed.

Check the Dockerfile to see built-in jobs.

JOB_*_WHEN

Define when to execute the command you defined in the previous section. If you need several values, you can separate them with spaces (example: daily monthly).

Prebuilt flavors provide built-in jobs. You can disable those jobs by setting corresponding JOB_*_WHEN to value never.

OPTIONS

String to let you define options for duplicity.

OPTIONS_EXTRA

String that some prebuilt flavors use to add custom options required for that flavor. You should never need to use this variable.

SMTP_HOST

Host used to send the email report.

SMTP_PORT

Port used to send the email report.

SMTP_USER

If your mail server requires authentication, specify the user account to log in.

SMTP_PASS

If your mail server requires authentication, specify the password for the SMTP_USER.

SMTP_TLS

Force the email client to connect to the server using SLL/TLS. Note that the client will utilize STARTTLS, regardless of this variable, if the server offers STARTTLS.

SRC

What to back up.

Example: file:///mnt/my_files

By default, SRC is set to /mnt/backup/src/ inside the container. Simply mount any external directory as a volume to /mnt/backup/src/. If you wish to include multiple directories, mount them as subdirectories of /mnt/backup/src/, like...

volumes:
  - /path/to/data/to/backup1:/mnt/backup/src/foldername1:ro
  - /path/to/data/to/backup2:/mnt/backup/src/foldername2:ro

TZ

Define a valid timezone (i.e. Europe/Madrid or America/New_York) to make log hours match your local reality.

This is achieved directly by bundling the tzdata package. Refer to its docs for more info.

Set a custom hostname!

Duplicity checks the host name that it backs up and aborts the process if it detects a mismatch by default.

Docker uses volatile host names, so you better add --hostname (and maybe also --domainname) when running this container to make profit of this feature, or add --allow-source-mismatch to OPTIONS environment variable. Otherwise, you will get errors like:

Fatal Error: Backup source host has changed.
Current hostname: 414e54ed20fb
Previous hostname: 6529bba0969c

Aborting because you may have accidentally tried to backup two different
data sets to the same remote location, or using the same archive directory.
If this is not a mistake, use the --allow-source-mismatch switch to avoid
seeing this message

Pre and post scripts

Add jobs through environment variable pairs. The order will be followed.

Using Duplicity

Refer to Duplicity man page, or execute:

docker run -it --rm ghcr.io/tecnativa/docker-duplicity duplicity --help

Shortcuts

You can use these bundled binaries to work faster:

• dup: Executes duplicity prefixed with the options defined in $OPTIONS and $OPTIONS_EXTRA (see above).
• backup: Executes an immediate backup with default options.
• restore: Restores immediately with default options. Most likely, you will need to use it with --force.
• /etc/periodic/daily/jobrunner: execute immediately all jobs scheduled for daily backups. Change daily for other periodicity if you want to run those instead.

Testing your configuration

If you want to test how do your daily jobs work, just run:

docker exec -it your_backup_container /etc/periodic/daily/jobrunner

Replace daily by any other periodicity to test it too.

Prebuilt flavors

Sometimes you need more than just copying a file here, pasting it there. That's why we supply some special flavours of this image.

Normal (docker-duplicity)

This includes just the most basic packages to boot the cron and use Duplicity with any backend. All other images are built on top of this one, so downloading several flavours won't repeat the abse layers (disk-friendly!).

It's preconfigured to backup daily:

# Incremental backup of all files
JOB_300_WHEN=daily

PostgreSQL (docker-duplicity-postgres)

If you want to back up a PostgreSQL server, make sure you run this image in a fashion similar to this docker-compose.yaml definition:

services:
  db:
    image: postgres:9.6-alpine
    environment:
      POSTGRES_PASSWORD: mypass
      POSTGRES_USER: myuser
      POSTGRES_DB: mydb
  backup:
    image: ghcr.io/tecnativa/docker-duplicity-postgres
    hostname: my.postgres.backup
    environment:
      # Postgres connection
      PGHOST: db # This is the default
      PGPASSWORD: mypass
      PGUSER: myuser

      # Additional configurations for Duplicity
      AWS_ACCESS_KEY_ID: example amazon s3 access key
      AWS_SECRET_ACCESS_KEY: example amazon s3 secret key
      DST: boto3+s3://mybucket/myfolder
      EMAIL_FROM: [email protected]
      EMAIL_TO: [email protected]
      OPTIONS: --s3-european-buckets --s3-use-new-style
      PASSPHRASE: example backkup encryption secret

It will make dumps automatically:

# Makes postgres dumps for all databases except to templates and "postgres".
# They are uploaded by JOB_300_WHEN
JOB_200_WHEN=daily weekly

Docker (docker-duplicity-docker)

Imagine you need to run some command in another container to generate a backup file before actually backing it up in a remote place.

If this is your case, you can use this version, which includes a prepackaged Docker client.

See this docker-compose.yaml example, where we back up a Gitlab server using its crappy official image:

services:
  gitlab:
    image: gitlab/gitlab-ce
    hostname: gitlab
    domainname: example.com
    environment:
      GITLAB_OMNIBUS_CONFIG: |
        # Your Gitlab configuration here
    ports:
      - "22:22"
      - "80:80"
      - "443:443"
    volumes:
      - config:/etc/gitlab:z
      - data:/var/opt/gitlab:z
      - logs:/var/log/gitlab:z
  backup:
    image: ghcr.io/tecnativa/docker-duplicity-docker
    hostname: backup
    domainname: gitlab.example.com
    privileged: true # To speak with host's docker socket
    volumes:
      - config:/mnt/backup/src/config
      - data:/mnt/backup/src/data
      - /var/run/docker.sock:/var/run/docker.sock:ro
    environment:
      # Generate Gitlab backup before uploading it
      JOB_200_WHAT: docker exec projectname_gitlab_1 gitlab-rake gitlab:backup:create
      JOB_200_WHEN: daily weekly

      # Additional configurations for Duplicity
      AWS_ACCESS_KEY_ID: example amazon s3 access key
      AWS_SECRET_ACCESS_KEY: example amazon s3 secret key
      DST: boto3+s3://mybucket/myfolder
      EMAIL_FROM: [email protected]
      EMAIL_TO: [email protected]
      OPTIONS: --s3-european-buckets --s3-use-new-style
      PASSPHRASE: example backup encryption secret

Amazon S3 (*-s3)

Any of the other flavors has a special variant suffixed with -s3. It provides some opinionated defaults to make good use of S3 different storage types and its lifecycle rules and filters, assuming you want to have weekly full backups. You should combine it with lifecycle and expiration rules at your will.

# Full backup of all files
JOB_500_WHEN=weekly

Note, that for DST variable you should use boto3+s3://bucket_name[/prefix] style.

Development

All the dependencies you need to develop this project (apart from Docker itself) are managed with poetry.

To set up your development environment, run:

pip install pipx  # If you don't have pipx installed
pipx install poetry  # Install poetry itself
poetry install  # Install the python dependencies and setup the development environment

Testing

To run the tests locally, add --prebuild to autobuild the image before testing:

poetry run pytest --prebuild

By default, the image that the tests use (and optionally prebuild) is named test:docker-duplicity. If you prefer, you can build it separately before testing, and remove the --prebuild flag, to run the tests with that image you built:

docker image build -t test:docker-duplicity .
poetry run pytest

If you want to use a different image, pass the --image command line argument with the name you want:

# To build it automatically
poetry run pytest --prebuild --image my_custom_image

# To prebuild it separately
docker image build -t my_custom_image .
poetry run pytest --image my_custom_image

Managing packages

The poetry project configuration (in the pyproject.toml file) includes a section which contains the duplicity dependencies themselves. This allows us to manage those more easily and avoid future conflicts. Those are then exported into a requirements.txt file in this repo, which is the one that is used inside the container.

So, if you need to add a new duplicity dependency to be used inside the container, the correct process would be:

1. Add the dependency to the poetry project with:

   poetry add --optional MY_NEW_PACKAGE
   

   Note that it should be marked as an optional dependency, as it will not be used in general development outside the container.

   The new optional dependency should then be added to the duplicity list in the [tool.poetry.extras] section of pyproject.toml

   [tool.poetry.extras]
   duplicity = ["b2", "b2sdk", "boto", "boto3", "gdata", "jottalib", "paramiko", "pexpect", "PyDrive", "pyrax", "python", "requests", "duplicity", "dropbox", "python", "mediafire", "MY_NEW_PACKAGE"]
   

2. Export the new poetry-resolved list of packages to the requirements.txt file:

   poetry export -E duplicity -o requirements.txt`