borgmatic/docs/how-to/make-per-application-backups.md

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How to make per-application backups	key parent order 🔀 Make per-application backups How-to guides 1

Multiple backup configurations

You may find yourself wanting to create different backup policies for different applications on your system or even for different backup repositories. For instance, you might want one backup configuration for your database data directory and a different configuration for your user home directories. Or one backup configuration for your local backups with a different configuration for your remote repository.

The way to accomplish that is pretty simple: Create multiple separate configuration files and place each one in a /etc/borgmatic.d/ directory. For instance, for applications:

sudo mkdir /etc/borgmatic.d
sudo generate-borgmatic-config --destination /etc/borgmatic.d/app1.yaml
sudo generate-borgmatic-config --destination /etc/borgmatic.d/app2.yaml

Or, for repositories:

sudo mkdir /etc/borgmatic.d
sudo generate-borgmatic-config --destination /etc/borgmatic.d/repo1.yaml
sudo generate-borgmatic-config --destination /etc/borgmatic.d/repo2.yaml

When you set up multiple configuration files like this, borgmatic will run each one in turn from a single borgmatic invocation. This includes, by default, the traditional /etc/borgmatic/config.yaml as well.

Each configuration file is interpreted independently, as if you ran borgmatic for each configuration file one at a time. In other words, borgmatic does not perform any merging of configuration files by default. If you'd like borgmatic to merge your configuration files, for instance to avoid duplication of settings, see below about configuration includes.

Additionally, the ~/.config/borgmatic.d/ directory works the same way as /etc/borgmatic.d.

If you need even more customizability, you can specify alternate configuration paths on the command-line with borgmatic's --config flag. (See borgmatic --help for more information.) For instance, if you want to schedule your various borgmatic backups to run at different times, you'll need multiple entries in your scheduling software of choice, each entry using borgmatic's --config flag instead of relying on /etc/borgmatic.d.

Archive naming

If you've got multiple borgmatic configuration files, you might want to create archives with different naming schemes for each one. This is especially handy if each configuration file is backing up to the same Borg repository but you still want to be able to distinguish backup archives for one application from another.

borgmatic supports this use case with an archive_name_format option. The idea is that you define a string format containing a number of Borg placeholders, and borgmatic uses that format to name any new archive it creates. For instance:

storage:
    ...
    archive_name_format: home-directories-{now}

This means that when borgmatic creates an archive, its name will start with the string home-directories- and end with a timestamp for its creation time. If archive_name_format is unspecified, the default is {hostname}-{now:%Y-%m-%dT%H:%M:%S.%f}, meaning your system hostname plus a timestamp in a particular format.

New in version 1.7.11 borgmatic uses the archive_name_format option to automatically limit which archives get used for actions operating on multiple archives. This prevents, for instance, duplicate archives from showing up in rlist or info results—even if the same repository appears in multiple borgmatic configuration files. To take advantage of this feature, simply use a different archive_name_format in each configuration file.

Under the hood, borgmatic accomplishes this by substituting globs for certain ephemeral data placeholders in your archive_name_format—and using the result to filter archives when running supported actions.

For instance, let's say that you have this in your configuration:

storage:
    ...
    archive_name_format: {hostname}-user-data-{now}

borgmatic considers {now} an emphemeral data placeholder that will probably change per archive, while {hostname} won't. So it turns the example value into {hostname}-user-data-* and applies it to filter down the set of archives used for actions like rlist, info, prune, check, etc.

The end result is that when borgmatic runs the actions for a particular application-specific configuration file, it only operates on the archives created for that application. Of course, this doesn't apply to actions like compact that operate on an entire repository.

If this behavior isn't quite smart enough for your needs, you can use the match_archives option to override the pattern that borgmatic uses for filtering archives. For example:

storage:
    ...
    archive_name_format: {hostname}-user-data-{now}
    match_archives: sh:myhost-user-data-*        

For Borg 1.x, use a shell pattern for the match_archives value and see the Borg patterns documentation for more information. For Borg 2.x, see the match archives documentation.

Some borgmatic command-line actions also have a --match-archives flag that overrides both the auto-matching behavior and the match_archives configuration option.

Prior to 1.7.11 The way to limit the archives used for the prune action was a prefix option in the retention section for matching against the start of archive names. And the option for limiting the archives used for the check action was a separate prefix in the consistency section. Both of these options are deprecated in favor of the auto-matching behavior (or match_archives/--match-archives) in newer versions of borgmatic.

Configuration includes

Once you have multiple different configuration files, you might want to share common configuration options across these files with having to copy and paste them. To achieve this, you can put fragments of common configuration options into a file, and then include or inline that file into one or more borgmatic configuration files.

Let's say that you want to include common retention configuration across all of your configuration files. You could do that in each configuration file with the following:

location:
   ...

retention:
    !include /etc/borgmatic/common_retention.yaml

And then the contents of common_retention.yaml could be:

keep_hourly: 24
keep_daily: 7

To prevent borgmatic from trying to load these configuration fragments by themselves and complaining that they are not valid configuration files, you should put them in a directory other than /etc/borgmatic.d/. (A subdirectory is fine.)

When a configuration include is a relative path, borgmatic loads it from either the current working directory or from the directory containing the file doing the including.

Note that this form of include must be a YAML value rather than a key. For example, this will not work:

location:
   ...

# Don't do this. It won't work!
!include /etc/borgmatic/common_retention.yaml

But if you do want to merge in a YAML key and its values, keep reading!

Include merging

If you need to get even fancier and merge in common configuration options, you can perform a YAML merge of included configuration using the YAML << key. For instance, here's an example of a main configuration file that pulls in retention and consistency options via a single include:

<<: !include /etc/borgmatic/common.yaml

location:
   ...

This is what common.yaml might look like:

retention:
    keep_hourly: 24
    keep_daily: 7

consistency:
    checks:
        - name: repository

Once this include gets merged in, the resulting configuration would have all of the location options from the original configuration file and the retention and consistency options from the include.

Prior to borgmatic version 1.6.0, when there's a section collision between the local file and the merged include, the local file's section takes precedence. So if the retention section appears in both the local file and the include file, the included retention is ignored in favor of the local retention. But see below about deep merge in version 1.6.0+.

Note that this << include merging syntax is only for merging in mappings (configuration options and their values). But if you'd like to include a single value directly, please see the section above about standard includes.

Additionally, there is a limitation preventing multiple << include merges per section. So for instance, that means you can do one << merge at the global level, another << within each configuration section, etc. (This is a YAML limitation.)

Deep merge

New in version 1.6.0 borgmatic performs a deep merge of merged include files, meaning that values are merged at all levels in the two configuration files. This allows you to include common configuration—up to full borgmatic configuration files—while overriding only the parts you want to customize.

For instance, here's an example of a main configuration file that pulls in two retention options via an include and then overrides one of them locally:

<<: !include /etc/borgmatic/common.yaml

location:
   ...

retention:
    keep_daily: 5

This is what common.yaml might look like:

retention:
    keep_hourly: 24
    keep_daily: 7

Once this include gets merged in, the resulting configuration would have a keep_hourly value of 24 and an overridden keep_daily value of 5.

When there's an option collision between the local file and the merged include, the local file's option takes precedence.

New in version 1.6.1 Colliding list values are appended together.

Shallow merge

Even though deep merging is generally pretty handy for included files, sometimes you want specific sections in the local file to take precedence over included sections—without any merging occuring for them.

New in version 1.7.12 That's where the !retain tag comes in. Whenever you're merging an included file into your configuration file, you can optionally add the !retain tag to particular local mappings or sequences to retain the local values and ignore included values.

For instance, start with this configuration file containing the !retain tag on the retention mapping:

<<: !include /etc/borgmatic/common.yaml

location:
   repositories:
     - repo.borg

retention: !retain
    keep_daily: 5

And common.yaml like this:

location:
   repositories:
     - common.borg

retention:
    keep_hourly: 24
    keep_daily: 7

Once this include gets merged in, the resulting configuration will have a keep_daily value of 5 and nothing else in the retention section. That's because the !retain tag says to retain the local version of retention and ignore any values coming in from the include. But because the repositories sequence doesn't have a !retain tag, that sequence still gets merged together to contain both common.borg and repo.borg.

The !retain tag can only be placed on mapping and sequence nodes, and it goes right after the name of the option (and its colon) on the same line. The effects of !retain are recursive, meaning that if you place a !retain tag on a top-level mapping, even deeply nested values within it will not be merged.

Additionally, the !retain tag only works in a configuration file that also performs a merge include with <<: !include. It doesn't make sense within, for instance, an included configuration file itself (unless it in turn performs its own merge include). That's because !retain only applies to the file doing the include; it doesn't work in reverse or propagate through includes.

Debugging includes

New in version 1.7.12 If you'd like to see what the loaded configuration looks like after includes get merged in, run validate-borgmatic-config on your configuration file:

sudo validate-borgmatic-config --show

You'll need to specify your configuration file with --config if it's not in a default location.

This will output the merged configuration as borgmatic sees it, which can be helpful for understanding how your includes work in practice.

Configuration overrides

In more complex multi-application setups, you may want to override particular borgmatic configuration file options at the time you run borgmatic. For instance, you could reuse a common configuration file for multiple applications, but then set the repository for each application at runtime. Or you might want to try a variant of an option for testing purposes without actually touching your configuration file.

Whatever the reason, you can override borgmatic configuration options at the command-line via the --override flag. Here's an example:

borgmatic create --override location.remote_path=/usr/local/bin/borg1

What this does is load your configuration files, and for each one, disregard the configured value for the remote_path option in the location section, and use the value of /usr/local/bin/borg1 instead.

You can even override multiple values at once. For instance:

borgmatic create --override section.option1=value1 section.option2=value2

This will accomplish the same thing:

borgmatic create --override section.option1=value1 --override section.option2=value2

Note that each value is parsed as an actual YAML string, so you can even set list values by using brackets. For instance:

borgmatic create --override location.repositories=[test1.borg,test2.borg]

Or even a single list element:

borgmatic create --override location.repositories=[/root/test.borg]

If your override value contains special YAML characters like colons, then you'll need quotes for it to parse correctly:

borgmatic create --override location.repositories="['user@server:test.borg']"

There is not currently a way to override a single element of a list without replacing the whole list.

Note that if you override an option of the list type (like location.repositories), you do need to use the [ ] list syntax. See the configuration reference for which options are list types. (YAML list values look like - this with an indentation and a leading dash.)

Be sure to quote your overrides if they contain spaces or other characters that your shell may interpret.

An alternate to command-line overrides is passing in your values via environment variables.

Constant interpolation

New in version 1.7.10 Another tool is borgmatic's support for defining custom constants. This is similar to the variable interpolation feature for command hooks, but the constants feature lets you substitute your own custom values into anywhere in the entire configuration file. (Constants don't work across includes or separate configuration files though.)

Here's an example usage:

constants:
    user: foo
    archive_prefix: bar

location:
    source_directories:
        - /home/{user}/.config
        - /home/{user}/.ssh
    ...

storage:
    archive_name_format: '{archive_prefix}-{now}'

In this example, when borgmatic runs, all instances of {user} get replaced with foo and all instances of {archive-prefix} get replaced with bar-. (And in this particular example, {now} doesn't get replaced with anything, but gets passed directly to Borg.) After substitution, the logical result looks something like this:

location:
    source_directories:
        - /home/foo/.config
        - /home/foo/.ssh
    ...

storage:
    archive_name_format: 'bar-{now}'

An alternate to constants is passing in your values via environment variables.