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Setting up borg backup (optional)

The playbook can install and configure borgbackup with borgmatic for you. BorgBackup is a deduplicating backup program with optional compression and encryption. That means your daily incremental backups can be stored in a fraction of the space and is safe whether you store it at home or on a cloud service.

You will need a remote server where borg will store the backups. There are hosted, borg compatible solutions available, such as BorgBase.

The backup will run based on matrix_backup_borg_schedule var (systemd timer calendar), default: 4am every day.

By default, if you're using the integrated Postgres database server (as opposed to an external Postgres server), Borg backups will also include dumps of your Postgres database. An alternative solution for backing up the Postgres database is postgres backup. If you decide to go with another solution, you can disable Postgres-backup support for Borg using the matrix_backup_borg_postgresql_enabled variable.

Prerequisites

Create a new SSH key:

ssh-keygen -t ed25519 -N '' -f matrix-borg-backup -C matrix

This can be done on any machine and you don't need to place the key in the .ssh folder. It will be added to the Ansible config later.

Add the public part of this SSH key (the matrix-borg-backup.pub file) to your borg provider/server:

If you plan to use a hosted solution, follow their instructions. If you have your own server, copy the key over:

# example to append the new PUBKEY contents, where:
# PUBKEY is path to the public key,
# USER is a ssh user on a provider / server
# HOST is a ssh host of a provider / server
cat PUBKEY | ssh USER@HOST 'dd of=.ssh/authorized_keys oflag=append conv=notrunc'

Adjusting the playbook configuration

Minimal working configuration (inventory/host_vars/matrix.DOMAIN/vars.yml) to enable borg backup:

matrix_backup_borg_enabled: true
matrix_backup_borg_location_repositories:
 - ssh://USER@HOST/./REPO
matrix_backup_borg_storage_encryption_passphrase: "PASSPHRASE"
matrix_backup_borg_ssh_key_private: |
  -----BEGIN OPENSSH PRIVATE KEY-----
  TG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNlY3RldHVyIGFkaXBpc2NpbmcgZW
  xpdCwgc2VkIGRvIGVpdXNtb2QgdGVtcG9yIGluY2lkaWR1bnQgdXQgbGFib3JlIGV0IGRv
  bG9yZSBtYWduYSBhbGlxdWEuIFV0IGVuaW0gYWQgbWluaW0gdmVuaWFtLCBxdWlzIG5vc3
  RydWQgZXhlcmNpdGF0aW9uIHVsbGFtY28gbGFib3JpcyBuaXNpIHV0IGFsaXF1aXAgZXgg
  ZWEgY29tbW9kbyBjb25zZXF1YXQuIA==
  -----END OPENSSH PRIVATE KEY-----

where:

USER - SSH user of a provider/server
HOST - SSH host of a provider/server
REPO - borg repository name, it will be initialized on backup start, eg: matrix, regarding Syntax see Remote repositories
PASSPHRASE - passphrase used for encrypting backups, you may generate it with pwgen -s 64 1 or use any password manager
PRIVATE KEY - the content of the private part of the SSH key you created before. The whole key (all of its belonging lines) under matrix_backup_borg_ssh_key_private needs to be indented with 2 spaces

To backup without encryption, add matrix_backup_borg_encryption: 'none' to your vars. This will also enable the matrix_backup_borg_unknown_unencrypted_repo_access_is_ok variable.

matrix_backup_borg_location_source_directories defines the list of directories to back up: it's set to {{ matrix_base_data_path }} by default, which is the base directory for every service's data, such as Synapse, Postgres and the bridges. You might want to exclude certain directories or file patterns from the backup using the matrix_backup_borg_location_exclude_patterns variable.

Check the roles/custom/matrix-backup-borg/defaults/main.yml file for the full list of available options.

Installing

After configuring the playbook, run the installation command again:

ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start

Manually start a backup

For testing your setup it can be helpful to not wait until 4am. If you want to run the backup immediately, log onto the server and run systemctl start matrix-backup-borg. This will not return until the backup is done, so possibly a long time. Consider using tmux if your SSH connection is unstable.

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