A pgbarman docker image with Prometheus metrics
After properly configured this image runs a cron with the cron command every minute. That "executes WAL archiving operations concurrently on a server basis, and this also enforces retention policies on those servers that have:
retention_policynot empty and valid;retention_policy_modeset to auto.
The cron command ensures that WAL streaming is started for those servers that have requested it, by transparently executing the receive-wal command."
The image currently is focused on streaming replication so no rsync streaming or now.
$ docker run -v /path/to/db/configs:/etc/barman.d/ -v /path/to/backupdata/:/var/lib/barman/ decsis/pg-barman
For an full overview of using this image with a server check the example configuration for in the docker-compose.yml. If you run this compose file you will obtain two PostgresSQL servers and a Barman scheduled to make full backups every hour for server1 and every 6 hours to server2. Also a Prometheus server will be available to gather metrics from the exporter included in the image.
docker-compose up
After that Barman will complain in the log:
barman_1 | 2017-03-17 11:54:02,239 [192] barman.server ERROR: replication slot 'barman' doesn't exist. Please execute 'barman receive-wal --create-slot postgreslab1'
barman_1 | 2017-03-17 11:54:02,256 [193] barman.wal_archiver INFO: Synchronous WAL streaming for barman_receive_wal: False
barman_1 | 2017-03-17 11:54:02,257 [193] barman.server ERROR: replication slot 'barman' doesn't exist. Please execute 'barman receive-wal --create-slot postgreslab2'
Just run:
docker exec -u barman -it dockerbarman_barman_1 barman receive-wal --create-slot postgreslab1
docker exec -u barman -it dockerbarman_barman_1 barman receive-wal --create-slot postgreslab2
Give it a minute or so to settle up and then execute the following to make PostgreSQL servers switch to another transaction log file and allows barman to be ready to do backups:
docker exec -u barman -it dockerbarman_barman_1 barman switch-xlog --force all
Prepare the recovery ssh connexion from barman to rec_pg:
docker exec -u barman -it dockerbarman_barman_1 ssh-keygen -t rsa && cat ~/.ssh/id_rsa.pub
Allow the barman's public key just displayed on rec_pg:
docker exec -u root -it dockerbarman_rec_pg_1 sh
# echo the key to ~/.ssh/authorized_key
# then chhmod 0600 ~/.ssh/authorized_key
Finally execute the backups:
docker exec -u barman -it dockerbarman_barman_1 barman backup all
At any point you can view the status at http://localhost:8000
IMPORTANT: Take this just as a quick overview of the image funcionality. Please do read the barman manual and the PostgreSQL documentation to fully understand what is going on.
All ENV variables that starts with BARMAN_ will be converted read and converted to the correct format needed for barman.conf file. Example BARMAN_MINIMUM_REDUNDANCY=1 will be inserted as minimum_redundancy=1. Full list of options at pgbarman's manual.
Alternatively it is possible to mount a volume file in $BARMAN_BARMAN_HOME/.barman.conf that will override the base config file.
For server configurations provide a file per server in /etc/barman.d/ as stated in the barman manual.
Additionaly you can pass a extra configuration in these files for scheduling backups:
#:backup_cron = 0 10 * * *
#:backup_recovery_ssh_cmd = "ssh root@rec_pg"
backup_cron
The image runs a every minute script that maintains (insert, update and delete) the crontab gathering this property from the available *.conf files. The resulting crontab for the previous example:
MAILTO=""
BARMAN_LOG_FILE=/var/log/barman.log
BARMAN_PRE_BACKUP_SCRIPT=/opt/barman/scripts/pre_backup.sh
BARMAN_POST_BACKUP_SCRIPT=/opt/barman/scripts/post_backup.sh
BARMAN_BARMAN_HOME=/var/lib/barman
BARMAN_CONFIGURATION_FILES_DIRECTORY=/etc/barman.d
* * * * * barman cron
* * * * * /opt/barman/scripts/backup_scheduler.sh
0 10 * * * barman backup postgreslab3
backup_recovery_ssh_cmd
If this property is present after each backup of the corresponding database a recovery attempt will be performed and its duration registered as a Prometheus metric.
Currently this only works with the companion image https://hub.docker.com/r/decsis/postgres-ssh/ .
Important: Please notice that this additional properties are prefixed by #: to avoid barman complaining about an unknown property. The : is there to make clear this is not just a comment.
The image ships with a Prometheus exporter in the form of a Python script. After the container starts the metrics should be available at http://localhost:8000.
It will generate the following metrics:
- barman_status Status as given by barman check command (0 is OK everything else is bad)
- barman_last_backup_size_bytes Last backup size in bytes
- barman_expected_redundancy Number of expected backups as defined in config minimum_redundancy
- barman_database_size_bytes Database size in bytes
- barman_backup_duration_seconds Backup duration in seconds
- barman_recovery_duration_seconds Recovery duration in seconds
- barman_recovery_status Recovery status per database
- barman_backup_window_seconds Backup window covered by all existing backups
- barman_last_backup_age_seconds Last backup age
- barman_current_redundancy Number of existing backups
A sample scrape config is available in example/prometheus_config.yml