Postgresql Backup To Amazon S3 On OpenShift Origin

To move forward, you need to backup. Backing up your production data is critical and with Postgresql, you can backup WAL (Write Ahead Log) archives and this post gives you steps to accomplish for backing up postgresql WALs to Amazon S3 on your OpenShift Origin using WAL-E.

WAL-E is a great tool that simplifies backup of postgresql by performing continuous archiving of PostgreSQL WAL files and base backups. Enough blabbering, you can reach out technical docs on how WAL works. I'll just mention series of commands and steps necessary for sending WAL archives to AWS S3 bucket.

On the node containing application with postgresql cartridge, run the following commands:

$ yum install python-pip lzop pv
$ rpm -Uvh ftp://ftp.pbone.net/mirror/ftp5.gwdg.de/pub/opensuse/repositories/home:/p_conrad:/branches/Fedora_19/x86_64/daemontools-0.76-3.1.x86_64.rpm
$ pip install wal-e
$ umask u=rwx,g=rx,o=
$ mkdir -p /etc/wal-e.d/env
$ echo "secret-key-content" > /etc/wal-e.d/env/AWS_SECRET_ACCESS_KEY
$ echo "access-key" > /etc/wal-e.d/env/AWS_ACCESS_KEY_ID
$ echo 's3://backup/production/pgsql' > \
  /etc/wal-e.d/env/WALE_S3_PREFIX
$ chmod -R 765 /etc/wal-e.d/

Then, edit the postgresql configuration file so as to turn on wal archiving. You need to find the right container for your postgresql in /var/lib/openshift (Its quite trivial if you know OpenShift basics).

$ vi YOUR_OO_CONTAINER/postgresql/data/postgresql.conf wal_level = archive # hot_standby in 9.0 is also acceptable
archive_mode = on
archive_command = 'envdir /etc/wal-e.d/env wal-e wal-push %p'
archive_timeout = 60

Finally, you need to ensure that you are taking base backups periodically which can be achieved by utilizing cron cartridge. Clone the repo, add the following file and push to the application.

$ vi .openshift/cron/daily/postgres-backup
#!/bin/bash

if [ $OPENSHIFT_POSTGRESQL_DIR ]; then
        /usr/bin/envdir /etc/wal-e.d/env /bin/wal-e backup-push ${OPENSHIFT_POSTGRESQL_DIR}data
fi

$ git add .openshift/cron/daily/postgres-backup
$ git commit -m "Added pg cron script"
$ git push origin master

Make sure you use the OPENSHIFT_POSTGRESQL_DIR env-var or some other env-var that does not have two forward slashes adjacently since WAL-E hates it.

This should help you keep your data backed up regularly and you can enjoy beers.


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