Automatically create full backups every 7 days

Question

I have a postgresql database configured with pgbackrest for backups. It retains full backups for 7 days:

[global]
repo1-retention-full-type=time
repo1-retention-full=7

I've set up cron to create a full backup on Sunday with incremental backups each day. This works as expected and removes full backups after the most recent is >7 days old. The actual crontab calls a script that uses the pgbackrest commands, but for simplicity:

0 0 * * 0   root    pgbackrest --type=full backup
0 0 * * 1-6 root    pgbackrest backup

I'm looking to configure pgbackrest up to automatically create full backups every 7 days so I would only need one cron job:

0 0 * * *   root    pgbackrest backup

Is this possible, or will I have to write some bash logic in my script?

Answer 1

My solution was to run a bash script in the crontab that checks the day of week:

#!/usr/bin/env bash

BACKUP_TYPE=$1
if [[ -z $BACKUP_TYPE ]]; then
    DOW=$(date +%u)
    # Do a full backup if it's Sunday 
    if [[ $DOW -eq 7 ]]; then
        BACKUP_TYPE="full"
    else
        BACKUP_TYPE=""
    fi
fi

if [[ -z $BACKUP_TYPE ]]; then
    pgbackrest --stanza=stanza backup
else
    pgbackrest --stanza=stanza --type=$BACKUP_TYPE backup
fi