WAL-G: Perform weekly full backup and retain 4 full backups

In this commit, we have made important changes to the backup and retention strategy. We have transitioned from using the 'wal-g delete before FIND_FULL' command to 'wal-g delete retain'. This change was made to ensure a more robust and predictable backup retention policy. With 'wal-g delete retain', we explicitly specify the number of full backups to retain, which provides better control over the backup history.

Furthermore, we have introduced a new configuration option, 'WALG_DELTA_MAX_STEPS', which is set to '6'. This option determines the maximum number of delta backups that can be retained between full backups. By limiting the number of data backups, we can optimize storage utilization and ensure efficient backup management.

Additionally, we have added logging to capture the results of both backup creation and deletion. This logging will help us monitor the success and effectiveness of the backup and retention process, allowing us to quickly identify any issues or anomalies.

vars/main.yml

@@ -412,6 +412,7 @@ wal_g_json:  # config https://github.com/wal-g/wal-g#configuration
   - { option: "AWS_SECRET_ACCESS_KEY", value: "{{ AWS_SECRET_ACCESS_KEY | default('') }}" }  # define values or pass via --extra-vars
   - { option: "WALG_S3_PREFIX", value: "{{ WALG_S3_PREFIX | default('') }}" } # define values or pass via --extra-vars
   - { option: "WALG_COMPRESSION_METHOD", value: "brotli" }  # or "lz4", "lzma", "zstd"
+  - { option: "WALG_DELTA_MAX_STEPS", value: "6" }  # determines how many delta backups can be between full backups
   - { option: "PGDATA", value: "{{ postgresql_data_dir }}" }
   - { option: "PGHOST", value: "{{ postgresql_unix_socket_dir }}" }
   - { option: "PGPORT", value: "{{ postgresql_port }}" }
@@ -431,16 +432,16 @@ wal_g_cron_jobs:
     day: "*"
     month: "*"
     weekday: "*"
-    job: "[ $(curl -s -o /dev/null -w '%{http_code}' http://{{ inventory_hostname }}:{{ patroni_restapi_port }}) = '200' ] && wal-g backup-push {{ postgresql_data_dir }}"
-  - name: "WAL-G: Delete old backups" # older than 30 days (by default). Change according to your company's backup retention policy.
+    job: "[ $(curl -s -o /dev/null -w '%{http_code}' http://{{ inventory_hostname }}:{{ patroni_restapi_port }}) = '200' ] && wal-g backup-push {{ postgresql_data_dir }} > {{ postgresql_log_dir }}/walg_backup.log 2>&1"
+  - name: "WAL-G: Delete old backups" # retain 4 full backups (adjust according to your company's backup retention policy)
     user: "postgres"
     file: /etc/cron.d/walg
     minute: "30"
     hour: "6"
     day: "*"
     month: "*"
     weekday: "*"
-    job: "[ $(curl -s -o /dev/null -w '%{http_code}' http://{{ inventory_hostname }}:{{ patroni_restapi_port }}) = '200' ] && wal-g delete before FIND_FULL $(date -d '-30 days' '+%FT%TZ') --confirm"
+    job: "[ $(curl -s -o /dev/null -w '%{http_code}' http://{{ inventory_hostname }}:{{ patroni_restapi_port }}) = '200' ] && wal-g delete retain FULL 4 --confirm > {{ postgresql_log_dir }}/walg_delete.log 2>&1"
 
 # pgBackRest
 pgbackrest_install: false  # or 'true'