This docker image can be used as a backup "sidecar" container to a
TimescaleDB container. It makes periodic
backups using WAL-E (https://github.com/wal-e/wal-e) as well as WAL
backups. WAL-E will not backup configuration files so they need to be
stored separately. If they are stored where the
WAL-E sidecar container can reach them, they can be restored during the
WAL-E restore process using the environment variable PGCONF_BACKUP_DIR.
The TimescaleDB and the WAL-E containers need to share PGDATA and
PGWAL disk volumes. Before starting the TimescaleDB instance,
the TimescaleDB container needs to create a
$PGDATA/wale_init_lockfile (our official Docker release
supports this). When the WAL-E sidecar container
removes that file, it is safe for TimescaleDB to start.
Typical modifications to postgresql.conf are
archive_command='/usr/bin/wget wale_container_hostname:5000/wal-push/%f -O -'
wal_level=archive
archive_mode=on
archive_timeout=600
checkpoint_timeout=700
The WAL-E container is configured using environment variables.
First, the startup operation is controlled by
the START_MODE variable where the options are CONTINOUS_BACKUP, BACKUP_PUSH, or RESTORE.
| MODE | Operation |
|---|---|
| BACKUP_PUSH | Pushes a base backup before starting to accept archive commands |
| CONTINOUS_BACKUP | Starts up and accepts archive commands |
| RESTORE | Fetches a backup, creates a restore.conf, and optionally restores configuration files |
The backup and restore operation can be further configured through the following variables.
| Variable | Use | Default |
|---|---|---|
| WALE_RESTORE_LABEL | label of backup to pull when restoring | LATEST |
| WALE_SIDECAR_HOSTNAME | hostname where the sidecar can be reached | localhost |
| WALE_LISTEN_PORT | port | 5000 |
| CRON_TIMING | Cron string for periodic backups | "0 0 * * *" (24h) |
| RECOVERY_ADDITION | line to add to recovery.conf, typically timestamp for PIT recovery | - |
| PGCONF_BACKUP_DIR | directory path holding configuration files to restore after data dir restore | - |
| PGDATA | path to mounted TimescaleDB/PostgreSQL data dir | - |
The WAL-E container can be used to run arbitrary WAL-E commands using
the wal-e binary. For example, to list the stored backups
you can run
docker exec <wale_container_name> wal-e backup-list