Backup, Restores, & Snapshots
An important part of running any production db-backed application is making sure your data is backed up and safe, and if the unspeakable happens, it’s straightforward to restore data and get back up and running.
Postgres databases on Fly.io are treated as Fly Apps, which you can read more about in the docs. What that means is backing up data is an exercise in taking snapshots of the Postgres app’s volumes, then restoring the snapshots to a new database server, verifying the restoration, and connecting the application to the restored database.
Finding the database app instance
If you set up your application using fly launch
, the name of your database app might be <app-name>-db
, or you might have given it a name during the initial configuration. To figure that out for sure, run the following from the root of the project:
fly info
App
Name = my-app
Owner = personal
Version = 40
Status = running
Hostname = my-app.fly.dev
The Name
key is the name of your app. In this case, the database app would be my-app-db
. Let’s see if that instance exists by appending the -a
flag with the name of the database application:
fly info -a my-app-db
App
Name = my-app-db
Owner = personal
Version = 40
Status = running
Hostname = my-app-db.fly.dev
If that doesn’t work, then try to find the database instance by running:
fly postgres list
NAME OWNER STATUS LATEST DEPLOY
my-app-db personal running 37m11s ago
and look for the database instance under the NAME
column on the list.
Listing snapshots
Fly.io performs daily storage-based snapshots of each of your provisioned volumes. These snapshots can be used to restore your dataset into a new Postgres application.
Snapshots are volume specific, so you need to identify the volume whose snapshot you want to restore from. You can list your volumes by running the volumes list
command with your Postgres app name.
fly volumes list -a <postgres-app-name>
ID NAME SIZE REGION ATTACHED VM CREATED AT
vol_x915grn008vn70qy pg_data 10GB atl b780ce3d 2 weeks ago
vol_ke628r677pvwmnpy pg_data 10GB atl 359d0e24 2 weeks ago
The number of volumes varies depending on how many database replicas were elected when provisioning the database. One primary database and one replica yields 2 volumes.
Once you have identified which volume to target, you can list its snapshots:
fly volumes snapshots list <volume-id>
ID SIZE CREATED AT
vs_2AjJ4lGqQwDbRfxm 29 MiB 2 hours ago
vs_BAARBQxZKl6JKU04 27 MiB 1 day ago
vs_OPQXXna6kA2Qnhz8 26 MiB 2 days ago
The values under the ID
columns are what will be used to restore a snapshot.
Restoring from a snapshot
To restore a Postgres application from a snapshot, simply specify the --snapshot-id
argument when running the create
command as shown below:
fly postgres create --snapshot-id <snapshot-id>
? App Name: my-app-db-restored
Automatically selected personal organization: Awesome Person
? Select region: [Use arrows to move, type to filter]
? Select region: sjc (San Jose, California (US))
? Specify the initial cluster size: 2
? Select VM size: shared-cpu-1x - 256
Creating postgres cluster my-app-db-restored in organization personal
Postgres cluster my-app-db-restored created
Username: postgres
Password: <redacted>
Hostname: my-app-db-restored.internal
Proxy Port: 5432
PG Port: 5433
Save your credentials in a secure place, you won't be able to see them again!
This provisions and launches a new Fly Postgres database server with the specified snapshot.
Connect the Restored Database
Detach the web application from the current Postgres cluster:
fly postgres detach my-app-db
Then attach it to the new cluster:
fly postgres attach my-app-db-restored
Now your application is pointing at the restored database.