Automated Fly.io Postgres Database Backups

An example showing how to use a GitHub action to automate backups of a Fly.io Postgres database as well as then uploading the backups to S3 (or another storage provider of your choosing).

Quick Start

Clone this repo and add your environment variables as secrets to your GitHub action.

• Control the cron frequency in the backup.yml file
  

Recognition

This example is based on the following tutorial by advantch. However, there were certain steps which were unclear to me—as someone with relatively little python or bash knowledge.

I also find the Fly naming conventions confusing—particularly between the switching of hyphens and underscores in app names. This made the tutorial harder to follow and I thought it was worth sharing for others.

A Simple Explanation

We proxy our Postgres app to port 5432 and then perform usual pg_dump commands.

Setting up your environment variables

Add the following environment variables to your GitHub action secrets.

For illustration purposes, assume my main fly app is called my-example-app and my attached Postgres fly app is called my-example-app-db.

💡 How to find some of these values is explained further down.

Fly.io specific variables

	Example	Explanation
PG_PASSWORD
PG_USER	my_example_app	Note the underscores
PG_DATABASE	my_example_app	Note the underscores
APP_NAME	my-example-app	main fly app name
PROXY_APP_NAME	my-example-app-db	attached fly Postgres app name

S3 specific variables

	Example	Explanation
S3_ACCESS_KEY
S3_SECRET_ACCESS_KEY
S3_BUCKET	my-database-backups
AWS_REGION	eu-west-1

Slack specific variables

For alerting a channel if the workflow fails. See here for more info.

	Example	Explanation
SLACK_CHANNEL_ID
SLACK_BOT_TOKEN

### How to retrieve certain environment values

Ensure that you are logged into your fly account:

flyctl auth login

Retrieving Your App Names

flyctl list apps

Retrieving your Postgres Users

fly postgres users list -a my-example-app-db

Retrieving the Postgres specific values

For your app name, do not use the Postgres app name; instead, it needs to be the app to which the PostGres app is attached. If you omit the -a flag it will use the app specified in your fly.toml file—which is usually what we want anyway.

flyctl ssh console -a my-example-app

echo $DATABASE_URL

You can also see all variables with

printenv

Again, assuming my main fly app is called my-example-app and my postgres fly app is called my-example-app-db.

Your DATABASE_URL should look something like: postgres://my_example_app:[email protected]:5432/my_example_app?sslmode=disable

💡 postgres://{username}:{password}@{hostname}:{port}/{database}?options

Learn more here

What is confusing is when to use hyphens and when to use underscores.

It helps to remember that "Fly Postgres is a regular app". So we need to differentiate between the naming of the Fly app hosting the Postgres database to that of the actual database itself.

For Local Testing:

Ensure Postgres is setup correctly (especially the path)

sudo mkdir -p /etc/paths.d && echo /Applications/Postgres.app/Contents/Versions/latest/bin | sudo tee /etc/paths.d/postgresapp

Create and activate a virtual environment.

Run the following lines of code in your terminal:

$ python3 -m venv .venv
$ source .venv/bin/activate
$ python3 -m pip install -r requirements.txt

The connection to DB often hangs when testing locally--so you may need to kill it.

lsof -i tcp:5432
kill xxx