litestream-docker-example

Litestream & Docker Example

This repository provides an example of running a Go application in the same container as Litestream by using the built-in subprocess execution. This allows developers to release their SQLite-based application and provide replication in a single container.

Usage

Prerequisites

To test this locally, you'll need to have an S3-compatible store to connect to. Please see the Litestream Guides to get set up on your preferred object store.

You'll also need to update the replica URL in etc/litestream.yml in this repository to your appropriate object store.

You'll also need to set your object store credentials in your shell environment:

export LITESTREAM_ACCESS_KEY_ID=XXX
export LITESTREAM_SECRET_ACCESS_KEY=XXX

Building & running the container

You can build the application with the following command:

docker build -t myapp .

Once the image is built, you can run it with the following command. Be sure to change the REPLICA_URL variable to point to your bucket.

docker run \
  -p 8080:8080 \
  -v ${PWD}:/data \
  -e REPLICA_URL=s3://YOURBUCKETNAME/db \
  -e LITESTREAM_ACCESS_KEY_ID \
  -e LITESTREAM_SECRET_ACCESS_KEY \
  myapp

Let's break down the options one-by-one:

• -p 8080:8080—maps the container's port 8080 to the host machine's port 8080 so you can access the application's web server.

• -v ${PWD}:/data—mounts a volume from your current directory on the host to the /data directory inside the container.

• -e REPLICA_URL=...—sets an environment variable for your replica. This is used by the startup script to restore the database from a replica if it doesn't exist and it is used in the Litestream configuration file.

• -e LITESTREAM_ACCESS_KEY_ID & -e LITESTREAM_SECRET_ACCESS_KEY—passes through your current environment variables for your S3 credentials to the container. You can also use AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY instead.

Testing it out

In another window, you can run:

curl localhost:8080

and you should see:

This server has been visited 1 times.

Each time you run cURL, it will increment that value by one.

Recovering your database

You can simulate a catastrophic disaster by stopping your container and then deleting your database:

rm -rf db db-shm db-wal .db-litestream

When you restart the container again, it should print:

No database found, restoring from replica if exists

and then begin restoring from your replica. The visit counter on your app should continue where it left off.