Deploying to Railway

The first step is to create a Dockerfile for your project. If you're using a monorepo, place the Dockerfile in apps/indexers.

FROM quay.io/apibara/sink-postgres:0.7.0-x86_64

WORKDIR /app
COPY ./src/* /app

ENTRYPOINT ["/nix/store/rh1g8pb7wfnyr527jfmkkc5lm3sa1f0l-apibara-sink-postgres-0.7.0/bin/apibara-sink-postgres"]

Notice that the base image is build from scratch (not an OS like Ubuntu), so the binary is in a location that depends on the build. For this reason we stick to a specific version and architecture.

When updating the image you also need to update the Docker ENTRYPOINT.

First pull the new version of the image.

docker image pull quay.io/apibara/sink-postgres:0.7.0-x86_64

2352c28bb4a7: Download complete
979824b603fa: Download complete
quay.io/apibara/sink-postgres:0.7.0-x86_64

Then get the entrypoint path by inspecting the image.

docker image inspect quay.io/apibara/sink-postgres:0.7.0-x86_64 | jq '.[].Config.Entrypoint'

[
  "/nix/store/rh1g8pb7wfnyr527jfmkkc5lm3sa1f0l-apibara-sink-postgres-0.7.0/bin/apibara-sink-postgres"
]

Save and push to GitHub.

From the Railway dashboard, create a new service deployment and connect your GitHub repository.

• Change "root directory" to the folder containing your Dockerfile, e.g. /apps/indexers.
• Builder should automatically switch to "Dockerfile". If not, just wait a few seconds until it does.
• Change the "custom start command". Since this option changes the Docker's entrypoint, you will need to pass the full path to the apibara-sink-* executable. For example: /nix/store/rh1g8pb7wfnyr527jfmkkc5lm3sa1f0l-apibara-sink-postgres-0.7.0/bin/apibara-sink-postgres run /app/my-indexer.ts
• Change "restart policy" to "Always".
• Set the AUTH_TOKEN environment variable to your DNA token.
• Set any other relevant environment variable needed by your indexer.
  • For Postgres: POSTGRES_CONNECTION_STRING=${{Postgres.DATABASE_URL}}
  • For Mongo: MONGO_CONNECTION_STRING=${{MongoDB.MONGO_URL}}
• Remember to whitelist environment variables used in your indexer with the --allow-env-from-env option or the ALLOW_ENV_FROM_ENV environment variable. See the environment variables page for more information.
• Once deployed, you should see the indexer starting and running.

The easiest way to persist state between restarts on Railway is by using Redis.

• Deploy a new Redis instance on Railway, and wait for it to become ready.
• Update the following indexer's environment variables:
  • Set PERSIST_TO_REDIS to a reference to Redis' url: ${{Redis.REDIS_URL}}.
  • Set SINK_ID to a unique id for this indexer, e.g. my-indexer.

After redeploying, you will notice that the indexer will store its state (like latest indexed block) in the provided Redis instance.