A super simple service to convert an alpha numeric Ordnance Survey grid reference to easting / northing or easting / northing to a grid reference.

View online at https://gridref.longwayaround.org.uk.

To start a local web server for development you can use ring:

lein ring server-headless

Build and run a Docker image based on the Dockerfile.

docker build -t gridref-web .
docker run -it --rm --memory-swap 250m --memory 250m --env PORT=8181 -p 8181:8181 --name gridref-web gridref-web

Specifying the same value for --memory-swap and --memory effectively limits the container to that much memory without swap which mimics the fly.io free-tier.

The above sets the PORT environment variable which is used in the Dockerfile to determine which port the embedded app server listens on; the -p option exposes the container port to localhost for testing.

Initial setup and deployment under a fly.dev domain:

flyctl auth login
fly launch

Choices made via fly launch:

# ? Choose an app name (leave blank to generate one): gridref-web
# ? Choose a region for deployment: London, United Kingdom (lhr)
# Created app 'gridref-web' in organization 'personal'
# ? Would you like to set up a Postgresql database now? No
# ? Would you like to set up an Upstash Redis database now? No
# ? Create .dockerignore from 3 .gitignore files? Yes
# ? Would you like to deploy now? No

Check the generated fly.toml (no changes needed) so we can deploy which will make the app available under a fly.dev sub-domain.

flyctl deploy

Setup a sub-domain and cert:

1. Create a CNAME to pointing at the fly.dev sub-domain of the app
2. Request a certificate via the flyctl:

flyctl certs create gridref.longwayaround.org.uk

App is available at https://gridref.longwayaround.org.uk/.