Step9.md

Step 9: Running the back end serverlessly with Lambda

Here's how we can replace the back end with a serverless version:

1. Go to your back end instance and stop it (ctrl+C)
2. Go to the backend-lambda folder instead of the backend-database one
3. Copy the db config file: cp ../backend-database/dbconfig.json dbconfig.json - this is because the serverless version needs the same DB credentials as the backend-database that runs on a server.
4. Run yarn deploy to deploy the serverless app

This will take a little while. Once it's done, you should get an output something like this:

Copy one of the endpoints to your clipboard, without the /units path at the end. For example:

https://jvhws71uuh.execute-api.ap-southeast-2.amazonaws.com/development

Make sure it starts with "https://" and ends with "/development".

Next we need to tell the front end to point to this new back end.

1. Go to the front end shell
2. Navigate to the frontend folder
3. Using nano or vim, open src/config.json and update the host to be the serverless endpoint you copied before
4. Run cat src/config.json to confirm the update worked - you should see the new host printed
5. Run sudo yarn build again to re-build the front end with the new config
6. Run aws s3 cp --recursive build s3://example-bucket again, replacing example-bucket with the name of your bucket, to update the statically hosted site with the new config

If all goes to plan, the static site should now point to the lambda endpoint instead of the server back end - you can verify this by checking requests in the Network tab in the Chrome inspector. Don't shut down the server just yet, as it will help us shut down other things for packing up, but in theory we don't need it anymore as everything is running serverlessly (well, not the database, but at least we don't have to manage the server ourselves).

Next: Cleaning everything up