You can easily debug your serverless application with the Serverless Framework and the Serverless Offline Plugin when you only have one, but how do you handle the case when you have multiple API Gateways/services?
Should I run serverless offline for every service, with a different port configured in each .yml?
and hardcode that port in the environment variables so I can access that port if process.env.offline is true?
If you want to run two or more Serverless API Gateways at the same time locally you can easily do it with --port parameter.
Basically, open two command line windows and in the first window, go to your first service directory and run:
sls offline start --port 3001
in the other window, go to your second service and run:
sls offline start --port 3002
This way you you will have two services listening on two ports (in this examples http://localhost:3001 and http://localhost:3002).
There is one catch (at the moment) if you also use serverless-dynamodb-local plugin:
If you don't use DynamoDB plugin then you are okay and can stop reading now :)
DynamoDB plugin is using the same --port parameter and that causes java.net.BindException: Address already in use
See this issue: https://github.com/99xt/serverless-dynamodb-local/issues/135
The workaround for this is to keep serverless-offline-local plugin enabled in only one service (if you have two or more).
Example,
In my-service-1 you keep all dynamodb config in serverless.yaml file and start this service with default port: sls offline start --migrate true. In the next service, let's call it my-service-2 you remove serverless-dynamodb-local from plugins in serverless.yaml (there is no need for any other changes) and then you can start the service with: sls offline start --port 3001.
First service will start DynamoDB and the second one will be able to use it.