AWS Lambda Connecting to Local Postgres in Docker

Question

I'm attempting to connect to a local Postgres server running as a docker container from my Lambda function.

I'm using the sam local invoke call to do so.

For some reason, it seems that outgoing connection from SAM's docker container for the function is disabled.

I'm getting this error message:

"errorMessage": "(psycopg2.OperationalError) could not connect to server: Connection refused\n\tIs the server running on host \"localhost\" (127.0.0.1) and accepting\n\tTCP/IP connections on port 5432?\ncould not connect to server: Cannot assign requested address\n\tIs the server running on host \"localhost\" (::1) and accepting\n\tTCP/IP connections on port 5432?\n\n(Background on this error at: http://sqlalche.me/e/e3q8)",

Is there a way to enable a Lambda function call to a local docker database?

I have no issues running the connection code outside the Lambda function as standard Python code - so I'm sure my database is up, my code works, etc.

Answer 1

Try running the command with —docker-network TEXT per the AWS SAM CLI documentation.

I had a similar issue attempting to run sam local start-api with a local Docker Postgres database and was getting connection refused errors. I ran sam local start-api —docker-network host and it resolved the issue.

This is a good post which helped me to understand more about Docker networks.

Hope this helps you and any others looking at this.