How to use dynamoDb locally with lambda

Question

I think this is possible? I have a lambda and api gateway defined in a sam template. I use sam-local to start that up. Within my lambda I would like to connect to my local dynamoDB but the lambda keeps timing out. Code looks like:

let AWS = require('aws-sdk')
let dyn= new AWS.DynamoDB({ endpoint: new AWS.Endpoint("http://localhost:8000") })

function handler(event, context, callback) {
  dyn.listTables({Limit: 10}, function(err, data) {
    if (err) {
      console.log("Error", err.code)
    } else {
      console.log("Table names are ", data.TableNames)
    }
  })

  let response = {
    statusCode: 200
  }
  callback(null, response)
}

If this code is run outside of a lambda it works fine

Answer 1

Your DynamoDB is running on the local machine, while the SAM Local is running inside a Docker container.

If you create a Docker container for DynamoDB to run in, and have this in the same Docker network as the SAM Local container, you might have more success.

Answer 2

I'm doing the same thing as you. But I run locally my DynamoDB as a docker image using this command. I run this on mac:

docker run -p 8000:8000 amazon/dynamodb-local

In your code change this:

endpoint: new AWS.Endpoint("http://localhost:8000")

to this:

endpoint: new AWS.Endpoint("http://docker.for.mac.localhost:8000")

Now lambda can connect to port and will not timed out.