About

serverless lambda in golang with aws dynamodb local

Installation

make: choco install make | apt-get install make
file-watcher: pip install https://github.com/joh/when-changed/archive/master.zip
aws-sam: aws-sam: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-install.html
docker: choco install docker-desktop | sudo apt-get install docker-ce docker-ce-cli containerd.io
dynamodb-admin: npm install dynamodb-admin -g

Development

Full list of commands are listed in Makefile If you are on windows, you need to have git bash cli installed to run the commands1

start aws-sam development server

make aws-sam

watch files in ./src directory and recompile whenever they change

Open another terminal
make watch

note

Only file changes in the src directory is detected.
Also note that if you change the sam-template.yml file, you will have to restart the aws-sam development server too

start local dynamodb server

Open another terminal
make db

Note: Connecting aws-sam to dynamodb local

Need to ensure that aws-sam and dynamodb local run on the same docker network

sam local start-api --docker-network local-network

# docker-compose.yml for amazon/dynamodb-local
networks:
  backend:
    name: local-network

services:
  dynamodb:
    image: amazon/dynamodb-local
    ports:
      - 1234:8000
    networks: 
      - backend

Need to configure the aws sdk client to point to the local dynamodb endpoint, e.g.

var config = aws.NewConfig().WithEndpoint("http://localhost:1234").
var Client = dynamodb.New(..., config)

If running docker on windows, need to speicfy the endpoint as http://host.docker.internal:1234 instead of http://localhost:1234. This is due to the fact that the host has a changing IP address.

Inspect dynamodb with dynamodb-admin

After make db, open the browser, and go to http://localhost:8001

stop dynamodb local

make stop-db

Starting with an empty project template

npm install -g serverless
serverless create --template aws-go-mod --path my-folder

Then replace the serverless.yml with the sam-template.yml serverless framework does not yet fully support golang development, e.g. no sls offline dev server
Regardless, the generated template is helpful

eugbyte/sls-go-mod