Serverless Offline Golang Development Setup

A preliminary setup & skeleton to kickstart with local AWS Lambda development in Go.

It's a mixture of Serverless and SAM Local. Using the former as deployment framework due to its wider range of features, bigger community and its language/provider agnostic nature. And the latter only for offline Lambda + API Gateway simulation using a docker container.

Requirements

• Working Golang environment, preferably with dep
• Working Node environment to install dependencies
• Working Docker machine to invoke lambdas locally

Installation & usage

# Install npm dependencies
npm install -g serverless aws-sam-local

# Clone the skeleton
git clone https://github.com/sepehr/serverless-offline-go.git golambda

# Compile the sample lambdas
cd golambda/
make

# Invoke the "apigw" sample lambda locally at localhost:3000
sam local start-api

# Invoke the "Vanilla" sample lambda locally using a custom event payload file
sam local invoke "Vanilla" -e path/to/event.json
# Or using an event payload from the stdin
 echo '{"message": "Hey, are you there?" }' | sam local invoke "Vanilla"

# Deploy to AWS
# Requires authenticated aws-cli setup in place
sls deploy -s dev

Making changes

• Renaming lambdas requires you to update the names in Makefile, serverless.yml and template.yml.
• Updating APIGW endpoints requires you to update both serverless.yml and template.yml (if you want it offline).

Additional Notes

• Included serverless.yml definition is originated from the official aws-go-dep template provided by the serverless framework with just a minimal update to add a APIGW endpoint.
• One of the template sample lambdas has been replaced by a more useful one that can work with APIGW.
• Sample lambdas have been organized into cmd/ directory as per common practice.

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