Thumbnailr

This is a sample AWS serverless api for creating thumbnails from photos. It's built with Golang and AWS SAM and its intented usage is to serve as a sandbox or an educational resource.

Getting Started

You need to follow the AWS instructions to install the required software and setup your AWS account.

You also need to install mage for building the lambdas and delve for locally debugging them.

Note that I've developed this on a Mac OS and I'm using bash for a few, very simple, convenient shell scripts. Some of these scripts have a dependency to jq and some others to httpie.

Build

The following snippets assume that you've opened a terminal and cd'ed to the the host_lambda directory.

Build all Lambdas

mage -d ./mage build

which builds up to max_concur_builds lambdas concurrently. The value of max_concur_builds can be set in the ./mage/conf.ini file.

Build a Single Lambda

TN_HANDLER=<LambdaResourceName> mage -d ./mage build

where LambdaResourceName is the resource name in the template.yaml file (e.g. CheckCreationFunction)

Run Locally

For the lambdas triggered by the API Gateway, you need to run the following:

sam local start-api

then get the access token:

http POST "http://127.0.0.1:3000/token?grant_type=password&username=test&password=test"

and then invoke the lambda (e.g.):

http POST "http://127.0.0.1:3000/request_creation?width=100&length=100&photoID=buddha.jpg&format=PNG" authorization:"Bearer <ACCESS_TOKEN>"

The thumbnail creation lambda is triggered by an SNS event. To run this lambda you need to:

1. edit the create_message.json
2. run gen_create_event.sh that generates the create_message.json
3. run sam local invoke as shown below

sam local invoke CreateFunction -e create_event.json

Make sure the photstore S3 bucket has some photos. You can find a few in the photostore bucket.

Debug Locally

The following snippets assume that you've opened a terminal and cd'ed to the the host_lambda directory.

For step-through debugging you need to build delve for the lambda OS and Architecture. This is done with:

./build_delve.sh

Also you need to setup you IDE to run remote go debugging on port 5986.

These are one-off steps which you don't need to repeat.

Then you need to build with env var TN_DEBUG=true. For all lambdas:

TN_DEBUG=true mage -d ./mage build

For a single lambda:

TN_DEBUG=true TN_HANDLER=<LambdaResourceName> mage -d ./mage build

where LambdaResourceName is the resource name in the template.yaml file (e.g. CheckCreationFunction)

Finally you need to follow the steps in the Run Locally section. Each sam command needs the following additions:

-d 5986 --debugger-path ./delve --debug-args "-delveAPI=2"

Deploy

Make sure you've built all handlers with debugging off (default option). With a terminal cd'ed to the the host_lambda directory run the following:

./deploy.sh

This script assumes an S3 Bucket named sam-deployment-<AWS_ACCOUNT_ID> where the packaged lambdas are uploaded.

Note that:

1. API GW HTTPS Url is printed. You need that Url to perform calls at the production environment.
2. ALB is not created (SAM does not provide this option yet). One needs to create it manually and wire it with the lambdas ending in '-alb'.

Run

The steps are identical to those of Run Locally but the local HTTP url needs to be replaced with the output HTTPS URL of the deployment script.