matthewrankin / go-sls-crudl

An example Serverless framework project using Golang to build a simple API Gateway -> Lambda -> DynamoDB set of methods

go-sls-crudl

This project riffs off of the Dynamo DB Golang samples and the Serverless Framework Go example to create an example of how to build a simple API Gateway -> Lambda -> DynamoDB set of methods. This is a fork of the repository referenced in Pete Johnson's article "A DynamoDB-Backed CRUDL example using Golang".

Code Organization

Note that, instead of using the create_table.go to set up the initial table like the AWS code example does, the resource building mechanism that Serverless provides is used. Individual code is organized as follows:

• functions/get/main.go - GET method for reading a specific item
• functions/list-by-year/main.go - GET method for listing all or a subset of items
• functions/post/main.go - POST method for creating a new item
• functions/put/main.go - PUT method for updating an existing item
• functions/delete/main.go - DELETE method for deleting a specific item
• img/* - Images of DynamoDB tables to make this Readme easier to follow
• helpers/dao/moviedao.go - DAO wrapper around the DynamoDB calls
• helpers/parse/parse.go - Helper functions related to parsing, such as Unslugify to convert a slug into a space separated string.
• helpers/resp/resp.go - Helper functions to simplify providing an APIGatewayProxyResponse.
• data/XXX.json - Set of sample data files for POST and PUT actions
• Makefile - Used for testing, building, and deploying the functions.
• serverless.yml - Defines the initial table, function defs, and API Gateway events

Compared to nerdguru/go-sls-crudl layout, I've moved each main package into its own folder, so that the main() func isn't being redeclared in multiple files in the same directory.

Set Up

If you are a Serverless Framework rookie, follow the installation instructions here. If you are a grizzled vet, be sure that you have v1.26 or later as that's the version that introduces Golang support. You'll also need to install Go.

When both of those tasks are done, and after you've cloned the repository, you can run make to see the available commands to build, check, clean, and deploy.

When done deploying using make deploy, you can find the new DynamoDB table in the AWS Console, which should initially look like this:

and your <base URL> will be of the format 'https://XXXXXXXXXX.execute-api.us-east-1.amazonaws.com/dev/movies' where XXXXXXXXXX will be some random string generated by AWS.

The development cycle would then be:

• Make changes to the .go files
• Run make deploy to compile and deploy the binaries
• Use curl to then interrogate the API as described below

Using

Once deployed and substituting your <base URL> the following CURL commands can be used to interact with the resulting API, whose results can be confirmed in the DynamoDB console

POST

curl -X POST https:<base URL> -d @data/post1.json

Which should result in the DynamoDB table looking like this:

Rinse/repeat for other data files to yeild:

GET Specific Item

Using the year and title (replacing spaces wiht '-' or '+'), you can now obtain an item as follows (prettified output):

curl https://<base URL>/2013/Hunger-Games-Catching-Fire
{
  "year": 2013,
  "title": "Hunger Games Catching Fire",
  "info": {
    "plot": "Katniss Everdeen and Peeta Mellark become targets of the
             Capitol after their victory in the 74th Hunger Games sparks
             a rebellion in the Districts of Panem.",
    "rating": 7.6
  }
}

GET a List of Items

You can list items by year as follows (prettified output):

curl https://<base URL>/2013
[
  {
    "year": 2013,
    "title": "Hunger Games Catching Fire",
    "info": {
      "plot": "",
      "rating": 0
    }
  },
  {
    "year": 2013,
    "title": "Turn It Down Or Else",
    "info": {
      "plot": "",
      "rating": 0
    }
  }
]

DELETE Specific Item

Using the same year and title specifiers, you can delete as follows:

curl -X DELETE https://<base URL>/2013/Hunger-Games-Catching-Fire

Which should result in the DynamoDB table looking like this:

UPDATE Specific Item

You can update as follows:

curl -X PUT https:<base URL> -d @data/put3.json

Which should result in the DynamoDB table looking like this: