Serverless – own plugin to attach AWS API Gateway Basic Request Validation

Hey,

I have not had so much time to do as many posts as I wanted since I started my recent project of my own app on AWS using serverless framework. As every good engineer while making my solution I looked at many open source options and serverless seemed to be really good … until I wanted to do something which no one seems to have been doing before ( every one of us know it right ? ) …

So what was that special thing ? Well nothing fancy – just wanted to “attach AWS API Gateway Basic Request Validation” … So I thought … how hard can it be 🙂

As everyone I used “google” to tell me who has done something like that before …. and thats how I visited issue related directly to my problem => https://github.com/serverless/serverless/issues/3464

Had a conversation there with all interested and we all seemed to agree that there is nothing that would work ( at that specific moment 🙂 )

Well by default ( at the moment of writing of this article ) serverless does not support this “out of the box” therefore this has kicked my off to create my own plugin. Since being developer is not my primary focus ( as I do it only as hobbyist 🙂 ) it was a bit of challenge. But it was completed with success. So what was needed to happen to create it ( if you want to skip the story just scroll down 🙂 ) ?

I started by looking into creating a form of “hello world” plugin that would help me to understand how to approach this in best way. Resources for this can be found on the official site of serverless

But I had a feeling this was quite incomplete to create fully functional plugin. So I spend quite a while browsing internet and reading how people created their own plugins from really simple ones – into more advanced which rocks&roll 😉 Here I think the resource that will show you more detailed steps can be found here

With that bits of knowledge I went to the official repo page of plugins and browsed through repositories which were there. This gave me better idea about what I needed to use.

Having all that knowledge I compiled my action plan which basically was:

Create plugin core structure
Add resource to all functions of CloudFormation template based on serverless.yml
Merge template on hook being called before:deploy
Publish for people & get a beer 🙂

This is how I managed to create my plugin available in github https://github.com/RafPe/serverless-reqvalidator-plugin and via npm:

npm install serverless-reqvalidator-plugin

All it does require is extremely simple we start off by creating custom resource in serverless.yml

    xMyRequestValidator:  
      Type: "AWS::ApiGateway::RequestValidator"
      Properties:
        Name: 'my-req-validator'
        RestApiId: 
          Ref: ApiGatewayRestApi
        ValidateRequestBody: true
        ValidateRequestParameters: false

With that one done we add plugin to be enabled

plugins:
    - serverless-reqvalidator-plugin

And then in our functions we specify validator

  debug:
    handler: apis/admin/debug/debug.debug
    timeout: 10
    events:
      - http:
          path: admin/debug
          method: get
          cors: true
          private: true 
          reqValidatorName: 'xMyRequestValidator'

Voilla 😉 And the code in the plugin that does the magic ? You would not believe how much of code that is ….

resources[methodName].Properties.RequestValidatorId = {"Ref": `${event.http.reqValidatorName}`};

And thats it folks 😉 Enjoy and happy coding 🙂

Serverless – own plugin to attach AWS API Gateway Basic Request Validation

rafpe

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