SQS Ref in serverless.yml

Serverless Framework
1

Hi,

I’m trying to use serverless to deploy a service which reads a JSON payload on an http endpoint and then passes it to an SQS queue. Here’s my serverless.yml:

provider:
  name: aws
  runtime: nodejs6.10
  environment:
    sqs_url: !Ref MessagesQueue

functions:
  process:
    handler: handler.handler
    events:
      - http: get handler

resources:
  Resources:
    MessagesQueue:
      Type: AWS::SQS::Queue

This gives me an error saying: unknown tag !<!Ref>

Basically, I’m trying to set the environment variable sqs_url to the newly created SQS queue’s url. Is this possible?

2

You can’t (yet) use the YAML CFN functions in Serverless - it’s all converted to JSON under the hood.

If you replace it with a straight “Ref:” object, it should work fine.

3

Hi,

Do you have a sample serverless.yml which does that?

4

Changing the first part of your snippet will fix the error you’re reporting:

provider:
  name: aws
  runtime: nodejs6.10
  environment:
    sqs_url:
      Ref: MessagesQueue
3 Likes
5

Awesome that worked! One more question:

Can I also limit the iamRoleStatements to this Queue, Right now I have this:

iamRoleStatements:
    - Effect: Allow
      Action:
        - sqs:*
      Resource: arn:aws:sqs:*:*:*

I tried changing that to the following but that doesn’t work.

iamRoleStatements:
    - Effect: Allow
      Action:
        - sqs:*
      Resource:
        Ref: MessageQueue
6

Yes, but the IAM Resource requires the Arn instead of the Url.
So use the following:

  iamRoleStatements:
    - Effect: Allow
      Action:
        - sqs:*
     Resource:
       Fn::GetAtt: [ MessageQueue, Arn ]

Or if you prefer, limit the role to only allow adding messages to the queue like so:

  iamRoleStatements:
    - Effect: Allow
      Action:
        - sqs:SendMessage
     Resource:
       Fn::GetAtt: [ MessageQueue, Arn ]

Hope it helps.

6 Likes
7

Awesome, it works. Thanks a lot!

1 Like
8

Same questions…
Thanks! You rock! :muscle:t6:

9

So I have just hit this snag. However in place of the SQS QueueUrl being return I get [object Object] as the environment variable. Not sure why

1 Like
10

This is why your env variable points to a reference not to a value. Maybe you are running your lambda on your local machine (as me).This is because there is not exist a defined stage in our local machines.
In my case I used this plugin in order to get the value in my environment value.
See this post which use serverless-cloudside-plugin in order to define a stage locally and then, get the real environment variable value.

  environment:
    QUEUE_URL:
      Ref: MyQueue

At the beginning QUEUE_URL had [Object object] string value, after using cloudside plugin I got the real value

1 Like
11

Adding a proper working example for anyone who lands on this page.

CREDIT TO: https://dev.to/piczmar_0/aws-lambda-sqs-events-with-serverless-framework-oj6

service: sqs-triggers-demo

provider:
  name: aws
  runtime: nodejs12.x
  profile: sls
  region: us-west-2
  iamRoleStatements:
    - Effect: "Allow"
      Action:
        - "sqs:SendMessage"
        - "sqs:GetQueueUrl"
      Resource: "arn:aws:sqs:${self:provider.region}:811338114632:MyQueue"
    - Effect: "Allow"
      Action:
        - "sqs:ListQueues"
      Resource: "arn:aws:sqs:${self:provider.region}:811338114632:*"


functions:
  sender:
    handler: sender.handler
    events:
      - http:
          path: v1/sender
          method: post
  receiver:
    handler: receiver.handler
    events:
      - sqs:
          arn:
            Fn::GetAtt:
              - MyQueue
              - Arn

resources:
  Resources:
    MyQueue:
      Type: "AWS::SQS::Queue"
      Properties:
        QueueName: "MyQueue"

CREDIT TO: https://dev.to/piczmar_0/aws-lambda-sqs-events-with-serverless-framework-oj6