Is it possible to use Ref function on option_settings in AWS? - amazon-web-services

Question

I am using Elastic Beanstalk to deploy a worker tier environment using SQS.
In my .ebextensions I have the following file:
option_settings:
aws:elasticbeanstalk:sqsd:
WorkerQueueURL:
Ref: WorkerQueue
HttpPath: "/sqs/"
InactivityTimeout: 1650
VisibilityTimeout: 1680
MaxRetries: 1
Resources:
WorkerQueue:
Type: AWS::SQS::Queue
Properties:
QueueName: "tpc-clients-aws-queue"
VisibilityTimeout: 1680
However, this fails with the following error:
"option_settings" in one of the configuration files failed validation. More details to follow.
Invalid option value: 'Ref=WorkerQueue' (Namespace: 'aws:elasticbeanstalk:sqsd', OptionName: 'WorkerQueueURL'): Value does not satisfy regex: '^$|^http(s)?://.+$' [Valid non empty URL starting with http(s)]
It seems that the AWSCloudFormation Ref function cannot be used in the option_settings. Can someone confirm if this is the case?
I have seen some code snippets here on StackOverflow using intrinsic functions in the option_settings, such as in the mount-config.config of this answer and also on this question. So, are these examples using an invalid syntax? Or there are some intrinsic functions or specific resources that can be used on the option_settings?
And lastly, if I cannot use the Ref function, how can I go about this?

Answer 1

Yes, you can reference in .ebextentions, but the syntax is a bit strange. It is shown in the docs here.
You can try something along these lines (note the various quotations marks):
option_settings:
aws:elasticbeanstalk:sqsd:
WorkerQueueURL: '`{"Ref" : "WorkerQueue"}`'
HttpPath: "/sqs/"
InactivityTimeout: 1650
VisibilityTimeout: 1680
MaxRetries: 1
Resources:
WorkerQueue:
Type: AWS::SQS::Queue
Properties:
QueueName: "tpc-clients-aws-queue"
VisibilityTimeout: 1680
You can also use ImportValue, if you export the WorkerQueue in outputs.
Update
To check the value obtained, you can set it as an env variable, and inspect in EB console:
option_settings:
aws:elasticbeanstalk:application:environment:
SQS_NAME: '`{"Ref" : "WorkerQueue"}`'

Answer 2

After digging further in this issue I made some discoveries I would like to share with future readers.
Ref can be used on option_settings
As #Marcin answer states, the Ref intrinsic function can be used in the option_settings. The syntax is different though:
'`{"Ref" : "ResourceName"}`'
Using Ref on aws:elasticbeanstalk:application:environment (environment variable)
An use case of the above is to store the queue URL in an environment variable, as follows:
option_settings:
aws:elasticbeanstalk:application:environment:
QUEUE_URL: '`{"Ref" : "WorkerQueue"}`'
This will let your .sh script access the URL of the queue:
Note that if you check the Elastic Beanstalk console (Environment > Config > Software), you won't see the actual value:
Using Ref on aws:elasticbeanstalk:sqsd:WorkerQueueURL
If you try to use the following setting:
option_settings:
aws:elasticbeanstalk:sqsd:
WorkerQueueURL: '`{"Ref" : "WorkerQueue"}`'
HttpPath: "/sqs/"
It will fail:
Invalid option value: '`{"Ref" : "WorkerQueue"}`' (Namespace: 'aws:elasticbeanstalk:sqsd', OptionName: 'WorkerQueueURL'): Value does not satisfy regex: '^$|^http(s)?://.+$' [Valid non empty URL starting with http(s)]
It seems that this configuration option don't accept a reference.
Instead of creating a new queue and assign it to the sqs daemon, you can just update the queue that Elastic Beanstalk creates:
option_settings:
# SQS daemon will use default queue created by EB (AWSEBWorkerQueue)
aws:elasticbeanstalk:sqsd:
HttpPath: "/sqs/"
Resources:
# Update the queue created by EB
AWSEBWorkerQueue:
Type: AWS::SQS::Queue
Properties:
QueueName: "tpc-clients-aws-queue"