How to add S3 trigger event on AWS Lambda function using Serverless framework?

Question

I want to add trigger event on a Lambda function on an already existing bucket and for that I am using below configuration:

 events:
      - s3:
          bucket: serverlesstest
          event: s3:ObjectCreated:*
          rules:
            - prefix: uploads/
            - suffix: .pdf

where bucket serverlesstest is already existing on S3.

This configurations is throwing the error:

An error occurred while provisioning your stack: S3BucketServerlesstest - serverlesstest already exists.

How can I resolve this error using Serverless Framework?

yabaiwebyasan · Accepted Answer · 2018-02-27 10:12:28Z

13

It’s not currently possible in the core framework because of CloudFormation behavior. maybe.

But you can use this plugin.

https://github.com/matt-filion/serverless-external-s3-event

After installing serverless-plugin-existing-s3 by npm install serverless-plugin-existing-s3.

And add plugins to serverless.yml

plugins:
  serverless-plugin-existing-s3

Give your deploy permission to access the bucket.

provider:
  name: aws
  runtime: nodejs4.3
  iamRoleStatements:
    ...
    -  Effect: "Allow"
       Action:
         - "s3:PutBucketNotification"
       Resource:
         Fn::Join:
           - ""
       - - "arn:aws:s3:::BUCKET_NAME or *"

And use existingS3 event, it is not just s3.

functions:
  someFunction:
    handler: index.handler
    events:
      - existingS3:
          bucket: BUCKET_NAME
          events:
            - s3:ObjectCreated:*
          rules:
            - prefix: images/
            - suffix: .jpg

After sls deploy command, You can attach event by using sls s3deploy command.

Feature Proposal

it will be added someday in the future.

https://github.com/serverless/serverless/issues/4241

answered Feb 27, 2018 at 10:12

yabaiwebyasan

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1 Comment

Marius Mihail Over a year ago

NOTE: This property was added in version 1.47.0. Older versions don't support this feature. (source: serverless.com/framework/docs/providers/aws/events/…)

Community · Accepted Answer · 2020-06-20 09:12:55Z

13

This is possible as of serverless version v1.47.0, by adding the existing: true flag to your event configuration: https://serverless.com/framework/docs/providers/aws/events/s3/

example from the source:

functions:
  users:
    handler: users.handler
    events:
      - s3:
          bucket: legacy-photos
          event: s3:ObjectCreated:*
          rules:
            - prefix: uploads/
            - suffix: .jpg
          existing: true # <- this makes it work with existing objects

The source provides the following caveats:

IMPORTANT: You can only attach 1 existing S3 bucket per function.

NOTE: Using the existing config will add an additional Lambda function and IAM Role to your stack. The Lambda function backs-up the Custom S3 Resource which is used to support existing S3 buckets.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Oct 10, 2019 at 20:30

Ulad Kasach

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4 Comments

garryp Over a year ago

It does nothing. I'm on Serverless 1.5.0 and it completely ignore this property. I literally copy-pasted the code from the docs with a few renames. Completely broken feature.

DemonGyro Over a year ago

I'm having the same problem on 1.58.0 (latest at the time of writing). I had to manually create the event trigger. I really wished this would work...

sorjef Over a year ago

@DemonGyro @garryp Note that this functionality creates an additional lambda function yourservicenameandstage-custom-resource-existing-s3. If this additional lambda function is not created try checking the indentation of parameters in - s3 tag. Note that parameters have 4 spaces instead of 2 spaces after the parent tag. I had a similar problem and this fixed it for me so hope it helps.

DemonGyro Over a year ago

Thanks for the tip. I have decided to handle things a little differently, so I don't need this functionality anymore, but I will definitely keep the spacing in mind later if I try this again.

Zanon · Accepted Answer · 2017-06-29 11:29:04Z

5

Unfortunately, you can't specify an existing S3 bucket to trigger the Lambda function because the Serverless Framework* can't change existing infrastructure using Cloud Formation. This configuration requires that you create a new bucket.

You can read more in the following issues that were open on GitHub:

^{* I would try to configure this trigger using AWS Console or the SDK instead of the Serverelss Framework.}

answered Jun 29, 2017 at 11:29

Zanon

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Comments

Trent Bartlem · Accepted Answer · 2017-06-29 07:15:19Z

3

If the bucket was created using Serverless elsewhere in the stack, then you could use - s3: Bucket: { Ref: serverlesstest } Otherwise you'll have to construct the name or ARN yourself.

answered Jun 29, 2017 at 7:15

Trent Bartlem

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1 Comment

Ronit kadwane Over a year ago

Now I can able to upload function successfully but trigger event still missing on Lambda function.

Yevhenii · Accepted Answer · 2020-06-11 15:23:20Z

3

serverless.yml seems to be very sensitive to spaces. For me this advice was helpful.

If config looks like this

functions:
  hello:
    handler: handler.main
    events:
      - s3: 
        bucket: codepipeline-us-east-1-213458767560
        event: s3:ObjectCreated:*
        rules:
          - prefix: test/MyAppBuild

you need to add 2 more spaces to the indent of bucket, event & rules:

functions:
  hello:
    handler: handler.main
    events:
      - s3: 
          bucket: codepipeline-us-east-1-213458767560
          event: s3:ObjectCreated:*
          rules:
            - prefix: test/MyAppBuild

answered Jun 11, 2020 at 15:23

Yevhenii

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