Specify specific file name trigger function

Hello,
I have several files in my S3 bucket, how do I configure the lambda function to be executed on a specific file update?
For example:

s3-bucket-us-east-1
└── ab73e0f35e
    └── 2016-12-16T10:58:45.123Z_7WdHajGGRbGfX-S0QRUG0Q
        ├── metadata.json
        ├── original.json
        └── updated.json
    └── 2016-12-20T10:58:45.123Z_GPSISqj2ToC-4aGd5YzG5g
        ├── metadata.json
        ├── original.json
        └── updated.json

and my serverless.yaml so far is:

service: update

provider:
  name: aws
  runtime: nodejs4.3
  iamRoleStatements:
    - Effect: Allow
      Action:
        - "s3:*"
      Resource: "*"
  environment:
    S3_INGEST_BUCKET: ${file(./config.js):${self:provider.stage}.S3_TRINTS_BUCKET}
package:
  artifact: handler.zip

functions:
  update:
    handler: handler.update
    events:
      - s3:
          bucket: s3-bucket-${opt:stage, self:provider.stage}-${self:provider.region}
          event: s3:ObjectCreated:Put

I see there is a filter in http://docs.aws.amazon.com/AmazonS3/latest/dev/NotificationHowTo.html, but how do you specify this for example to trigger the function only when the updated.json file has either been added or updated?

Any advice is much appreciated

Amazon only supports prefix/suffix matching with filters, not exact match. The S3 event docs for Serverless include an example of how to configure those.