Add Custom AWS YAML Tags in VS Code

Visual Studio Code was showing an IntelliSense error when adding !Ref and !GetAtt tags in my serverless.yml.

I was trying to reference the StoresTable resource using the CloudFormation pseudo functions !Ref and !GetAtt:

unknown tag <!Ref>

unknown tag <!GetAtt>

serverless.yml

provider:
  name: aws
  runtime: nodejs12.x

  iamRoleStatements:
    - Effect: Allow
      Action: dynamodb:scan
      Resource: !GetAtt StoresTable.Arn

functions:
  get-stores:
    handler: functions/get-stores.handler
    events:
      - http:
          path: /stores
          method: get
    environment:
      stores_table: !Ref StoresTable

resources:
  Resources:
    StoresTable:
      Type: AWS::DynamoDB::Table
      Properties:
        BillingMode: PAY_PER_REQUEST
        AttributeDefinitions:
          - AttributeName: name
            AttributeType: S
        KeySchema:
          - AttributeName: name
            KeyType: HASH

  Outputs:
    StoresTableName:
      Value: !Ref StoresTable

Add yaml.customTags in VSCode settings.json

The fix was to add the yaml.customTags property in my Visual Studio Code settings.json, with an array of custom tags I wanted to support.

VSCode - settings.json

{
  // ... other settings
  "yaml.customTags": ["!Ref", "!GetAtt"]
}