Events

Spec

topology.yml

name: TOPOLOGY

events:
  EventName:
    producer: String or Array
  producers: Array
    filter: <filter-expression>
    pattern: <JSON Event Pattern>
    function: <function1>
    functions:
      - <function1>
      - <function2>
    mutation: <mutationName>
    state: <state-or-stepfn-fqn>
    channel: <room1>
    rule_name: <static-rule-name>
    doc_only: <bool>

Triggers

tc provides pre-defined triggers

events:
  MyEvent:
    producer: S3/PUT_OBJECT
    filter: '{"key": "foo/bar.png"}'
    function: function1

The following are available triggers for AWS provider

Resource	Trigger	Description
Cognito	PRE_SIGNUP
Cognito	POST_CONFIRMATION
Cognito	PRE_AUTHENTICATION
Cognito	POST_AUTHENTICATION
Cognito	CREATE_AUTH_CHALLENGE
Cognito	VERIFY_AUTH_CHALLENGE_RESPONSE
S3	PUT_OBJECT
S3	DELETE_OBJECT
DYNAMODB	PUT_ITEM

Filters

events:
  MyRawEvent:
    filter: '{"detail_type": ["FooBar"]}'
    function: '{{namespace}}_foo_{{sandbox}}'
  MyFilterEvent:
    producer: default
    filter: '{"metadata": {"type": ["foo"]}}'
    function: '{{namespace}}_foo_{{sandbox}}'
  MyAbstractEvent:
    producer: default
    function: '{{namespace}}_foo_{{sandbox}}'

tc compiles JSON path filters to rules.

Patterns

If we have more complex patterns that can’t fit into basic producer/filter keys, we can specify a JSON blob containing the pattern

events:
  MyEvent:
    pattern: '{"detail-type": ["foo"], "source": ["aws.s3"]}'
    function: foo

Composition

Events can be composed with other entities. For example:

events:
  ApiEvent:
    function: function1

events:
  StateEvent:
    state: state-fqn
  MyOtherStateEvent:
  state: '{{namespace}}_{{sandbox}}'

Invoke

To invoke an event with just the payload data ($.detail), do:

tc invoke -s SANDBOX -e PROFILE -c events/MyEvent -p payload.json
# or from s3
tc invoke -s SANDBOX -e PROFILE -c events/MyEvent -p s3://bucket/payload.json

Visualization

To generate a visual flow:

tc compile -c events -f digraph | dot