CEL overlay from headers error: couldn't unmarshal json from the TriggerTemplate: invalid character "X" after object key:value pair

[Timoses]

CEL overlay from headers error: couldn't unmarshal json from the TriggerTemplate: invalid character "X" after object key:value pair

[Timoses]

The initial log line gave a hint:

[tekton-triggers-core-interceptors-7948fbb949-rmkpl] {"level":"info","ts":1690891975.432717,"caller":"server/server.go:154","msg":"Interceptor response is: &{Extensions:map[event:[push]] Continue:true Status:{Code:OK Message:}}"}

It states:

&{Extensions:map[event:[push]] 

Using the following solves the issue:

  interceptors:
  - params:
    - name: overlays
      value:
      - expression: header['X-Gitea-Event'][0]
        key: event
    ref:
      kind: ClusterInterceptor
      name: cel

(Note accessing the first array item of the header field)

[Timoses]

Documented here: https://tekton.dev/docs/triggers/cel_expressions/#list-of-extensions