tkn task sign reserializes/reorders the entire YAML instead of only adding the signature annotation #2895

What happened

When signing a Task with tkn task sign -K key.pem -f task.yaml -f task.yaml, the command rewrites the entire YAML document: it reorders metadata keys (name, labels, annotations), reformats lists (e.g. params), and generally re-emits a canonicalized serialization rather than preserving the author's original file.

The only intended change is adding the tekton.dev/signature annotation. Everything else should be byte-for-byte preserved.

Why this is a problem

Catalog repositories (e.g. tektoncd-catalog/golang, tektoncd-catalog/git-clone) generate their Task YAMLs from base templates and run a CI check that regenerates and diffs the committed files (verify-generated). Because tkn task sign reserializes/reorders the whole document, the signed committed file no longer matches the generator output — producing a large spurious diff (hundreds of lines) that has nothing to do with the signature.

This forces downstream workarounds:

• normalizing both sides with yq -P (sorted keys) before diffing
• stripping the signature annotation before comparison

A signing operation should be minimally invasive: parse, add the annotation, and re-emit while preserving the original key order and formatting as much as possible.

Expected behavior

tkn task sign adds the tekton.dev/signature annotation and otherwise preserves the input serialization (key order, list formatting), so the diff between the unsigned and signed file is limited to the added annotation line.

Related

• tkn task sign adds empty 'resources: {}' to steps, causing strict decoding errors #2894 — tkn task sign also injects empty resources: {} into steps (separate but related serialization side effect)

Steps to reproduce

cat > task.yaml <<'YAML'
apiVersion: tekton.dev/v1
kind: Task
metadata:
  name: example
  labels:
    app.kubernetes.io/version: "1.0.0"
  annotations:
    tekton.dev/displayName: example
spec:
  steps:
    - name: run
      image: alpine
      script: echo hi
YAML

cp task.yaml before.yaml
tkn task sign task.yaml -K key.pem -f task.yaml
diff before.yaml task.yaml   # expect: only the signature annotation added; actual: whole file reordered