New YAML manifest splitting from Helm fork changes multi-line string modifiers

[marvin-roesch]

After upgrading to Helm Controller 1.5.3 (via Flux 2.8.3) which ships helm/helm#31941, we've started seeing pods crash looping without any modifications to their originating chart. After some investigation, we found that rendered ConfigMaps (and other resources as well, very likely) had multi-line strings preserving final newlines (i.e. key: |\n...) modified to strip the final newline (i.e. key: |-\n...). The container running in the affected pods (haproxy) required its config to end in a newline, causing the crash.

This appears to happen when the end of the string value coincides with the end of the file. Here's an example:

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  value-a: |
    line1
    line2
  dummy-string: |
    line1
    line2

This gets rendered/applied by the Helm controller as follows:

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  value-a: |
    line1
    line2
  dummy-string: |-
    line1
    line2

The fix it seems would be to preserve final newlines when splitting documents on separators.

[matheuscscp]

I think this issue should be opened in Helm, @marvin-roesch can you please move it there? 🙏

[marvin-roesch]

I think this is actually only an issue with the most recent version and not a bigger Helm issue. We did not face this on Helm Controller 1.5.2.

[matheuscscp]

Sure but all this behavior is inside the Helm SDK. We made a temporary fork of Helm to fix the templating behavior, Helm SDK does all the templating, not helm-controller.

[matheuscscp]

@marvin-roesch I was just able to reproduce this in Helm CLI 4.0.0, but not in Helm CLI 3.20.0 using helm template --post-renderer:

helm-3.20.0 template test-chart . --post-renderer /home/matheus/.local/share/helm/plugins/label-injector/inject-labels.sh
---
# Source: demo-chart/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  labels:
    post-rendered: "true"
  name: my-config
data:
  value-a: |
    line1
    line2
  dummy-string: |
    line1
    line2

helm-4.0.0 template test-chart . --post-renderer label-injector
---
# Source: demo-chart/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  labels:
    post-rendered: "true"
  name: my-config
data:
  value-a: |
    line1
    line2
  dummy-string: |-
    line1
    line2

[stefanprodan]

@marvin-roesch there is nothing we can do about this in Flux, the Helm v4 SDK uses a new YAML parses that injects | - before passing the text stream to post renderers.

[matheuscscp]

xref: helm/helm#31948