Checking a Helm Chart Refactor with Manifest Diff

Source: Dev.to

Introduction

When refactoring Helm charts—whether moving logic, simplifying templates, merging files, or cleaning up loops and functions—the goal is to keep the final Kubernetes manifests unchanged. Rendering the manifests before and after the refactor and comparing them provides a simple verification method.

Prerequisites

• yq – used to sort Kubernetes manifests.

  brew install yq

• dyff – compares YAML files, highlighting real configuration changes while ignoring formatting differences.

  brew install dyff

Steps

Step 1: Render manifests before changes

helm template my-release ./chart -f values.yaml > before.yaml

Step 2: Refactor the Helm chart

(Make your desired changes to the chart files.)

Step 3: Render manifests again

helm template my-release ./chart -f values.yaml > after.yaml

Step 4: Sort manifests (to avoid noise from ordering)

yq -s 'sort_by(.kind, .metadata.name)' before.yaml > before_sorted.yaml
yq -s 'sort_by(.kind, .metadata.name)' after.yaml > after_sorted.yaml

Sorting prevents differences caused only by resource order changes.

Step 5: Compare manifests

dyff between before_sorted.yaml after_sorted.yaml

If no differences are reported, the refactor did not alter the resulting Kubernetes manifests, indicating that the refactor is safe.