Checksumer (Kustomize plugin)

Kustomize transformer plugin that will calculate a unique sha1 checksum of a file or a file directory. Useful when tracking a specific version of a non Kubernetes resource represented by (an) external file(s), such as an external app configuration server state.

Roadmap:

• Support for IgnoredFilePrefix attribute within FileSpec

Requirements:

• Go 1.12
• Kustomize 3.1.0 built from source

  go get sigs.k8s.io/kustomize/v3/cmd/[email protected]
  

Usage:

• kustomization.yml

  apiVersion: kustomize.config.k8s.io/v1beta1
  kind: Kustomization
  resources:
    - deployment.yml
  transformers:
    - checksumer.yml
  

• deployment.yml

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: myapp
     labels:
       app: myapp
   spec:
     selector:
       matchLabels:
         app: myapp
     template:
       metadata:
         labels:
           app: myapp
       spec:
         containers:
           - image: myapp:somerevision
             name: myapp
  

• checksumer.yml

  apiVersion: github.com/oboukili
  kind: Checksumer
  metadata:
    name: myTransformer
  files:
    - key: arbitraryKey
      path: path/to/file
    - key: anotherArbitraryKey
      path: path/to/folder
      # Only applicable on folders, when true, will also take into account
      # all files present in subdirs to calculate a unique sha1 sum
      # (default to false)  
      recurse: true
  # Where the above keys will be inserted in the resulting transformed resources
  fieldSpecs:
    - path: metadata/annotations
      create: true
    - path: spec/template/metadata/annotations
      create: true
  

• results

  apiVersion: apps/v1
  kind: Deployment
  metadata:
   name: myapp
   labels:
     app: myapp
   annotations:
     arbitraryKey: (sha1sum string)
     anotherArbitraryKey: (sha1sum string)
  spec:
   selector:
     matchLabels:
       app: myapp
   template:
     metadata:
       labels:
         app: myapp
       annotations:
         arbitraryKey: (sha1sum string)
         anotherArbitraryKey: (sha1sum string)
     spec:
       containers:
         - image: myapp:somerevision
           name: myapp
  

Build

mkdir -p $HOME/.config/kustomize/plugin/github.com/oboukili
cd $HOME/.config/kustomize/plugin/github.com/oboukili
git clone https://github.com/oboukili/kustomize-plugin-checksumer -o checksumer
cd checksumer
go build -buildmode plugin -o Checksumer.so Checksumer.go

Run

PLUGIN_ROOT=$HOME/.config/kustomize/plugin kustomize build --enable_alpha_plugins path/to/kustomization/folder

Credits

Many thanks to the kustomize team for bringing us an awesome opensource configuration tool :)