crdutil

README

CRD Apply Tool

This tool is designed to help deploy and manage Custom Resource Definitions (CRDs) in a Kubernetes cluster. It applies all CRDs found in specified directories, providing a solution to some of the limitations of Helm when it comes to managing CRDs.

Motivation

While Helm is commonly used for managing Kubernetes resources, it has certain restrictions with CRDs:

• CRDs placed in Helm's top-level crds/ directory are not updated on upgrades or rollbacks.
• Placing CRDs in Helm’s templates/ directory is not entirely safe, as deletions and upgrades of CRDs are not always handled properly.

This tool offers a more reliable way to apply CRDs, ensuring they are created or updated as needed.

Features

• Apply CRDs from multiple directories: Allows specifying multiple directories containing CRD YAML manifests.
• Recursive directory search: Walks through each specified directory to find and apply all YAML files.
• Safe update mechanism: Checks if a CRD already exists; if so, it updates it with the latest version.
• Handles multiple YAML documents: Supports files containing multiple CRD documents separated by YAML document delimiters.

Usage

Compile and run the tool by providing the -crds-dir flag with paths to the directories containing the CRD YAML files:

go build -o crd-apply-tool
./crd-apply-tool -crds-dir /path/to/crds1 -crds-dir /path/to/crds2

In a Helm pre-install hook it can look like:

apiVersion: batch/v1
kind: Job
metadata:
  name: upgrade-crd
  annotations:
    "helm.sh/hook": pre-install,pre-upgrade
    "helm.sh/hook-weight": "1"
    "helm.sh/hook-delete-policy": hook-succeeded,before-hook-creation
spec:
  template:
    metadata:
      name: upgrade-crd
    spec:
      containers:
        - name: upgrade-crd
          image: path-to-your/crd-apply-image
          imagePullPolicy: IfNotPresent
          command:
            - /apply-crds
          args:
              - --crds-dir=/crds/operator

Note: the image must contain all your CRDs in e.g. the /crds/operator directory.

Flags

• -crds-dir (required): Specifies a directory path that contains the CRD manifests in YAML format. This flag can be provided multiple times to apply CRDs from multiple directories.

Documentation

Index

• func EnsureCRDsCmd()
• type StringList
  • func (s *StringList) Set(value string) error
  • func (s *StringList) String() string

Functions

func EnsureCRDsCmd

func EnsureCRDsCmd()

EnsureCRDsCmd reads each YAML file in the directory, splits it into documents, and applies each CRD to the cluster. The parameter --crds-dir is required and should point to the directory containing the CRD manifests.

Types

type StringList

type StringList []string

func (*StringList) Set

func (s *StringList) Set(value string) error

func (*StringList) String

func (s *StringList) String() string