Kubernetes Client for Crystal

Type-safe Kubernetes client with full API coverage generated from the OpenAPI spec.

Documentation: https://crystal-kubernetes-client.cloudnative.cr/

Features

• All 718 Kubernetes resource types (generated from swagger.json)
• Server-side apply pattern
• Watch loops with auto-reconnection
• Bearer tokens, client certs, exec providers (OIDC, AWS, GCP, Azure)
• Connection pooling
• Generic CRD client
• Zero-config in-cluster

Installation

dependencies:
  kubernetes-client:
    github: cloudnative-cr/kubernetes-client

Usage

require "kubernetes-client"

k8s = Kubernetes::Client.new

# List pods
pods = k8s.v1.pods.list_namespaced("default")
pods.items.each { |pod| puts pod.metadata.name }

# Scale deployment
k8s.v1.deployments.scale("default", "nginx", replicas: 10)

# Wait for pod
k8s.v1.pods.wait_until_ready("default", "nginx")

# Get logs
logs = k8s.v1.pods.logs("default", "nginx", tail_lines: 100)

Watch

k8s.watch("/api/v1/namespaces/default/pods") do |event|
  puts "#{event.type}: #{event.object.metadata.name}"
end

Custom Resources

struct MyCronTab
  include JSON::Serializable
  property metadata : Kubernetes::Metadata
  property spec : Spec

  struct Spec
    include JSON::Serializable
    property cron_spec : String
    property image : String
  end
end

crontabs = Kubernetes::Generic(MyCronTab).new(
  Kubernetes::Client.new,
  api_group: "stable.example.com",
  version: "v1",
  resource: "crontabs"
)

crontabs.list_namespaced("default").items.each { |ct| puts ct.metadata.name }
crontabs.watch_namespaced("default") { |event| reconcile(event.object) }

Development

git clone https://github.com/cloudnative-cr/kubernetes-client
cd kubernetes-client
shards install

# Generate API bindings
make download-spec
make generate

# Run tests (78 tests, ~146ms)
crystal spec

License

Apache 2.0