localregistry

README

Local Registry Discovery

A Go implementation of the local registry discovery protocol.

Background

Local clusters like Kind, K3d, Minikube, and Microk8s let users iterate on Kubernetes quickly in a hermetic environment. To avoid network round-trip latency, these clusters can be configured to pull from a local, insecure registry.

KEP 1755 proposes a standard for how these clusters should expose their support for this feature, so that tooling can interoperate with them without redundant configuration.

Try it

Install the kubectl plugin:

go install github.com/tilt-dev/localregistry-go/cmd/kubectl-local_registry

Run:

kubectl local-registry get

If your cluster explicitly advertises a local registry, this tool will print the fields of LocalRegistryHostingV1.

Use it in your tool

This repo contains library code that reads the local registry configuration from a Kubernetes cluster, given a instance of the Go Kubernetes client.

License

Copyright 2020 Windmill Engineering

Licensed under the Apache License, Version 2.0

Documentation

Index

• Constants
• type LocalRegistryHostingV1
  • func Discover(ctx context.Context, core apiv1.CoreV1Interface) (LocalRegistryHostingV1, error)

Constants

const ConfigMapField = "localRegistryHosting.v1"

const ConfigMapName = "local-registry-hosting"

const ConfigMapNamespace = "kube-public"

const SampleConfigMap = `` /* 318-byte string literal not displayed */

Types

type LocalRegistryHostingV1

type LocalRegistryHostingV1 struct {
	// Host documents the host (hostname and port) of the registry, as seen from
	// outside the cluster.
	//
	// This is the registry host that tools outside the cluster should push images
	// to.
	Host string `json:"host,omitempty" yaml:"host,omitempty"`

	// HostFromClusterNetwork documents the host (hostname and port) of the
	// registry, as seen from networking inside the container pods.
	//
	// This is the registry host that tools running on pods inside the cluster
	// should push images to. If not set, then tools inside the cluster should
	// assume the local registry is not available to them.
	HostFromClusterNetwork string `json:"hostFromClusterNetwork,omitempty" yaml:"hostFromClusterNetwork,omitempty"`

	// HostFromContainerRuntime documents the host (hostname and port) of the
	// registry, as seen from the cluster's container runtime.
	//
	// When tools apply Kubernetes objects to the cluster, this host should be
	// used for image name fields. If not set, users of this field should use the
	// value of Host instead.
	//
	// Note that it doesn't make sense semantically to define this field, but not
	// define Host or HostFromClusterNetwork. That would imply a way to pull
	// images without a way to push images.
	HostFromContainerRuntime string `json:"hostFromContainerRuntime,omitempty" yaml:"hostFromContainerRuntime,omitempty"`

	// Help contains a URL pointing to documentation for users on how to set
	// up and configure a local registry.
	//
	// Tools can use this to nudge users to enable the registry. When possible,
	// the writer should use as permanent a URL as possible to prevent drift
	// (e.g., a version control SHA).
	//
	// When image pushes to a registry host specified in one of the other fields
	// fail, the tool should display this help URL to the user. The help URL
	// should contain instructions on how to diagnose broken or misconfigured
	// registries.
	Help string `json:"help,omitempty" yaml:"help,omitempty"`
}

LocalRegistryHostingV1 describes a local registry that developer tools can connect to. A local registry allows clients to load images into the local cluster by pushing to this registry.

func Discover

func Discover(ctx context.Context, core apiv1.CoreV1Interface) (LocalRegistryHostingV1, error)

Check if the cluster advertises support for a local registry.

If no registry advertised, returns an empty struct.

If a registry is advertised but we don't understand the config map, returns an error.