Table of contents

• Overview
• Compatibility Matrix
• Examples
• Usage
  • Creating a client
  • Configuring a client
  • Client authentication
  • Client DSL
• Advance usage
• Installation
• License

Overview

Swift client for talking to a Kubernetes cluster via a fluent DSL based on SwiftNIO and the AysncHTTPClient.

• ☑ Covers all Kubernetes API Groups in v1.18.9
• ☑ Automatic configuration discovery
• ☑ DSL style API
  • ☑ Highest API version for the most common API Groups
  • ☐ Cover all API Groups/Versions
• ☑ Generic client support
• ☑ Swift-Logging support
• ☑ Loading resources from external sources
  • ☑ from files
  • ☑ from URLs
• ☑ Read Options
• ☑ List Options
• ☑ Delete Options
• ☐ PATCH API
• ☐ /scale API
• ☐ /status API
• ☐ Better resource watch support
• ☐ Better CRD support
• ☐ Controller/Informer support
• ☐ Swift Metrics
• ☐ Complete documentation
• ☐ End-to-end tests

Compatibility Matrix

• ✓ Exact match of API objects in both client and the Kubernetes version.
• - API objects mismatches either due to the removal of old API or the addition of new API. However, everything the client and Kubernetes have in common will work.

Examples

Concrete examples for using the Swiftkube tooling reside in the Swiftkube:Examples repository.

Usage

Creating a client

To create a client just import SwiftkubeClient and init an instance.

import SwiftkubeClient

let client = try KubernetesClient()

Configuring the client

The client tries to resolve a kube config automatically from different sources in the following order:

• Kube config file in the user's $HOME/.kube/config directory
• ServiceAccount token located at /var/run/secrets/kubernetes.io/serviceaccount/token and a mounted CA certificate, if it's running in Kubernetes.

Alternatively it can be configured manually, for example:

let caCert = try NIOSSLCertificate.fromPEMFile(caFile)
let authentication = KubernetesClientAuthentication.basicAuth(
    username: "admin", 
    password: "admin"
)

let config = KubernetesClientConfig(
    masterURL: "https://kubernetesmaster",
    namespace: "default",
    authentication: authentication,
    trustRoots: NIOSSLTrustRoots.certificates(caCert),
    insecureSkipTLSVerify: false
)

let client = KubernetesClient(config: config)

Client authentication

The following authentication schemes are supported:

• Basic Auth: .basicAuth(username: String, password: String)
• Bearer Token: .bearer(token: String)
• Client certificate: .x509(clientCertificate: NIOSSLCertificate, clientKey: NIOSSLPrivateKey)

Client DSL

SwiftkubeClient defines convenience API to work with Kubernetes resources. Using this DSL is the same for all resources.

The examples use the blocking wait() for brevity. API calls return EventLoopFutures that can be composed and acted upon in an asynchronous way.

Currently only a subset of all API groups are accessible via the DSL. See Advanced usage for mor details.

List resources

let namespaces = try client.namespaces.list().wait()
let deployments = try client.appsV1.deployments.list(in: .allNamespaces).wait()
let roles = try client.rbacV1.roles.list(in: .namespace("ns")).wait()

You can filter the listed resources or limit the returned list size via the ListOptions:

let deployments = try client.appsV1.deployments.list(in: .allNamespaces, options: [
	.labelSelector(.eq(["app": "nginx"])),
	.labelSelector(.notIn(["env": ["dev", "staging"]])),
	.labelSelector(.exists(["app", "env"])),
	.fieldSelector(.eq(["status.phase": "Running"])),
	.resourceVersion("9001"),
	.limit(20),
	.timeoutSeconds(10)
]).wait()

Get a resource

let namespace = try client.namespaces.get(name: "ns").wait()
let deployment = try client.appsV1.deployments.get(in: .namespace("ns"), name: "nginx").wait()
let roles = try client.rbacV1.roles.get(in: .namespace("ns"), name: "role").wait()

You can also provide the following ReadOptions:

let deployments = try client.appsV1.deployments.get(in: .allNamespaces, options: [
	.pretty(true),
	.exact(false),
	.export(true)
]).wait()

Delete a resource

try.client.namespaces.delete(name: "ns").wait()
try client.appsV1.deployments.delete(in: .namespace("ns"), name: "nginx").wait()
try client.rbacV1.roles.delete(in: .namespace("ns"), name: "role").wait()

You can pass an instance of meta.v1.DeleteOptions to control the behaviour of the delete operation:

let deletOptions = meta.v1.DeleteOptions(
	gracePeriodSeconds: 10,
	propagationPolicy: "Foreground"
)
try client.pods.delete(in: .namespace("ns"), name: "nginx", options: deleteOptions).wait()

Create and update a resource

Resources can be created/updated directly or via the convenience builders defined in SwiftkubeModel

// Create a resouce instance and post it
let configMap = core.v1.ConfigMap(
	metadata: meta.v1.Metadata(name: "test"),
	data: ["foo": "bar"]
}
try cm = try client.configMaps.create(inNamespace: .default, configMap).wait()


// Or inline via a builder
let pod = try client.pods.create(inNamespace: .default) {
        sk.pod {
            $0.metadata = sk.metadata(name: "nginx")
            $0.spec = sk.podSpec {
                $0.containers = [
                    sk.container(name: "nginx") {
                        $0.image = "nginx"
                    }
                ]
            }
        }
    }
    .wait()

Watch a resource

:warning: Watching a resource opens a persistent connection until the client is closed.

let task: HTTPClient.Task<Void> = client.pods.watch(in: .namespace("default")) { (event, pod) in
    print("\(event): \(pod)")
}

// The task can be cancelled later to stop watching
task.cancel()

Follow logs

:warning: Following a pod logs opens a persistent connection until the client is closed.

let task: HTTPClient.Task<Void> = client.pods.follow(in: .namespace("default"), name: "nginx") { (line) in
    print(line)
}

// The task can be cancelled later o stop following
task.cancel()

Advanced usage

Loading from external sources

A resource can be loaded from a file or a URL:

// Load from URL, e.g. a file
let url = URL(fileURLWithPath: "/path/to/manifest.yaml")
let deployment = try apps.v1.Deployment.load(contentsOf: url)

API groups

To access API groups not defined as a DSL, e.g. rbac.v1beta1 a dedicated client can still be intantiated. A client can be either namespace scoped or cluster scoped:

try client.namespaceScoped(for: rbac.v1beta1.RoleBinding.self).list(in: .allNamespaces).wait()
try client.clusterScoped(for: rbac.v1beta1.ClusterRole.self).list().wait()

Type-erased usage

Often when working with Kubernetes the concrete type of the resource is not known or not relevant, e.g. when creating resources from a YAML manifest file. Other times the type or kind of the resource must be derived at runtime given its string representation.

Leveraging SwiftkubeModel's type-erased resource implementations AnyKubernetesAPIResource and its corresponding List-Type AnyKubernetesAPIResourceList it is possible to have a generic client instance, which must be initialized with a GroupVersionKind type:

guard let gvk = try? GroupVersionKind(for: "deployment") else {
   // handle this
}

// Get by name
let resource: AnyKubernetesAPIResource = try client.for(gvk: gvk)
    .get(in: .default , name: "nginx")
    .wait()

// List all
let resources: AnyKubernetesAPIResourceList = try client.for(gvk: gvk)
    .list(in: .allNamespaces)
    .wait()

GroupVersionKind

A GroupVersionKind can be initialized from:

• KubernetesAPIResource instance
• KubernetesAPIResource type
• Full API Group string
• Lowecassed singular resource kind
• Lowercased plural resource name
• lowecased short resource name

let deployment = ..
let gvk = GroupVersionKind(of: deployment)
let gvk = GroupVersionKind(of: apps.v1.Deployment.self)
let gvk = GroupVersionKind(rawValue: "apps/v1/Deployment")
let gvk = GroupVersionKind(for: "deployment")
let gvk = GroupVersionKind(for: "deployments")
let gvk = GroupVersionKind(for: "deploy")

Installation

To use the SwiftkubeModel in a SwiftPM project, add the following line to the dependencies in your Package.swift file:

.package(name: "SwiftkubeClient", url: "https://github.com/swiftkube/client.git", from: "0.4.0"),

then include it as a dependency in your target:

import PackageDescription

let package = Package(
    // ...
    dependencies: [
        .package(name: "SwiftkubeClient", url: "https://github.com/swiftkube/client.git", from: "0.4.0")
    ],
    targets: [
        .target(name: "<your-target>", dependencies: [
            .product(name: "SwiftkubeClient", package: "SwiftkubeClient"),
        ])
    ]
)

Then run swift build.

License

Swiftkube project is licensed under version 2.0 of the Apache License. See LICENSE for more details.