Refactor configuration builers and add support for overriding the current k8s context (#47)

* Refactor configuration builers and add support for overriding the current k8s context

* reformatted with tab indents

* reformatted swift-format

* Refactor KubeConfigLoader as KubeConfig extensions

* Clean up comments

* Add back a few convenience functions

* swiftformat

---------

Co-authored-by: nefilim <nefilim@nefilim.org>

Author: nefilim

Sources/SwiftkubeClient/Client/KubernetesClient.swift

@@ -104,56 +104,6 @@ public actor KubernetesClient {
 		}()
 	#endif
 
-	/// Create a new instance of the Kubernetes client.
-	///
-	/// The client tries to resolve a `kube config` automatically from different sources in the following order:
-	///
-	/// - A Kube config file at path of environment variable `KUBECONFIG` (if set)
-	/// - A 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.
-	///
-	/// Returns `nil` if a configuration can't be found.
-	///
-	/// - Parameters:
-	///    - provider: A ``EventLoopGroupProvider`` to specify how ``EventLoopGroup`` will be created.
-	///    - logger: The logger to use for this client.
-	public init?(
-		provider: HTTPClient.EventLoopGroupProvider = .shared(MultiThreadedEventLoopGroup(numberOfThreads: 1)),
-		logger: Logger? = nil
-	) {
-		let logger = logger ?? SwiftkubeClient.loggingDisabled
-
-		guard
-			let config = KubernetesClientConfig.initialize(logger: logger)
-		else {
-			return nil
-		}
-
-		self.init(config: config, provider: provider, logger: logger)
-	}
-
-	/// Create a new instance of the Kubernetes client.
-	///
-	/// - Parameters:
-	///    - url: The url to load the configuration from for this client instance. It can be a local file or remote URL.
-	///    - provider: A ``EventLoopGroupProvider`` to specify how ``EventLoopGroup`` will be created.
-	///    - logger: The logger to use for this client.
-	public init?(
-		fromURL url: URL,
-		provider: HTTPClient.EventLoopGroupProvider = .shared(MultiThreadedEventLoopGroup(numberOfThreads: 1)),
-		logger: Logger? = nil
-	) {
-		let logger = logger ?? SwiftkubeClient.loggingDisabled
-
-		guard
-			let config = KubernetesClientConfig.create(fromUrl: url, logger: logger)
-		else {
-			return nil
-		}
-
-		self.init(config: config, provider: provider, logger: logger)
-	}
-
 	/// Create a new instance of the Kubernetes client.
 	///
 	/// - Parameters:
@@ -216,6 +166,25 @@ public actor KubernetesClient {
 		)
 	}
 
+	public static func forContext(
+		context: String,
+		provider: HTTPClient.EventLoopGroupProvider = .shared(MultiThreadedEventLoopGroup(numberOfThreads: 1)),
+		logger: Logger? = nil
+	) throws -> KubernetesClient? {
+		try KubeConfig.fromLocalEnvironment()
+			.flatMap { try KubernetesClientConfig.from(kubeConfig: $0, context: context, logger: logger) }
+			.map { KubernetesClient(config: $0) }
+	}
+
+	public static func forCurrentContext(
+		provider: HTTPClient.EventLoopGroupProvider = .shared(MultiThreadedEventLoopGroup(numberOfThreads: 1)),
+		logger: Logger? = nil
+	) throws -> KubernetesClient? {
+		try KubeConfig.fromLocalEnvironment()
+			.flatMap { try KubernetesClientConfig.from(kubeConfig: $0, logger: logger) }
+			.map { KubernetesClient(config: $0) }
+	}
+
 	/// Shuts down the client gracefully.
 	///
 	/// This function uses a completion instead of an EventLoopFuture, because the underlying event loop will be closed

Sources/SwiftkubeClient/Config/KubeConfig.swift

@@ -15,6 +15,9 @@
 //
 
 import Foundation
+import Logging
+import NIOSSL
+import Yams
 
 // MARK: - KubeConfig
 
@@ -49,6 +52,35 @@ public struct KubeConfig: Codable, Sendable {
 	public var currentContext: String?
 }
 
+public extension KubeConfig {
+
+	static func from(config: String) throws -> KubeConfig {
+		let decoder = YAMLDecoder()
+
+		return try decoder.decode(KubeConfig.self, from: config)
+	}
+
+	static func from(url: URL) throws -> KubeConfig {
+		let contents = try String(contentsOf: url, encoding: .utf8)
+
+		return try from(config: contents)
+	}
+
+	static func fromLocalEnvironment(envVar: String = "KUBECONFIG", logger: Logger? = nil) throws -> KubeConfig? {
+		let kubeConfigURL: URL? = ProcessInfo.processInfo.environment[envVar].map { URL(fileURLWithPath: $0) } ?? ProcessInfo.processInfo.environment["HOME"].map { URL(fileURLWithPath: $0 + "/.kube/config") }
+
+		guard let kubeConfigURL else {
+			logger?.warning(
+				"Skipping local kubeconfig loading, neither environment variable KUBECONFIG nor HOME are set."
+			)
+			return nil
+		}
+		logger?.info("Loading configuration from \(kubeConfigURL)")
+
+		return try from(url: kubeConfigURL)
+	}
+}
+
 // MARK: - Cluster
 
 /// Cluster contains information about how to communicate with a kubernetes cluster.