tart pull: be more liberal when accepting local image as argument (#70)

* tart pull: be more liberal when accepting local image as argument

* Update Sources/tart/Commands/Pull.swift

Co-authored-by: Fedor Korotkov <fedor.korotkov@gmail.com>

* Single sentence and consistent capitalization

Co-authored-by: Fedor Korotkov <fedor.korotkov@gmail.com>

.goreleaser.yml

@@ -35,3 +35,5 @@ brews:
     homepage: https://github.com/cirruslabs/tart
     description: Run macOS VMs on Apple Silicon
     skip_upload: auto
+    custom_block: |
+      depends_on :macos => :monterey

README.md

@@ -8,7 +8,7 @@ Built by CI engineers for your automation needs. Here are some highlights of Tar
 * Use Tart Packer Plugin to automate VM creation.
 * Built-in CI integration.
 
-Try running a Tart VM on your Apple Silicon device (will download a 25 GB image):
+Try running a Tart VM on your Apple Silicon device running macOS Monterey or later (will download a 25 GB image):
 
 ```shell
 brew install cirruslabs/cli/tart
@@ -20,9 +20,13 @@ tart run monterey-base
 
 ## CI Integration
 
-[Cirrus CLI](https://github.com/cirruslabs/cirrus-cli) is an open-sourced CI-agnostic tool that can run workloads
-inside containers via Docker or Podman and now inside macOS VMs via Tart. Put the following `.cirrus.yml` file
-in the root of your repository:
+Tart itself is only responsible for managing virtual machines, but we've built Tart support into a tool called Cirrus CLI
+also developed by Cirrus Labs. [Cirrus CLI](https://github.com/cirruslabs/cirrus-cli) is a command line tool with
+one configuration format to execute common CI steps (run a script, cache a folder, etc.) locally or in any CI system.
+We built Cirrus CLI to solve "But it works on my machine!" problem.
+
+Here is an example of a `.cirrus.yml` configuration file which will start a Tart VM, will copy over working directory and
+will run scripts and [other instructions](https://cirrus-ci.org/guide/writing-tasks/#supported-instructions) inside the virtual machine:
 
 ```yaml
 task:
@@ -37,7 +41,7 @@ task:
     - sleep 15
 ```
 
-Run it locally or in CI with the following command:
+Put the above `.cirrus.yml` file in the root of your repository and run it with the following command:
 
 ```shell
 brew install cirruslabs/cli/cirrus
@@ -78,7 +82,7 @@ Please refer to `tart set --help` for additional details.
 
 ### Building with Packer
 
-Please refer to [Tart Packer Plugin reposiotry](https://github.com/cirruslabs/packer-plugin-tart) for setup instructions.
+Please refer to [Tart Packer Plugin repository](https://github.com/cirruslabs/packer-plugin-tart) for setup instructions.
 Here is an example of a template to build `monterey-base` local image based of a remote image:
 
 ```json

Sources/tart/Commands/Pull.swift

@@ -10,6 +10,14 @@ struct Pull: AsyncParsableCommand {
 
   func run() async throws {
     do {
+      // Be more liberal when accepting local image as argument,
+      // see https://github.com/cirruslabs/tart/issues/36
+      if VMStorageLocal().exists(remoteName) {
+        print("\"\(remoteName)\" is a local image, nothing to pull here!")
+
+        Foundation.exit(0)
+      }
+
       let remoteName = try RemoteName(remoteName)
       let registry = try Registry(host: remoteName.host, namespace: remoteName.namespace)
 

Sources/tart/OCI/Registry.swift

@@ -8,11 +8,31 @@ enum RegistryError: Error {
 }
 
 struct TokenResponse: Decodable {
-  let creationTime = Date()
-  
+  let defaultIssuedAt = Date()
+  let defaultExpiresIn = 60
+
   var token: String
-  var expires_in: Int?
-  
+  var expiresIn: Int?
+  var issuedAt: Date?
+
+  static func parse(fromData: Data) throws -> Self {
+    let decoder = JSONDecoder()
+
+    decoder.keyDecodingStrategy = .convertFromSnakeCase
+
+    // RFC3339 date formatter from Apple's documentation[1]
+    //
+    // [1]: https://developer.apple.com/documentation/foundation/dateformatter
+    let dateFormatter = DateFormatter()
+    dateFormatter.locale = Locale(identifier: "en_US_POSIX")
+    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+    dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
+
+    decoder.dateDecodingStrategy = .formatted(dateFormatter)
+
+    return try decoder.decode(TokenResponse.self, from: fromData)
+  }
+
   var tokenExpiresAt: Date {
     get {
       // Tokens can expire and expire_in field is used to determine when:
@@ -22,8 +42,8 @@ struct TokenResponse: Decodable {
       // >a token should never be returned with less than 60 seconds to live.
       //
       // [1]: https://docs.docker.com/registry/spec/auth/token/#requesting-a-token
-      
-      creationTime + TimeInterval(expires_in ?? 60)
+
+      (issuedAt ?? defaultIssuedAt) + TimeInterval(expiresIn ?? defaultExpiresIn)
     }
   }
   
@@ -233,7 +253,7 @@ class Registry {
         + "while retrieving an authentication token", details: String(decoding: tokenResponseRaw, as: UTF8.self))
     }
 
-    currentAuthToken = try JSONDecoder().decode(TokenResponse.self, from: tokenResponseRaw)
+    currentAuthToken = try TokenResponse.parse(fromData: tokenResponseRaw)
   }
 
   private func authAwareRequest(request: URLRequest) async throws -> (Data, HTTPURLResponse) {

Tests/TartTests/TokenResponseTests.swift

@@ -0,0 +1,38 @@
+import XCTest
+@testable import tart
+
+final class TokenResponseTests: XCTestCase {
+  func testBasic() throws {
+    let tokenResponseRaw = Data("{\"token\":\"some token\"}".utf8)
+    let tokenResponse = try TokenResponse.parse(fromData: tokenResponseRaw)
+
+    XCTAssertEqual(tokenResponse.token, "some token")
+
+    let expectedTokenExpiresAtRange = Date()...Date().addingTimeInterval(60)
+    XCTAssertTrue(expectedTokenExpiresAtRange.contains(tokenResponse.tokenExpiresAt))
+
+    XCTAssertTrue(tokenResponse.isValid)
+  }
+
+  func testExpirationBasic() throws {
+    let tokenResponseRaw = Data("{\"token\":\"some token\",\"expires_in\":2}".utf8)
+    let tokenResponse = try TokenResponse.parse(fromData: tokenResponseRaw)
+
+    XCTAssertEqual(tokenResponse.expiresIn, 2)
+
+    let expectedTokenExpiresAtRange = Date()...Date().addingTimeInterval(2)
+    XCTAssertTrue(expectedTokenExpiresAtRange.contains(tokenResponse.tokenExpiresAt))
+
+    XCTAssertTrue(tokenResponse.isValid)
+    _ = XCTWaiter.wait(for: [expectation(description: "Wait 3 seconds for the token to become invalid")], timeout: 2)
+    XCTAssertFalse(tokenResponse.isValid)
+  }
+
+  func testExpirationWithIssuedAt() throws {
+    let tokenResponseRaw = Data("{\"token\":\"some token\",\"expires_in\":3600,\"issued_at\":\"1970-01-01T00:00:00Z\"}".utf8)
+    let tokenResponse = try TokenResponse.parse(fromData: tokenResponseRaw)
+
+    XCTAssertEqual(Date(timeIntervalSince1970: 3600), tokenResponse.tokenExpiresAt)
+    XCTAssertFalse(tokenResponse.isValid)
+  }
+}