ContainerRegistry: Throw an error instead of asserting when registry digest does not match expectations

Author: euanh

Sources/ContainerRegistry/RegistryClient.swift

@@ -19,20 +19,24 @@ import FoundationNetworking
 import HTTPTypes
 import Basics
 
-enum RegistryClientError: Error {
+public enum RegistryClientError: Error {
     case registryParseError(String)
     case invalidRegistryPath(String)
     case invalidUploadLocation(String)
     case invalidDigestAlgorithm(String)
+    case digestMismatch(expected: String, registry: String)
 }
 
 extension RegistryClientError: CustomStringConvertible {
-    var description: String {
+    /// Human-readable description of a RegistryClientError
+    public var description: String {
         switch self {
         case let .registryParseError(reference): return "Unable to parse registry: \(reference)"
         case let .invalidRegistryPath(path): return "Unable to construct URL for registry path: \(path)"
         case let .invalidUploadLocation(location): return "Received invalid upload location from registry: \(location)"
         case let .invalidDigestAlgorithm(digest): return "Invalid or unsupported digest algorithm: \(digest)"
+        case let .digestMismatch(expected, registry):
+            return "Digest mismatch: expected \(expected), registry sent \(registry)"
         }
     }
 }

Sources/containertool/Extensions/RegistryClient+CopyBlobs.swift

@@ -39,6 +39,9 @@ extension RegistryClient {
         log("Layer \(digest): pushing")
         let uploaded = try await destClient.putBlob(repository: destRepository, data: blob)
         log("Layer \(digest): done")
-        assert("\(digest)" == uploaded.digest)
+
+        guard "\(digest)" == uploaded.digest else {
+            throw RegistryClientError.digestMismatch(expected: "\(digest)", registry: uploaded.digest)
+        }
     }
 }