Add output image capture mechanism

Authored-by: Leonhardt Koepsell <hello@lnhrdt.com>

Author: lnhrdt

CHANGELOG.md

@@ -9,11 +9,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [0.3.0] - 2025-04-23
+## [0.3.0] - 2025-04-24
 
 ### Added
 
 - Introduce container task extension with inputs and outputs.
+- Explicit capture methods for tracking image outputs at execution time.
 
 ## [0.2.1] - 2025-04-23
 

examples/buildpacks/build.gradle.kts

@@ -25,5 +25,8 @@ tasks {
         "/var/run/docker.sock:/var/run/docker.sock:ro",
       )
     }
+    doLast {
+      container.outputs.captureLocalImage("my-image:latest")
+    }
   }
 }

examples/dind-build/build.gradle.kts

@@ -22,5 +22,8 @@ tasks {
         "/var/run/docker.sock:/var/run/docker.sock:ro",
       )
     }
+    doLast {
+      container.outputs.captureLocalImage("my-image:latest")
+    }
   }
 }

examples/input-output-chaining/build.gradle.kts

@@ -33,5 +33,8 @@ tasks {
         "/var/run/docker.sock:/var/run/docker.sock:ro",
       )
     }
+    doLast {
+      container.outputs.captureLocalImage("my-image:latest")
+    }
   }
 }

src/main/kotlin/dev/codebandits/container/gradle/ContainerTaskExtension.kt

@@ -14,10 +14,10 @@ public abstract class ContainerTaskExtension(task: Task) {
 
   public class Inputs internal constructor(private val task: Task) {
     public fun localImage(imageReference: String) {
-      val trackingFile = task.getLocalImageTrackingFile(imageReference)
-      task.inputs.file(trackingFile.map { regularFile ->
-        writeLocalImageId(imageReference, regularFile)
-        regularFile
+      val trackingFileProvider = task.getLocalImageTrackingFile(imageReference)
+      task.inputs.file(trackingFileProvider.map { trackingFile ->
+        writeLocalImageId(imageReference, trackingFile)
+        trackingFile
       })
     }
 
@@ -34,29 +34,38 @@ public abstract class ContainerTaskExtension(task: Task) {
 
   public class Outputs internal constructor(private val task: Task) {
     public fun localImage(imageReference: String) {
-      val trackingFile = task.getLocalImageTrackingFile(imageReference)
-      task.outputs.file(trackingFile.map { regularFile ->
-        writeLocalImageId(imageReference, regularFile)
-        regularFile
+      val trackingFileProvider = task.getLocalImageTrackingFile(imageReference)
+      task.outputs.file(trackingFileProvider.map { trackingFile ->
+        writeLocalImageId(imageReference, trackingFile)
+        trackingFile
       })
-      task.doLast { writeLocalImageId(imageReference, trackingFile.get()) }
+    }
+
+    public fun captureLocalImage(imageReference: String) {
+      val trackingFile = task.getLocalImageTrackingFile(imageReference).get()
+      writeLocalImageId(imageReference, trackingFile)
     }
 
     public fun registryImage(imageReference: String, autoRefresh: Boolean = false) {
-      val trackingFile = task.getLocalImageTrackingFile(imageReference)
-      task.outputs.file(trackingFile.map { regularFile ->
-        if (autoRefresh || !regularFile.asFile.exists()) {
-          writeRegistryImageDigest(imageReference, regularFile)
+      val trackingFileProvider = task.getRegistryImageTrackingFile(imageReference)
+      task.outputs.file(trackingFileProvider.map { trackingFile ->
+        if (autoRefresh || !trackingFile.asFile.exists()) {
+          writeRegistryImageDigest(imageReference, trackingFile)
         }
-        regularFile
+        trackingFile
       })
       task.doLast {
-        val regularFile = trackingFile.get()
+        val regularFile = trackingFileProvider.get()
         if (autoRefresh || !regularFile.asFile.exists()) {
           writeRegistryImageDigest(imageReference, regularFile)
         }
       }
     }
+
+    public fun captureRegistryImage(imageReference: String) {
+      val trackingFile = task.getRegistryImageTrackingFile(imageReference).get()
+      writeRegistryImageDigest(imageReference, trackingFile)
+    }
   }
 }
 
@@ -74,17 +83,17 @@ private fun Task.getRegistryImageTrackingFile(
   return project.layout.buildDirectory.file("images/registry/$fileName")
 }
 
-private fun writeLocalImageId(imageReference: String, regularFile: RegularFile) {
-  val file = regularFile.asFile
+private fun writeLocalImageId(imageReference: String, trackingFile: RegularFile) {
+  val file = trackingFile.asFile
   if (!file.parentFile.exists()) {
     file.parentFile.mkdirs()
   }
   val imageId = Local.getImageId(imageReference)
   file.writeText(imageId ?: "")
 }
 
-private fun writeRegistryImageDigest(imageReference: String, regularFile: RegularFile) {
-  val file = regularFile.asFile
+private fun writeRegistryImageDigest(imageReference: String, trackingFile: RegularFile) {
+  val file = trackingFile.asFile
   if (!file.parentFile.exists()) {
     file.parentFile.mkdirs()
   }

src/testFeatures/kotlin/dev/codebandits/container/gradle/GroovySyntaxTest.kt

@@ -44,6 +44,9 @@ class GroovySyntaxTest : GradleProjectTest() {
             "/var/run/docker.sock:/var/run/docker.sock:ro",
           ] as String[])
         }
+        doLast {
+          container.outputs.captureLocalImage("$imageReference")
+        }
       }
       """.trimIndent()
     )

src/testFeatures/kotlin/dev/codebandits/container/gradle/TaskImagesTest.kt

@@ -109,6 +109,9 @@ class TaskImagesTest : GradleProjectTest() {
               "/var/run/docker.sock:/var/run/docker.sock:ro",
             )
           }
+          doLast {
+            container.outputs.captureLocalImage("$imageReference")
+          }
         }
       }
       """.trimIndent()

src/testToolIntegrations/kotlin/dev/codebandits/container/gradle/BuildpacksIntegrationTest.kt

@@ -61,6 +61,9 @@ class BuildpacksIntegrationTest : GradleProjectTest() {
               "/var/run/docker.sock:/var/run/docker.sock:ro",
             )
           }
+          doLast {
+            container.outputs.captureLocalImage("$imageReference")
+          }
         }
       }
       """.trimIndent()