feat: allow to specify version of base Windows image

README.md

@@ -33,6 +33,7 @@ Only `image` parameter is mandatory - it's name of the resulting image.
         volumes = ['/my-folder'] // list of volumes; default: empty
         baseImage = 'my-org/our-base-image:1.2.3' // default: automatically choosed the best based on current Docker platform and Java version
         javaVersion = JavaVersion.VERSION_1_8 // Java version used to choose appropriate base Docker image; default: project.targetCompatibility
+        windowsBaseImageSpecifier = 'windowsservercore-ltsc2016' // suffix of AdoptOpenJDK Docker image that will be used as base image; another option is 'windowsservercore-1809'
         dockerfileLines = ['RUN apt-get ...'] // additional lines to include to Dockerfile; default: empty
         arguments = ['--server'] // arguments to be passed to your application; default: empty
         dockerBuildDirectory = project.file('my-directory') // directory where Dockerfile is created; default: "$buildDir/dockerJava"

src/main/groovy/cz/augi/gradle/dockerjava/DistDockerTask.groovy

@@ -65,7 +65,7 @@ class DistDockerTask extends DefaultTask {
     }
 
     private String getWindowsBaseImage() {
-        getAdoptOpenJdkBaseImageNamePrefix() + '-windowsservercore-ltsc2016'
+        getAdoptOpenJdkBaseImageNamePrefix() + (settings.windowsBaseImageSpecifier ? ('-' + settings.windowsBaseImageSpecifier) : '')
     }
 
     private String getLinuxBaseImage() {
@@ -189,6 +189,8 @@ interface DistDockerSettings {
     @Input @Optional
     JavaVersion getJavaVersion()
     @Input @Optional
+    String getWindowsBaseImageSpecifier()
+    @Input @Optional
     String getBaseImage()
     @Input @Optional
     Integer[] getPorts()

src/main/groovy/cz/augi/gradle/dockerjava/DockerJavaExtension.groovy

@@ -19,6 +19,7 @@ class DockerJavaExtension implements DistDockerSettings, DockerPushSettings {
     JavaVersion getJavaVersion() { customJavaVersion ?: project.targetCompatibility }
     void setJavaVersion(JavaVersion version) { customJavaVersion = version }
     private JavaVersion customJavaVersion
+    String windowsBaseImageSpecifier = 'windowsservercore-ltsc2016'
     String baseImage
     Integer[] ports = []
     String[] volumes = []