RFR(S): 8221342: [TESTBUG] Generate Dockerfile for docker testing

[Severin Gehwolf]

Hi Misha,

First, nice work! Thanks for doing this. I like it. It works for me and
my workflow (and the old docker version I have). A few comments below.

On Fri, 2019-03-22 at 18:07 -0700, mikhailo.seledtsov at oracle.com wrote:
> Please review this improvement to docker/container related testing in 
> HotSpot and JDK.
> This change came out of discussion for "8221221 make test 
> TEST="jtreg:test/hotspot/jtreg/runtime/containers" failed on Ubuntu 
> 18.04". This fix is more generic, allowing to specify platform-specific 
> docker base images, as well custom base images specified via test 
> properties at test execution time. Also, it eliminates duplication 
> (duplicate Dockerfile-xyz).
> 
>      JBS: https://bugs.openjdk.java.net/browse/JDK-8221342
>      Webrev: http://cr.openjdk.java.net/~mseledtsov/8221342.01/

We should get aarch64 (et.al) image users on board with testing that
patch too.

+    static String getBaseImageVersion() {
+        String version = System.getProperty("jdk.test.docker.image.version");
+        if (version != null) {
+            System.out.println("DockerfileConfig: using custom image version: " + version);
+            return version;
+        }
+
+        switch (Platform.getOsArch()) {
+            case "aarch64":
+            case "ppc64le":
+            case "s390x":
+                return "";
+            default:
+                return "7.6";
+        }

And:

+        generateDockerFile(buildDir.resolve("Dockerfile"),
+                           DockerfileConfig.getBaseImageName(),
+                           DockerfileConfig.getBaseImageVersion());
 
         // Build the docker
         execute("docker", "build", "--no-cache", "--tag", imageName, buildDir.toString())
@@ -250,6 +245,18 @@
     }
 
 
+    private static void generateDockerFile(Path dockerfile, String baseImage,
+                                           String baseImageVersion) throws Exception {
+        String template =
+            "FROM %s:%s\n" +
+            "COPY /jdk /jdk\n" +
+            "ENV JAVA_HOME=/jdk\n" +
+            "CMD [\"/bin/bash\"]\n";
+        String dockerFileStr = String.format(template, baseImage, baseImageVersion);

So for the default case on aarch64 the FROM tag will look like:

"FROM aarch64/ubuntu:"

That's not a legal image spec. Instead of returning the empty string
for getBaseImageVersion() we should return "latest" because
"aarch64/ubuntu:latest" is a valid image spec and it reflects current
behaviour.

Other than that, looks good!

Thanks,
Severin