JENKINS-66171: Get built docker image ID using --iidfile (#82)

Previously we were capturing `docker build` output, which led to some problems:
1. Other programs could print similar strings, which would match but did not
contain the image ID. This was fixed by taking the last capture as image ID.
2. `docker build` output has changed in version 23, so now we'd have to match
the output twice. First pass for docker < 23, and another for >= 23

Docker has had the `--iidfile` option for some time now, so switch to using it.
It is a much less fragile way to capture the image ID.

Tested with Docker 20.10.23 and 23.0.1

Co-authored-by: Jon Hermansen <[email protected]>

src/main/java/com/cloudbees/jenkins/plugins/docker_build_env/Docker.java

@@ -8,7 +8,6 @@
 import hudson.model.TaskListener;
 import hudson.util.ArgumentListBuilder;
 import org.apache.commons.io.LineIterator;
-import org.apache.commons.io.output.TeeOutputStream;
 import org.apache.commons.lang.StringUtils;
 
 import org.jenkinsci.plugins.docker.commons.credentials.DockerRegistryEndpoint;
@@ -29,8 +28,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 /**
  * @author <a href="mailto:[email protected]">Nicolas De Loof</a>
@@ -110,9 +107,11 @@ public boolean pullImage(String image) throws IOException, InterruptedException
 
 
     public String buildImage(FilePath workspace, String dockerfile, boolean forcePull, boolean noCache) throws IOException, InterruptedException {
+        FilePath tempImageIdFile = workspace.createTempFile("dcbep-", ".iid");
 
         ArgumentListBuilder args = dockerCommand()
-            .add("build");
+            .add("build")
+            .add("--iidfile", tempImageIdFile.getRemote());
 
         if (forcePull)
             args.add("--pull");
@@ -126,36 +125,25 @@ public String buildImage(FilePath workspace, String dockerfile, boolean forcePul
         args.add("--label", "jenkins-project=" + this.build.getProject().getName());
         args.add("--label", "jenkins-build-number=" + this.build.getNumber());
 
-        OutputStream logOutputStream = listener.getLogger();
+        OutputStream out = listener.getLogger();
         OutputStream err = listener.getLogger();
-
-        ByteArrayOutputStream resultOutputStream = new ByteArrayOutputStream();
-        TeeOutputStream teeOutputStream = new TeeOutputStream(logOutputStream, resultOutputStream);
-
         int status = launcher.launch()
-                .envs(getEnvVars())
-                .cmds(args)
-                .stdout(teeOutputStream).stderr(err).join();
+            .envs(getEnvVars())
+            .cmds(args)
+            .stdout(out).stderr(err).join();
         if (status != 0) {
             throw new RuntimeException("Failed to build docker image from project Dockerfile");
         }
 
-        Pattern pattern = Pattern.compile("Successfully built (.*)");
-        Matcher matcher = pattern.matcher(resultOutputStream.toString("UTF-8"));
-        if (!matcher.find())
-        {
-            throw new RuntimeException("Failed to lookup the docker build ImageID.");
-        }
-
-        // find the last occurrence of "Successfully built"
-        String imageId;
-        do {
-            imageId = matcher.group(matcher.groupCount());
-        } while (matcher.find());
+        String imageId = tempImageIdFile.readToString();
 
         if (imageId.equals("")) {
-            throw new RuntimeException("Failed to lookup the docker build ImageID.");
+            throw new RuntimeException("Failed to lookup the docker build ImageID. ID cannot be empty.");
         }
+
+        listener.getLogger().println("ID of built image: \"" + imageId + "\"");
+        tempImageIdFile.delete();
+
         return imageId;
     }