Make git revision loading lazy (#45358)

This commit makes the gitRevision property a lazy loaded value by
returning an Object implementing toString(). The Dockerfile template is
also changed to use groovy templates instead of the mavenfilter hack, so
converting to String will not happen until runtime.

buildSrc/src/main/java/org/elasticsearch/gradle/info/GlobalBuildInfoPlugin.java

@@ -23,6 +23,7 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -45,6 +46,8 @@ public class GlobalBuildInfoPlugin implements Plugin<Project> {
         File compilerJavaHome = findCompilerJavaHome();
         File runtimeJavaHome = findRuntimeJavaHome(compilerJavaHome);
 
+        Object gitRevisionResolver = createGitRevisionResolver(project);
+
         final List<JavaHome> javaVersions = new ArrayList<>();
         for (int version = 8; version <= Integer.parseInt(minimumCompilerVersion.getMajorVersion()); version++) {
             if (System.getenv(getJavaHomeEnvVarName(Integer.toString(version))) != null) {
@@ -92,7 +95,7 @@ public class GlobalBuildInfoPlugin implements Plugin<Project> {
             ext.set("minimumCompilerVersion", minimumCompilerVersion);
             ext.set("minimumRuntimeVersion", minimumRuntimeVersion);
             ext.set("gradleJavaVersion", Jvm.current().getJavaVersion());
-            ext.set("gitRevision", gitRevision(project));
+            ext.set("gitRevision", gitRevisionResolver);
             ext.set("buildDate", ZonedDateTime.now(ZoneOffset.UTC));
         });
     }
@@ -203,21 +206,35 @@ public class GlobalBuildInfoPlugin implements Plugin<Project> {
         return _defaultParallel;
     }
 
-    private String gitRevision(final Project project) {
-        final ByteArrayOutputStream stdout = new ByteArrayOutputStream();
-        final ByteArrayOutputStream stderr = new ByteArrayOutputStream();
-        final ExecResult result = project.exec(spec -> {
-            spec.setExecutable("git");
-            spec.setArgs(Arrays.asList("rev-parse", "HEAD"));
-            spec.setStandardOutput(stdout);
-            spec.setErrorOutput(stderr);
-            spec.setIgnoreExitValue(true);
-        });
+    private Object createGitRevisionResolver(final Project project) {
+        return new Object() {
+            private final AtomicReference<String> gitRevision = new AtomicReference<>();
+
+            @Override
+            public String toString() {
+                if (gitRevision.get() == null) {
+                    final ByteArrayOutputStream stdout = new ByteArrayOutputStream();
+                    final ByteArrayOutputStream stderr = new ByteArrayOutputStream();
+                    final ExecResult result = project.exec(spec -> {
+                        spec.setExecutable("git");
+                        spec.setArgs(Arrays.asList("rev-parse", "HEAD"));
+                        spec.setStandardOutput(stdout);
+                        spec.setErrorOutput(stderr);
+                        spec.setIgnoreExitValue(true);
+                    });
+
+                    final String revision;
+                    if (result.getExitValue() != 0) {
+                        revision = "unknown";
+                    } else {
+                        revision = stdout.toString(UTF_8).trim();
+                    }
+                    this.gitRevision.compareAndSet(null, revision);
+                }
+                return gitRevision.get();
+            }
+        };
 
-        if (result.getExitValue() != 0) {
-            return "unknown";
-        }
-        return stdout.toString(UTF_8).trim();
     }
 
 }

distribution/docker/build.gradle

@@ -1,6 +1,5 @@
 import org.elasticsearch.gradle.BuildPlugin
 import org.elasticsearch.gradle.LoggedExec
-import org.elasticsearch.gradle.MavenFilteringHack
 import org.elasticsearch.gradle.VersionProperties
 import org.elasticsearch.gradle.testfixtures.TestFixturesPlugin 
 
@@ -58,7 +57,7 @@ project.ext {
       }
 
       from(project.projectDir.toPath().resolve("src/docker/Dockerfile")) {
-        MavenFilteringHack.filter(it, expansions(oss, local))
+        expand(expansions(oss, local))
       }
     }
   }
@@ -66,7 +65,9 @@ project.ext {
 
 void addCopyDockerContextTask(final boolean oss) {
   task(taskName("copy", oss, "DockerContext"), type: Sync) {
-    inputs.properties(expansions(oss, true))
+    expansions(oss, true).each { k, v ->
+      inputs.property(k, { v.toString() })
+    }
     into files(oss)
 
     with dockerBuildContext(oss, true)

distribution/docker/src/docker/Dockerfile

@@ -13,7 +13,7 @@
 
 FROM centos:7 AS builder
 
-ENV PATH /usr/share/elasticsearch/bin:$PATH
+ENV PATH /usr/share/elasticsearch/bin:\$PATH
 
 RUN groupadd -g 1000 elasticsearch && \
     adduser -u 1000 -g 1000 -d /usr/share/elasticsearch elasticsearch
@@ -41,8 +41,8 @@ ENV ELASTIC_CONTAINER true
 
 RUN for iter in {1..10}; do yum update -y && \
     yum install -y nc && \
-    yum clean all && exit_code=0 && break || exit_code=$? && echo "yum error: retry $iter in 10s" && sleep 10; done; \
-    (exit $exit_code)
+    yum clean all && exit_code=0 && break || exit_code=\$? && echo "yum error: retry \$iter in 10s" && sleep 10; done; \
+    (exit \$exit_code)
 
 RUN groupadd -g 1000 elasticsearch && \
     adduser -u 1000 -g 1000 -G 0 -d /usr/share/elasticsearch elasticsearch && \
@@ -57,7 +57,7 @@ COPY --from=builder --chown=1000:0 /usr/share/elasticsearch /usr/share/elasticse
 # REF: https://github.com/elastic/elasticsearch-docker/issues/171
 RUN ln -sf /etc/pki/ca-trust/extracted/java/cacerts /usr/share/elasticsearch/jdk/lib/security/cacerts
 
-ENV PATH /usr/share/elasticsearch/bin:$PATH
+ENV PATH /usr/share/elasticsearch/bin:\$PATH
 
 COPY --chown=1000:0 bin/docker-entrypoint.sh /usr/local/bin/docker-entrypoint.sh