Add Git commit and build info metrics

.gitignore

@@ -1,4 +1,5 @@
 build/
+!micrometer-core/src/main/java/io/micrometer/core/instrument/binder/build
 .gradle/
 out/
 

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/MeterBinder.java

@@ -27,6 +27,8 @@
  */
 public interface MeterBinder {
 
+    String DEFAULT_TAG_VALUE = "unknown";
+
     void bindTo(@NonNull MeterRegistry registry);
 
 }

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/build/BuildInfo.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2023 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.micrometer.core.instrument.binder.build;
+
+import java.time.Instant;
+import java.util.Optional;
+
+public class BuildInfo {
+
+    private final String group;
+
+    private final String artifact;
+
+    private final String name;
+
+    private final String version;
+
+    private final Instant timestamp;
+
+    private BuildInfo(String group, String artifact, String name, String version, Instant timestamp) {
+        this.group = group;
+        this.artifact = artifact;
+        this.name = name;
+        this.version = version;
+        this.timestamp = timestamp;
+    }
+
+    public static BuildInfo.Builder builder() {
+        return new BuildInfo.Builder();
+    }
+
+    public Optional<String> getGroup() {
+        return Optional.ofNullable(group);
+    }
+
+    public Optional<String> getArtifact() {
+        return Optional.ofNullable(artifact);
+    }
+
+    public Optional<String> getName() {
+        return Optional.ofNullable(name);
+    }
+
+    public Optional<String> getVersion() {
+        return Optional.ofNullable(version);
+    }
+
+    public Optional<Instant> getTimestamp() {
+        return Optional.ofNullable(timestamp);
+    }
+
+    public static class Builder {
+
+        private String group;
+
+        private String artifact;
+
+        private String name;
+
+        private String version;
+
+        private Instant timestamp;
+
+        private Builder() {
+        }
+
+        public BuildInfo build() {
+            return new BuildInfo(group, artifact, name, version, timestamp);
+        }
+
+        public Builder group(String group) {
+            this.group = group;
+            return this;
+        }
+
+        public Builder artifact(String artifact) {
+            this.artifact = artifact;
+            return this;
+        }
+
+        public Builder name(String name) {
+            this.name = name;
+            return this;
+        }
+
+        public Builder version(String version) {
+            this.version = version;
+            return this;
+        }
+
+        public Builder timestamp(Instant timestamp) {
+            this.timestamp = timestamp;
+            return this;
+        }
+
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/build/BuildInfoMetrics.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2023 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.micrometer.core.instrument.binder.build;
+
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.binder.MeterBinder;
+
+import java.time.Instant;
+
+import static java.util.Objects.requireNonNull;
+
+public class BuildInfoMetrics implements MeterBinder {
+
+    private final BuildInfo buildInfo;
+
+    public BuildInfoMetrics(BuildInfo buildInfo) {
+        requireNonNull(buildInfo, "buildInfo");
+        this.buildInfo = buildInfo;
+    }
+
+    @Override
+    public void bindTo(MeterRegistry registry) {
+        requireNonNull(registry, "registry");
+        Gauge.builder("build.info", () -> 1L)
+            .description("Build information")
+            .strongReference(true)
+            .tag("group", buildInfo.getGroup().orElse(DEFAULT_TAG_VALUE))
+            .tag("artifact", buildInfo.getArtifact().orElse(DEFAULT_TAG_VALUE))
+            .tag("name", buildInfo.getName().orElse(DEFAULT_TAG_VALUE))
+            .tag("version", buildInfo.getVersion().orElse(DEFAULT_TAG_VALUE))
+            .tag("timestamp", buildInfo.getTimestamp().map(Instant::toString).orElse(DEFAULT_TAG_VALUE))
+            .register(registry);
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/build/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2023 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Meter binders for build info.
+ */
+package io.micrometer.core.instrument.binder.build;

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/git/GitCommitInfo.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2023 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.micrometer.core.instrument.binder.git;
+
+import java.time.Instant;
+import java.util.Optional;
+
+/**
+ * Information from a Git commit.
+ */
+public class GitCommitInfo {
+
+    private final String branch;
+
+    private final String commitId;
+
+    private final String commitIdShort;
+
+    private final Instant commitTime;
+
+    private GitCommitInfo(String branch, String commitId, String commitIdShort, Instant commitTime) {
+        this.branch = branch;
+        this.commitId = commitId;
+        this.commitIdShort = commitIdShort;
+        this.commitTime = commitTime;
+    }
+
+    public static GitCommitInfo.Builder builder() {
+        return new GitCommitInfo.Builder();
+    }
+
+    public Optional<String> getBranch() {
+        return Optional.ofNullable(branch);
+    }
+
+    public Optional<String> getCommitId() {
+        return Optional.ofNullable(commitId);
+    }
+
+    public Optional<String> getShortCommitId() {
+        return Optional.ofNullable(commitIdShort);
+    }
+
+    public Optional<Instant> getCommitTime() {
+        return Optional.ofNullable(commitTime);
+    }
+
+    public static class Builder {
+
+        private String branch;
+
+        private String commitId;
+
+        private String commitIdShort;
+
+        private Instant commitTime;
+
+        private Builder() {
+        }
+
+        public GitCommitInfo build() {
+            return new GitCommitInfo(branch, commitId, commitIdShort, commitTime);
+        }
+
+        public Builder branch(String branch) {
+            this.branch = branch;
+            return this;
+        }
+
+        public Builder commitId(String commitId) {
+            this.commitId = commitId;
+            return this;
+        }
+
+        public Builder commitIdShort(String commitIdShort) {
+            this.commitIdShort = commitIdShort;
+            return this;
+        }
+
+        public Builder commitTime(Instant commitTime) {
+            this.commitTime = commitTime;
+            return this;
+        }
+
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/git/GitCommitInfoMetrics.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2023 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.micrometer.core.instrument.binder.git;
+
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.binder.MeterBinder;
+
+import java.time.Instant;
+
+import static java.util.Objects.requireNonNull;
+
+public class GitCommitInfoMetrics implements MeterBinder {
+
+    private final GitCommitInfo gitCommitInfo;
+
+    public GitCommitInfoMetrics(GitCommitInfo gitCommitInfo) {
+        requireNonNull(gitCommitInfo, "gitCommitInfo");
+        this.gitCommitInfo = gitCommitInfo;
+    }
+
+    @Override
+    public void bindTo(MeterRegistry registry) {
+        requireNonNull(registry, "registry");
+        Gauge.builder("git.commit.info", () -> 1L)
+            .description("Git commit information")
+            .strongReference(true)
+            .tag("branch", gitCommitInfo.getBranch().orElse(DEFAULT_TAG_VALUE))
+            .tag("commit.id", gitCommitInfo.getCommitId().orElse(DEFAULT_TAG_VALUE))
+            .tag("commit.id.short", gitCommitInfo.getShortCommitId().orElse(DEFAULT_TAG_VALUE))
+            .tag("commit.timestamp", gitCommitInfo.getCommitTime().map(Instant::toString).orElse(DEFAULT_TAG_VALUE))
+            .register(registry);
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/git/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2023 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Meter binders for git info.
+ */
+package io.micrometer.core.instrument.binder.git;