#3308 Support adding container.id to resource metadata (#3321)

* Support adding container.id to resource metadta

* Address review comments

* Address review feedback

* Change containerResource to cached Resource factory

* Make method private

* Change to Paths and Files

* Fix bad merge and change regex

* Remove debug code, remove regex

* Add nullable annotation

Co-authored-by: Anuraag Agrawal <aanuraag@amazon.co.jp>

docs/apidiffs/current_vs_latest/opentelemetry-sdk-extension-resources.txt

@@ -1,2 +1,10 @@
 Comparing source compatibility of  against 
-No changes.
++++  NEW CLASS: PUBLIC(+) FINAL(+) io.opentelemetry.sdk.extension.resources.ContainerResource  (not serializable)
+	+++  CLASS FILE FORMAT VERSION: 52.0 <- n.a.
+	+++  NEW SUPERCLASS: java.lang.Object
+	+++  NEW METHOD: PUBLIC(+) STATIC(+) io.opentelemetry.sdk.resources.Resource get()
++++  NEW CLASS: PUBLIC(+) io.opentelemetry.sdk.extension.resources.ContainerResourceProvider  (not serializable)
+	+++  CLASS FILE FORMAT VERSION: 52.0 <- n.a.
+	+++  NEW SUPERCLASS: java.lang.Object
+	+++  NEW CONSTRUCTOR: PUBLIC(+) ContainerResourceProvider()
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.sdk.resources.Resource createResource(io.opentelemetry.sdk.autoconfigure.ConfigProperties)

sdk-extensions/resources/src/main/java/io/opentelemetry/sdk/extension/resources/ContainerResource.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.resources;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.internal.OtelEncodingUtils;
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.stream.Stream;
+import javax.annotation.Nullable;
+import org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement;
+
+/** Factory for {@link Resource} retrieving Container ID information. */
+public final class ContainerResource {
+
+  private static final Logger logger = Logger.getLogger(ContainerResource.class.getName());
+  private static final String UNIQUE_HOST_NAME_FILE_NAME = "/proc/self/cgroup";
+  private static final Resource INSTANCE = buildSingleton(UNIQUE_HOST_NAME_FILE_NAME);
+
+  @IgnoreJRERequirement
+  private static Resource buildSingleton(String uniqueHostNameFileName) {
+    // can't initialize this statically without running afoul of animalSniffer on paths
+    return buildResource(Paths.get(uniqueHostNameFileName));
+  }
+
+  // package private for testing
+  static Resource buildResource(Path path) {
+    String containerId = extractContainerId(path);
+
+    if (containerId == null || containerId.isEmpty()) {
+      return Resource.empty();
+    } else {
+      return Resource.create(Attributes.of(ResourceAttributes.CONTAINER_ID, containerId));
+    }
+  }
+
+  /** Returns resource with container information. */
+  public static Resource get() {
+    return INSTANCE;
+  }
+
+  /**
+   * Each line of cgroup file looks like "14:name=systemd:/docker/.../... A hex string is expected
+   * inside the last section separated by '/' Each segment of the '/' can contain metadata separated
+   * by either '.' (at beginning) or '-' (at end)
+   *
+   * @return containerId
+   */
+  @IgnoreJRERequirement
+  @Nullable
+  private static String extractContainerId(Path cgroupFilePath) {
+    if (!Files.exists(cgroupFilePath) || !Files.isReadable(cgroupFilePath)) {
+      return null;
+    }
+    try (Stream<String> lines = Files.lines(cgroupFilePath)) {
+      Optional<String> value =
+          lines
+              .filter(line -> !line.isEmpty())
+              .map(line -> getIdFromLine(line))
+              .filter(Objects::nonNull)
+              .findFirst();
+      if (value.isPresent()) {
+        return value.get();
+      }
+    } catch (IOException e) {
+      logger.log(Level.WARNING, "Unable to read file: " + e.getMessage());
+    }
+    return null;
+  }
+
+  @Nullable
+  private static String getIdFromLine(String line) {
+    // This cgroup output line should have the container id in it
+    int lastSlashIdx = line.lastIndexOf("/");
+    if (lastSlashIdx < 0) {
+      return null;
+    }
+
+    String lastSection = line.substring(lastSlashIdx + 1);
+    int startIdx = lastSection.indexOf("-");
+    int endIdx = lastSection.lastIndexOf(".");
+
+    String containerId =
+        lastSection.substring(
+            startIdx == -1 ? 0 : startIdx + 1, endIdx == -1 ? lastSection.length() : endIdx);
+    if (OtelEncodingUtils.isValidBase16String(containerId) && !containerId.isEmpty()) {
+      return containerId;
+    } else {
+      return null;
+    }
+  }
+
+  private ContainerResource() {}
+}

sdk-extensions/resources/src/main/java/io/opentelemetry/sdk/extension/resources/ContainerResourceProvider.java

@@ -0,0 +1,18 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.resources;
+
+import io.opentelemetry.sdk.autoconfigure.ConfigProperties;
+import io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider;
+import io.opentelemetry.sdk.resources.Resource;
+
+/** {@link ResourceProvider} for automatically configuring {@link ResourceProvider}. */
+public class ContainerResourceProvider implements ResourceProvider {
+  @Override
+  public Resource createResource(ConfigProperties config) {
+    return ContainerResource.get();
+  }
+}

sdk-extensions/resources/src/main/resources/META-INF/services/io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider

@@ -1,3 +1,4 @@
+io.opentelemetry.sdk.extension.resources.ContainerResourceProvider
 io.opentelemetry.sdk.extension.resources.HostResourceProvider
 io.opentelemetry.sdk.extension.resources.OsResourceProvider
 io.opentelemetry.sdk.extension.resources.ProcessResourceProvider

sdk-extensions/resources/src/test/java/io/opentelemetry/sdk/extension/resources/ContainerResourceTest.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.resources;
+
+import static io.opentelemetry.sdk.extension.resources.ContainerResource.buildResource;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+public class ContainerResourceTest {
+
+  // Invalid because ID is not a hex string
+  private static final String INVALID_CGROUP_LINE_1 =
+      "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23zzzz";
+
+  // with suffix
+  private static final String CGROUP_LINE_1 =
+      "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23.aaaa";
+  private static final String EXPECTED_CGROUP_1 = "ac679f8a8319c8cf7d38e1adf263bc08d23";
+
+  // with prefix and suffix
+  private static final String CGROUP_LINE_2 =
+      "13:name=systemd:/podruntime/docker/kubepods/crio-dc679f8a8319c8cf7d38e1adf263bc08d23.stuff";
+  private static final String EXPECTED_CGROUP_2 = "dc679f8a8319c8cf7d38e1adf263bc08d23";
+
+  // just container id
+  private static final String CGROUP_LINE_3 =
+      "13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356";
+  private static final String EXPECTED_CGROUP_3 =
+      "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356";
+
+  // with prefix
+  private static final String CGROUP_LINE_4 =
+      "//\n"
+          + "1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23"
+          + "2:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23"
+          + "3:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23";
+
+  private static final String EXPECTED_CGROUP_4 = "dc579f8a8319c8cf7d38e1adf263bc08d23";
+
+  @Test
+  public void testNegativeCases(@TempDir Path tempFolder) throws IOException {
+    // invalid containerId (non-hex)
+    Path cgroup = createCGroup(tempFolder.resolve("cgroup1"), INVALID_CGROUP_LINE_1);
+    assertThat(buildResource(cgroup)).isEqualTo(Resource.empty());
+
+    // test invalid file
+    cgroup = tempFolder.resolve("DoesNotExist");
+    assertThat(buildResource(cgroup)).isEqualTo(Resource.empty());
+  }
+
+  @Test
+  public void testContainer(@TempDir Path tempFolder) throws IOException {
+    Path cgroup = createCGroup(tempFolder.resolve("cgroup1"), CGROUP_LINE_1);
+    assertThat(getContainerId(buildResource(cgroup))).isEqualTo(EXPECTED_CGROUP_1);
+
+    Path cgroup2 = createCGroup(tempFolder.resolve("cgroup2"), CGROUP_LINE_2);
+    assertThat(getContainerId(buildResource(cgroup2))).isEqualTo(EXPECTED_CGROUP_2);
+
+    Path cgroup3 = createCGroup(tempFolder.resolve("cgroup3"), CGROUP_LINE_3);
+    assertThat(getContainerId(buildResource(cgroup3))).isEqualTo(EXPECTED_CGROUP_3);
+
+    Path cgroup4 = createCGroup(tempFolder.resolve("cgroup4"), CGROUP_LINE_4);
+    assertThat(getContainerId(buildResource(cgroup4))).isEqualTo(EXPECTED_CGROUP_4);
+  }
+
+  private static String getContainerId(Resource resource) {
+    return resource.getAttributes().get(ResourceAttributes.CONTAINER_ID);
+  }
+
+  private static Path createCGroup(Path path, String line) throws IOException {
+    return Files.write(path, line.getBytes(StandardCharsets.UTF_8));
+  }
+}