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feat(lambda): read cloud.account.id from symlink in Lambda detector #2619

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4a7f154
feat(aws-resources): read cloud.account.id from symlink in Lambda det…
RaphaelManke Feb 9, 2026
0163695
fix: replace Path.of() with Paths.get() for Java 8 compatibility
RaphaelManke Feb 9, 2026
429ed6a
docs: add CHANGELOG entry for cloud.account.id symlink feature
RaphaelManke Feb 11, 2026
7810e9d
Rename symlink to .otel-aws-account-id
RaphaelManke Feb 18, 2026
323b0e4
Add debug log when cloud.account.id symlink is not available
RaphaelManke Feb 18, 2026
71420bf
style: use static import for Level.FINE in LambdaResource
RaphaelManke Feb 19, 2026
4679a6d
Merge branch 'main' into feat/cloud-account-id-symlink
laurit Mar 10, 2026
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5 changes: 5 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,11 @@

## Unreleased

### AWS Lambda resource detector

- Read `cloud.account.id` from symlink created by the OTel Lambda Extension
([#2619](https://github.com/open-telemetry/opentelemetry-java-contrib/pull/2619))

## Version 1.54.0 (2026-02-18)

### Compressors
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27 changes: 26 additions & 1 deletion aws-resources/src/main/java/io/opentelemetry/contrib/aws/resource/LambdaResource.java
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Expand Up @@ -5,24 +5,35 @@

package io.opentelemetry.contrib.aws.resource;

import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.CLOUD_ACCOUNT_ID;
import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.CLOUD_PLATFORM;
import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.CLOUD_PROVIDER;
import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.CLOUD_REGION;
import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.CloudPlatformIncubatingValues.AWS_LAMBDA;
import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.CloudProviderIncubatingValues.AWS;
import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.FAAS_NAME;
import static io.opentelemetry.contrib.aws.resource.IncubatingAttributes.FAAS_VERSION;
import static java.util.logging.Level.FINE;

import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.api.common.AttributesBuilder;
import io.opentelemetry.sdk.resources.Resource;
import io.opentelemetry.semconv.SchemaUrls;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Map;
import java.util.logging.Logger;
import java.util.stream.Stream;

/** A factory for a {@link Resource} which provides information about the AWS Lambda function. */
public final class LambdaResource {

private static final Logger logger = Logger.getLogger(LambdaResource.class.getName());

private static final String ACCOUNT_ID_SYMLINK_PATH = "/tmp/.otel-aws-account-id";

private static final Resource INSTANCE = buildResource();

/**
Expand All @@ -34,11 +45,16 @@ public static Resource get() {
}

private static Resource buildResource() {
return buildResource(System.getenv());
return buildResource(System.getenv(), Paths.get(ACCOUNT_ID_SYMLINK_PATH));
}

// Visible for testing
static Resource buildResource(Map<String, String> environmentVariables) {
return buildResource(environmentVariables, Paths.get(ACCOUNT_ID_SYMLINK_PATH));
}

// Visible for testing
static Resource buildResource(Map<String, String> environmentVariables, Path accountIdSymlink) {
String region = environmentVariables.getOrDefault("AWS_REGION", "");
String functionName = environmentVariables.getOrDefault("AWS_LAMBDA_FUNCTION_NAME", "");
String functionVersion = environmentVariables.getOrDefault("AWS_LAMBDA_FUNCTION_VERSION", "");
Expand All @@ -60,6 +76,15 @@ static Resource buildResource(Map<String, String> environmentVariables) {
builder.put(FAAS_VERSION, functionVersion);
}

try {
String accountId = Files.readSymbolicLink(accountIdSymlink).toString();
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@laurit laurit Mar 10, 2026

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you could check with Files.isSymbolicLink to avoid triggering exceptions when the file does not exist

if (!accountId.isEmpty()) {
builder.put(CLOUD_ACCOUNT_ID, accountId);
}
} catch (IOException | UnsupportedOperationException e) {
logger.log(FINE, "cloud.account.id not available via symlink", e);
}

return Resource.create(builder.build(), SchemaUrls.V1_25_0);
}

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52 changes: 52 additions & 0 deletions aws-resources/src/test/java/io/opentelemetry/contrib/aws/resource/LambdaResourceTest.java
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Expand Up @@ -6,6 +6,7 @@
package io.opentelemetry.contrib.aws.resource;

import static io.opentelemetry.sdk.testing.assertj.OpenTelemetryAssertions.assertThat;
import static io.opentelemetry.semconv.incubating.CloudIncubatingAttributes.CLOUD_ACCOUNT_ID;
import static io.opentelemetry.semconv.incubating.CloudIncubatingAttributes.CLOUD_PLATFORM;
import static io.opentelemetry.semconv.incubating.CloudIncubatingAttributes.CLOUD_PROVIDER;
import static io.opentelemetry.semconv.incubating.CloudIncubatingAttributes.CLOUD_REGION;
Expand All @@ -19,10 +20,14 @@
import io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider;
import io.opentelemetry.sdk.resources.Resource;
import io.opentelemetry.semconv.SchemaUrls;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.Map;
import java.util.ServiceLoader;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.io.TempDir;

class LambdaResourceTest {
@Test
Expand Down Expand Up @@ -65,6 +70,53 @@ void shouldAddAllAttributes() {
entry(FAAS_VERSION, "1.2.3"));
}

@Test
void shouldReadCloudAccountIdFromSymlink(@TempDir Path tempDir) throws Exception {
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@laurit laurit Mar 10, 2026

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it would be nice to skip the test when run on windows

Path symlink = tempDir.resolve(".otel-aws-account-id");
Files.createSymbolicLink(symlink, Paths.get("123456789012"));

Resource resource =
LambdaResource.buildResource(
singletonMap("AWS_LAMBDA_FUNCTION_NAME", "my-function"), symlink);
Attributes attributes = resource.getAttributes();

assertThat(attributes)
.containsOnly(
entry(CLOUD_PROVIDER, "aws"),
entry(CLOUD_PLATFORM, "aws_lambda"),
entry(FAAS_NAME, "my-function"),
entry(CLOUD_ACCOUNT_ID, "123456789012"));
}

@Test
void shouldSkipCloudAccountIdWhenSymlinkMissing(@TempDir Path tempDir) {
Path symlink = tempDir.resolve(".otel-aws-account-id");

Resource resource =
LambdaResource.buildResource(
singletonMap("AWS_LAMBDA_FUNCTION_NAME", "my-function"), symlink);
Attributes attributes = resource.getAttributes();

assertThat(attributes)
.containsOnly(
entry(CLOUD_PROVIDER, "aws"),
entry(CLOUD_PLATFORM, "aws_lambda"),
entry(FAAS_NAME, "my-function"));
}

@Test
void shouldPreserveLeadingZerosInAccountId(@TempDir Path tempDir) throws Exception {
Path symlink = tempDir.resolve(".otel-aws-account-id");
Files.createSymbolicLink(symlink, Paths.get("012345678901"));

Resource resource =
LambdaResource.buildResource(
singletonMap("AWS_LAMBDA_FUNCTION_NAME", "my-function"), symlink);
Attributes attributes = resource.getAttributes();

assertThat(attributes).containsEntry(CLOUD_ACCOUNT_ID, "012345678901");
}

@Test
void inServiceLoader() {
// No practical way to test the attributes themselves so at least check the service loader picks
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