Resources

A resource represents the entity producing telemetry as resource attributes. For example, a process producing telemetry that is running in a container on Kubernetes has a process name, a pod name, a namespace, and possibly a deployment name. All four of these attributes can be included in the resource.

In your observability backend, you can use resource information to better investigate interesting behavior. For example, if your trace or metrics data indicate latency in your system, you can narrow it down to a specific container, pod, or Kubernetes deployment.

Resource Detection

The PHP SDK detects resources from a variety of sources, and by default will use all available resource detectors:

• environment (OTEL_RESOURCE_ATTRIBUTES, OTEL_SERVICE_NAME)
• host information
• host operating system
• current process
• runtime

Disabling resource detection

By default, all SDK resource detectors are used, but you can use the environment variable OTEL_PHP_RESOURCE_DETECTORS to enable only certain detectors, or completely disable them:

• env
• host
• os
• process
• process_runtime
• sdk
• sdk_provided
• all - enable all resource detectors
• none - disable resource detection

For example, to enable only the env, host and sdk detectors:

env OTEL_PHP_RESOURCE_DETECTORS=env,host,sdk \
php example.php

Custom resource detectors

Resource detectors for generic platforms or vendor-specific environments can be installed as composer packages.

For example, to install and enable the container resource detector:

composer require open-telemetry/detector-container
env OTEL_PHP_RESOURCE_DETECTORS=container \
php example.php

Note that installed detectors are automatically included in the default all resource detector list.

Adding resources with environment variables

If there is not an SDK detector for the resource you need, you can add arbitrary resources via the OTEL_RESOURCE_ATTRIBUTES environment variable, which is interpreted by the env detector. This variable takes a comma-separated list of key=value pairs, for example:

env OTEL_RESOURCE_ATTRIBUTES="service.name=my_service,service.namespace=demo,service.version=1.0,deployment.environment=development" \
php example.php

Adding resources in code

Custom resources can also be configured in your code. Here, the default resources (detected as described above) are merged with custom resources. The resources are then passed to the tracer provider, where they will be associated with all generated spans.

$resource = ResourceInfoFactory::defaultResource()->merge(ResourceInfo::create(Attributes::create([
    ResourceAttributes::SERVICE_NAMESPACE => 'foo',
    ResourceAttributes::SERVICE_NAME => 'bar',
    ResourceAttributes::SERVICE_INSTANCE_ID => 1,
    ResourceAttributes::SERVICE_VERSION => '0.1',
    ResourceAttributes::DEPLOYMENT_ENVIRONMENT_NAME => 'development',
])));

$tracerProvider =  new TracerProvider(
    new SimpleSpanProcessor(
        (new ConsoleSpanExporterFactory())->create()
    ),
    null,
    $resource
);