Instrument Applications

Application instrumentation is the process of adding observability signals - traces, metrics, and logs - to your application code. The OpenSearch Observability Stack uses OpenTelemetry (OTel) as its standard instrumentation framework, giving you a vendor-neutral way to collect telemetry from any language.

How it works

Your application uses an OpenTelemetry SDK to generate telemetry data and export it to the OTel Collector running alongside your stack:

Application (OTel SDK) → OTel Collector (localhost:4317/4318) → Data Prepper → OpenSearch

The Collector accepts data over two protocols:

Protocol	Port	Use case
gRPC	`4317`	Server-side applications (recommended)
HTTP/protobuf	`4318`	Browser apps, environments where gRPC is unavailable

Auto vs. manual instrumentation

OpenTelemetry offers two approaches to instrumenting your code:

Auto-instrumentation

Auto-instrumentation uses agents or require hooks to automatically capture telemetry from popular frameworks and libraries without code changes. This is the fastest way to get started.

Best for: Getting broad coverage quickly, standard web frameworks, database clients, HTTP libraries.

Available for: Python, Node.js, Java, .NET, Ruby, PHP.

Manual instrumentation

Manual instrumentation gives you full control over what gets traced and measured. You create spans, record metrics, and emit logs explicitly in your code.

Best for: Custom business logic, AI/ML pipelines, agent workflows, fine-grained control.

Available for: All languages with an OpenTelemetry SDK.

Combining both

Most production applications use both approaches together - auto-instrumentation for framework-level coverage and manual instrumentation for business-specific observability.

Common environment variables

All OpenTelemetry SDKs respect a standard set of environment variables. You can configure instrumentation without code changes by setting these:

Variable	Description	Default
`OTEL_SERVICE_NAME`	Logical name of your service	`unknown_service`
`OTEL_EXPORTER_OTLP_ENDPOINT`	Collector endpoint URL	`http://localhost:4317` (gRPC)
`OTEL_EXPORTER_OTLP_PROTOCOL`	Export protocol (`grpc`, `http/protobuf`)	`grpc`
`OTEL_TRACES_EXPORTER`	Traces exporter (`otlp`, `none`)	`otlp`
`OTEL_METRICS_EXPORTER`	Metrics exporter (`otlp`, `none`)	`otlp`
`OTEL_LOGS_EXPORTER`	Logs exporter (`otlp`, `none`)	`otlp`
`OTEL_RESOURCE_ATTRIBUTES`	Comma-separated key=value resource attributes	-
`OTEL_TRACES_SAMPLER`	Sampler type (`always_on`, `traceidratio`, `parentbased_traceidratio`)	`parentbased_always_on`
`OTEL_TRACES_SAMPLER_ARG`	Sampler argument (e.g., ratio `0.1`)	-
`OTEL_PROPAGATORS`	Context propagation formats	`tracecontext,baggage`

Example using environment variables:

export OTEL_SERVICE_NAME="my-service"
export OTEL_EXPORTER_OTLP_ENDPOINT="http://localhost:4317"
export OTEL_RESOURCE_ATTRIBUTES="deployment.environment=production,service.version=2.1.0"

Resource attributes

Every telemetry signal includes resource attributes that identify the source. At minimum, set these:

Attribute	Description	Example
`service.name`	Name of the service	`checkout-service`
`service.version`	Version of the service	`1.2.3`
`deployment.environment`	Deployment environment	`production`

Supported languages

Choose your language to get started:

Language	Auto-instrumentation	Page	Upstream Docs
Python	Yes	Python	OTel Python
Node.js	Yes	Node.js	OTel JS
Java	Yes	Java	OTel Java
Go	No (use middleware)	Go	OTel Go
.NET	Yes	.NET	OTel .NET
Ruby	Yes	Ruby	OTel Ruby
Browser / Frontend	Partial	Browser	OTel JS

OpenTelemetry overview
Auto-instrumentation
Manual instrumentation
OTel Collector configuration
OpenTelemetry Language APIs & SDKs — All supported languages and instrumentation guides