Prototype OpenTelemetry Traces in MCP Server #274

swcollard · 2025-08-20T18:17:06Z

This change pulls in new crates and SDKs for instrumenting the Apollo MCP Server with Open Telemetry Traces. There is still plenty to work on so this PR is set up to merge into a long standing feature branch feature/telemetry.

Changes

Adds new rust crates to support OTel
Annotates excecute and call_tool functions with trace macro
Adds Axum and Tower middleware's for OTel tracing
Refactors Logging so that all the tracing_subscribers are set together in a single module.

Testing

Currently no unit testing since most tracing is happening through macros and there is not yet any configuration beyond the environment variables used within the SDKs.

I ran the all-in-one Jaegar container and started the mcp server with the following env vars

export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="http://127.0.0.1:4318/v1/traces"
export OTEL_EXPORTER_OTLP_TRACES_PROTOCOL="http/protobuf"
export OTEL_TRACES_SAMPLER="always_on"

This was able to produce traces such as...

apollo-librarian · 2025-08-20T18:17:14Z

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File Changes

0 new, 5 changed, 0 removed

* (developer-tools)/apollo-mcp-server/(latest)/index.mdx
* (developer-tools)/apollo-mcp-server/(latest)/install.mdx
* (developer-tools)/apollo-mcp-server/(latest)/limitations.mdx
* (developer-tools)/apollo-mcp-server/(latest)/guides/auth.mdx
* (developer-tools)/apollo-mcp-server/(latest)/_sidebar.yaml

Build ID: 567da6c89ab9259c96ee61f9
Build Logs: View logs

URL: https://www.apollographql.com/docs/deploy-preview/567da6c89ab9259c96ee61f9

github-actions · 2025-08-20T18:17:17Z

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github-actions · 2025-08-20T21:05:57Z

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Copilot

Pull Request Overview

This PR introduces OpenTelemetry tracing support to the Apollo MCP Server as a prototype feature. The changes enable distributed tracing by integrating OTel SDKs and instrumenting key operations with tracing capabilities.

Adds OpenTelemetry tracing infrastructure with proper initialization and shutdown handling
Instruments HTTP requests and GraphQL operations with trace spans
Refactors logging system to work alongside OpenTelemetry layers

Reviewed Changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Cargo.toml	Adds OpenTelemetry-related dependencies and enables tower-http trace features
src/main.rs	Replaces standalone logging setup with integrated tracing subscriber initialization
src/runtime.rs	Exposes new trace module
src/runtime/trace.rs	Implements OpenTelemetry tracer and meter provider initialization with proper cleanup
src/runtime/logging.rs	Refactors logging to return components for integration with OpenTelemetry layers
src/server/states/starting.rs	Adds Axum and Tower HTTP tracing middleware to the router
src/server/states/running.rs	Instruments ServerHandler methods with tracing macros
src/graphql.rs	Adds OpenTelemetry instrumentation to GraphQL client requests

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

Copilot · 2025-08-20T21:13:14Z

crates/apollo-mcp-server/src/runtime/trace.rs

+    let tracer_provider = init_tracer_provider()?;
+    let meter_provider = init_meter_provider()?;
+    let env_filter = Logging::env_filter(config)?;
+    let (logging_layer, logging_guard) = Logging::logging_layer(config)?;


The logging setup logic is split between this module and the Logging module, creating tight coupling. Consider consolidating all tracing setup logic in one place or making the dependency more explicit through better separation of concerns.

Suggested change

let (logging_layer, logging_guard) = Logging::logging_layer(config)?;

let env_filter = build_env_filter(config)?;

let (logging_layer, logging_guard) = build_logging_layer(config)?;

Copilot · 2025-08-20T21:13:14Z

crates/apollo-mcp-server/src/runtime/trace.rs

+        if let Err(err) = self.meter_provider.shutdown() {
+            eprintln!("{err:?}");
+        }
+        self.logging_guard.take();


Taking the logging_guard without dropping it explicitly may not properly clean up the logging worker. The guard should be allowed to drop naturally or explicitly dropped to ensure proper cleanup.

Suggested change

self.logging_guard.take();

drop(self.logging_guard.take());

crates/apollo-mcp-server/src/runtime/logging.rs

Copilot · 2025-08-20T21:13:15Z

crates/apollo-mcp-server/src/server/states/running.rs

@@ -180,6 +183,7 @@ impl ServerHandler for Running {
        Ok(self.get_info())
    }

+    #[tracing::instrument(skip(self, context), fields(tool_name = request.name.as_ref(), request_id = %context.id.clone()))]


The context.id.clone() in the tracing fields creates an unnecessary clone on every function call. Consider using a reference or moving the field extraction into the span creation to avoid the clone overhead.

Suggested change

#[tracing::instrument(skip(self, context), fields(tool_name = request.name.as_ref(), request_id = %context.id.clone()))]

#[tracing::instrument(skip(self, context), fields(tool_name = request.name.as_ref(), request_id = %context.id))]

crates/apollo-mcp-server/Cargo.toml

crates/apollo-mcp-server/src/runtime/trace.rs

crates/apollo-mcp-server/src/introspection/tools/introspect.rs

crates/apollo-mcp-server/src/runtime/logging.rs

crates/apollo-mcp-server/src/graphql.rs

Co-authored-by: Dale Seo <[email protected]>

DaleSeo

Thanks for addressing my feedback! 🙇

swcollard added 3 commits August 20, 2025 12:56

Create a prototype of otel emitting traces to local jaegar instance

9fb0c95

Add tracing annotations

967ef38

Combine logging and tracing

08f6dcf

swcollard requested a review from a team as a code owner August 20, 2025 18:17

swcollard requested review from Copilot and a team and removed request for a team August 20, 2025 18:17

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copilot feedback

9ce28d3

swcollard requested a review from Copilot August 20, 2025 21:11

Copilot AI reviewed Aug 20, 2025

View reviewed changes

swcollard added 3 commits August 21, 2025 09:46

Add changeset

7f2ee83

Instrument other tools

b0542bf

Clippy fixes

86a38e0

DaleSeo reviewed Aug 22, 2025

View reviewed changes

crates/apollo-mcp-server/src/runtime/trace.rs Show resolved Hide resolved

DaleSeo reviewed Aug 22, 2025

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crates/apollo-mcp-server/src/introspection/tools/introspect.rs Show resolved Hide resolved

crates/apollo-mcp-server/src/introspection/tools/introspect.rs Show resolved Hide resolved

DaleSeo reviewed Aug 22, 2025

View reviewed changes

swcollard and others added 3 commits August 22, 2025 14:21

PR feedback

b6166d2

Change default env name to development

ec0fef4

Co-authored-by: Dale Seo <[email protected]>

Remove some extraneous extensions

9478d0c

DaleSeo approved these changes Aug 22, 2025

View reviewed changes

swcollard merged commit 15f7008 into feature/telemetry Aug 25, 2025
8 checks passed

	let (logging_layer, logging_guard) = Logging::logging_layer(config)?;
	let env_filter = build_env_filter(config)?;
	let (logging_layer, logging_guard) = build_logging_layer(config)?;

	#[tracing::instrument(skip(self, context), fields(tool_name = request.name.as_ref(), request_id = %context.id.clone()))]
	#[tracing::instrument(skip(self, context), fields(tool_name = request.name.as_ref(), request_id = %context.id))]

Prototype OpenTelemetry Traces in MCP Server #274

Prototype OpenTelemetry Traces in MCP Server #274

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swcollard commented Aug 20, 2025

Changes

Testing

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Pull Request Overview

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