Add Windows Named Pipes to Dogstatsd #59

Lewis-E · 2025-12-26T17:30:15Z

What does this PR do?

Adds a NamedPipe BufferReader option to let Dogstatsd use windows specific functionality
Adopts the multi-instance approach used by winio and the main agent: one server instance per client, spawned in separate tasks.
Uses DD_DOGSTATSD_WINDOWS_PIPE_NAME for config + DD_DOGSTATSD_PORT is overridden to 0 when pipe name is set
The issue of multiple functions is NOT solved by this PR. We need to add a uniqueness factor to the envvar to handle multiple functions in the same plan, similar to the AAS extension GUID usage, but this needs to be handled 1) at the compat layer so it can be distributed to the rust mini-agent and the dogstatsd library from a single source of truth, and 2) we can't modify envvars in java, so we will also need to add another communication method to dogstatsd java envvar handling.

Motivation

When multiple functions run in Windows run on the same plan, only one can connect due to port conflicts for trace agent and dogstatsd agent. The Serverless Compatibility Layer should use named pipes in Windows for transport to prevent this issue.

Additional Notes

See also: Add Windows Named Pipes to the Trace Agent #58

Describe how to test/QA your changes

New #[cfg(test)] in integration_tests.rs
Manual testing in Azure

Separate ticket to add this to self-monitoring when the multiple functions functionality is added: https://datadoghq.atlassian.net/browse/SVLS-8248

Lewis-E · 2025-12-29T19:45:40Z

crates/dogstatsd/src/dogstatsd.rs

 enum BufferReader {
-    UdpSocketReader(tokio::net::UdpSocket),
+    /// UDP socket reader (cross-platform, default transport)
+    UdpSocket(tokio::net::UdpSocket),


Clippy change to remove consistent suffix. (All buffer readers are readers.)

duncanpharvey · 2026-01-20T20:33:49Z

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chatgpt-codex-connector · 2026-01-20T20:39:59Z

crates/datadog-trace-agent/src/mini_agent.rs

+        let mut config_json = serde_json::json!({
+            "statsd_port": dd_dogstatsd_port
+        });


Report no UDP port when named pipe is configured

When DD_DOGSTATSD_WINDOWS_PIPE_NAME is set on Windows, datadog-serverless-compat normalizes the pipe name and disables UDP by forcing the listener port to 0, but Config::new still reads DD_DOGSTATSD_PORT (default 8125) and this /info response always emits statsd_port from that value. In that setup, tracers that only consult statsd_port will try UDP even though no UDP socket is bound, so metrics will be dropped. Consider mirroring the server behavior by setting the port to 0 (or omitting statsd_port) when a pipe name is present so /info reflects the actual transport.

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duncanpharvey · 2026-01-20T21:06:46Z

crates/datadog-trace-agent/src/mini_agent.rs

+        });
+
+        if let Some(pipe_name) = dd_dogstatsd_windows_pipe_name {
+            config_json["statsd_windows_pipe_name"] = serde_json::json!(pipe_name);


I checked the /info response in a Windows environment for a non-Serverless agent and statsd_windows_pipe_name is not set. The named pipe is not included in the response.

duncanpharvey · 2026-01-20T21:18:51Z

crates/dogstatsd/src/dogstatsd.rs

+        }
+
+        // Create new named pipe server
+        let server = match ServerOptions::new().create(&*pipe_name) {


Did you run into any permission issues when opening the named pipe? It would be good to understand what the default security descriptor is and if we should set a different value to match what's done in the non Serverless agent.

https://github.com/DataDog/datadog-agent/blob/818a050bff727bd07e3e4ce93787b6537014e828/pkg/trace/config/config.go#L615

See https://datadoghq.atlassian.net/browse/SVLS-8192 for additional context

jcstorms1

Same as #58. Logic looks good, but I'll defer more technical comments to those with more expertise.

…improvements

Lewis-E · 2026-02-02T16:32:03Z

crates/datadog-serverless-compat/src/main.rs


 const DOGSTATSD_FLUSH_INTERVAL: u64 = 10;
 const DOGSTATSD_TIMEOUT_DURATION: Duration = Duration::from_secs(5);
-const DEFAULT_DOGSTATSD_PORT: u16 = 8125;


Moved into config

Going to undo this, actually. Separation of concerns for trace/dogstatsd

Lewis-E force-pushed the lewis/SVLS-6029/dogstatsd-named-pipes branch 17 times, most recently from 6d4e402 to f97a7e0 Compare December 29, 2025 19:44

Lewis-E commented Dec 29, 2025

View reviewed changes

Lewis-E force-pushed the lewis/SVLS-6029/dogstatsd-named-pipes branch 12 times, most recently from a2d4505 to 011b3e3 Compare December 31, 2025 15:19

Lewis-E requested review from duncanpharvey and jcstorms1 January 20, 2026 18:36

chatgpt-codex-connector bot reviewed Jan 20, 2026

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duncanpharvey reviewed Jan 20, 2026

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jcstorms1 reviewed Jan 22, 2026

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Lewis-E added 17 commits February 2, 2026 11:02

Add named pipe to dogstasd BufferReader.

6d82e6b

dogstatsd: windows named pipe support now with connect + result type …

9e50f80

…improvements

More consistent retry logic for NamedPipes

3816cf8

Improve naming & allow panic for consistent new() failures

2ccf5e5

Simplify named pipe read loop

8fcd781

Reorganize code for readability and add comments

984419c

Add test coverage for named pipe code

d0f993a

Cancel token behavior for named pipe loops

f352970

Looking at named pipe deletion and recreation

9715231

Consistent debugging and cleanup for named pipe dogstatsd code

058b46b

Add tests for named pipe error handling

c7fdfaf

Handle pipe names consistently with dogstatsd client

10d6660

Add pipe sharing check

84bf891

Try different named pipe server / read separation

efa171b

Add buffer for metrics

e26e8ae

Add test for metrics buffer

79e0839

Include named pipe in /info

195d536

Lewis-E force-pushed the lewis/SVLS-6029/dogstatsd-named-pipes branch from 669bcfa to 195d536 Compare February 2, 2026 16:31

Lewis-E commented Feb 2, 2026

View reviewed changes

Lewis-E force-pushed the lewis/SVLS-6029/dogstatsd-named-pipes branch 3 times, most recently from 07fd58c to a2d1b8f Compare February 2, 2026 17:40

Keep dogstatsd+tracer separate

704609a

Lewis-E force-pushed the lewis/SVLS-6029/dogstatsd-named-pipes branch from a2d1b8f to 704609a Compare February 2, 2026 17:40

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What does this PR do?

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Lewis-E commented Dec 26, 2025 •

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