JDK http client based sender is not on the classpath

[chengchen]

Describe the bug

Hello,

The original issue we were facing was described in this discussion. In short, we cannot use okhttp as metrics sender because of lack of support on Proxy-Authorization header.

What we were trying to workaround this issue is by using JDK http client based sender instead. This should have worked because we saw this implementation in place. However, it's not working correctly with the java agent version.

I inspected what's on the classpath of the built agent jar, and noticed that opentelemetry-exporter-sender-jdk is actually not packaged. This might be a bug? I tested locally, after adding this line to the javaagent-tooling/build.gradle.kts file, the agent starts to allow choosing between 2 implementations:

More concretely, this would happen with the fix:

1. If nothing is specified, the warning will be logged and okhttp will be picked by default:

2. If we run the application with this arg -Dio.opentelemetry.exporter.internal.http.HttpSenderProvider=io.opentelemetry.exporter.sender.okhttp.internal.OkHttpHttpSenderProvider, there is no more warning and it uses okhttp as sender.

3. If we run the application with this arg -Dio.opentelemetry.exporter.internal.http.HttpSenderProvider=io.opentelemetry.exporter.sender.jdk.internal.JdkHttpSenderProvider, there is no warning either and it uses JDK http client as sender.

Correct me if I am wrong, I believe this is the expected behaviour?
Thanks a lot in advance for your insights 🙏

Steps to reproduce

Run a jar with args: -javaagent:opentelemetry-javaagent.jar -Dotel.metrics.exporter=otlp -Dio.opentelemetry.exporter.internal.http.HttpSenderProvider=io.opentelemetry.exporter.sender.jdk.internal.JdkHttpSenderProvider ...

Expected behavior

We should see JDK http client doing the metrics sending.

Actual behavior

We see it's still the okhttp client doing the metrics sending.

Javaagent or library instrumentation version

any version (I built a fresh version from main branch)

Environment

(Irrelevant)

JDK:
openjdk version "21.0.2" 2024-01-16 LTS
OpenJDK Runtime Environment Temurin-21.0.2+13 (build 21.0.2+13-LTS)
OpenJDK 64-Bit Server VM Temurin-21.0.2+13 (build 21.0.2+13-LTS, mixed mode)

OS:
MacOS 15.5 (24F74)

Additional context

No response

[laurit]

I inspected what's on the classpath of the built agent jar, and noticed that opentelemetry-exporter-sender-jdk is actually not packaged. This might be a bug?

Not really a bug. The jdk sender was added later than the okhttp one. It is mostly targeted to the users who don't wish to have the okhttp dependency. The downside of the jdk http sender is that it requires java 11 and does not support grpc. Since agent needs to support java 8 and grpc we are using the okhttp sender. Ideally you should be able to add the jdk http sender as an agent extension, see https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/examples/extension There was an issue that prevented using the jdk http sender jar as an agent extension, but I believe that was already resolved a while ago. I'd suggest you first try whether you can add the jdk http sender as an extension.

[chengchen]

Hi @laurit thanks for the quick reply 👍

I am not very familiar with the extensions to be honest but I did try this and it doesn't work:

java -jar my_app.jar
    -javaagent:$buildDir/libs/opentelemetry-javaagent-original.jar
    -Dotel.javaagent.extensions=$buildDir/libs/opentelemetry-exporter-sender-jdk-1.51.0.jar
    -Dio.opentelemetry.exporter.internal.http.HttpSenderProvider=io.opentelemetry.exporter.sender.jdk.internal.JdkHttpSenderProvider
...

Or I have to build an extension myself? Thanks again!

[jack-berg]

I don't think you'll be able to do this without open-telemetry/opentelemetry-java#7446

[chengchen]

Hi @jack-berg you mean if your PR is merged the extension way should work?

java -jar my_app.jar
    -javaagent:$buildDir/libs/opentelemetry-javaagent-original.jar
    -Dotel.javaagent.extensions=$buildDir/libs/opentelemetry-exporter-sender-jdk-1.51.0.jar
    -Dio.opentelemetry.exporter.internal.http.HttpSenderProvider=io.opentelemetry.exporter.sender.jdk.internal.JdkHttpSenderProvider
...

To be honest, I don't mind at all 😄
I just want to avoid forking the repo and keep maintaining it (since you guys are doing a good job).
Thanks btw 🙏

[jack-berg]

Yes I believe so.

[jaydeluca]

@chengchen just in case you didn't see, open-telemetry/opentelemetry-java#7446 has been merged and released as part of 1.52.0

[chengchen]

Thanks @jaydeluca for the heads up 👍 I will spend some time to test it

[jack-berg]

Did it work as expected now @chengchen?

[chengchen]

Hi @jack-berg our team said it's working now. Thanks a lot for the change 🙏