OTLP Exporter cmake documentation is missing some steps...

[LarryOsterman]

There are a couple of issues in how the OTLP exporters are documented in the opentelemetry-cpp repo.

They're scattered in a number of places, so I'm dropping them in a single issue, sorry about that.

1. OTLP exporters are not included in the default opentelemetry-cpp package, instead they are optional features. To enable an OTLP exporter, you need to modify your vcpkg manifest as follows:

   {
     "name": "opentelemetry-cpp",
     "features": ["otlp"]
   },

2. OTLP support using an opentelemetry exporter is only enabled if you update your cmakelists.txt to include the following:

target_link_libraries(myapplication
  PRIVATE
  opentelemetry-cpp::ostream_span_exporter
  opentelemetry-cpp::in_memory_span_exporter
  opentelemetry-cpp::otlp_http_exporter
  opentelemetry-cpp::sdk
  )

For exporters, the critical value is otlp_http_exporter. None of these fields appear to be documented :(.

4. Finally, once you add otlp_http_exporter to the list of link libraries, there are a number of packages which need to be added to your configuration to make things link:

find_package(opentelemetry-cpp CONFIG REQUIRED)
find_package(protobuf)
find_package(nlohmann_json)
find_package(CURL)
find_package(gRPC)

With these modifications, I was able to successfully incorporate the OTLP Http exporter into my application, but figuring out the magic incantations took several hours. It would be nice if they were included in the documentation for the HTTP exporter (and the other exporters).

[willie]

This has downstream effects, too, as I had the same problem using the downstream vcpkg package for open-telemetry and had to find and link the previously mentioned libraries.

However, unlike @LarryOsterman, I did not have to use find_package(gRPC) as I was only using the otlp-http feature in that port.

[LarryOsterman]

This has downstream effects, too, as I had the same problem using the downstream vcpkg package for open-telemetry and had to find and link the previously mentioned libraries.

However, unlike @LarryOsterman, I did not have to use find_package(gRPC) as I was only using the otlp-http feature in that port.

I discovered after filing this that the gRPC dependency was fixed in the OTLP port a couple of months ago. At the time I filed the bug, my repo was using a vcpkg baseline from November which had that issue. But the other dependencies (protobuf, nlohmann_json, and curl) are still needed.

[github-actions]

This issue was marked as stale due to lack of activity.

[dbarker]

The CMake files have been updated and since version v1.21.0 CI is now testing that the third party dependencies are found appropriately when find_package(opentelemetry-cpp CONFIG) is called.

The INSTALL markdown file has been updated to list the CMake targets imported by each CMake component.

Closing this issue as resolved by #3220