Profiling in Docker container

To profile a .NET application or a server running in a Docker container, you should run it with the profiler agent, and then use remote profiling in the profiler UI, as described below.

Enable profiling in Linux Docker images

• Add a new stage to your Dockerfile. For example:

  FROM alpine as yourkit-stage
  RUN wget -q https://www.yourkit.com/dotnet/download/docker/YourKit-NetProfiler-2022.3-docker.zip
  RUN unzip -q YourKit-NetProfiler-2022.3-docker.zip

• Copy profiler files and enable profiling in your image. For example:

  # Copy profiler files from the previous stage
  COPY --from=yourkit-stage /YourKit-NetProfiler /YourKit-NetProfiler
  
  # Enable profiling
  ENV CORECLR_ENABLE_PROFILING="1" \
      CORECLR_PROFILER="{E5A4ADC4-C749-400D-B066-6AC8C1D3790A}" \
      CORECLR_PROFILER_PATH_64="/YourKit-NetProfiler/bin/linux-x86-64/libynpagent.so" \
      YNP_STARTUP_OPTIONS="listen=all,port=10001"

  Please choose an appropriate agent path for your docker architecture. The path in the example above corresponds to Linux x64 (glibc), please replace it if your docker architecture differs.

  Platform	Agent path
  Linux (glibc), x86-64	/YourKit-NetProfiler/bin/linux-x86-64/libynpagent.so
  Alpine Linux (musl), x86-64	/YourKit-NetProfiler/bin/linux-musl-x86-64/libynpagent.so

Enable profiling in Windows Docker images

• Add a new stage to your Dockerfile. For example:

  FROM mcr.microsoft.com/windows/nanoserver:2004 as yourkit-stage
  RUN curl -fLOSs https://www.yourkit.com/dotnet/download/docker/YourKit-NetProfiler-2022.3-docker.zip
  RUN tar xf YourKit-NetProfiler-2022.3-docker.zip -C c:

• Copy profiler files and enable profiling in your image. For example:

  # Copy profiler files from the previous stage
  COPY --from=yourkit-stage /YourKit-NetProfiler /YourKit-NetProfiler
  
  # Enable profiling
  ENV CORECLR_ENABLE_PROFILING="1" \
      CORECLR_PROFILER="{E5A4ADC4-C749-400D-B066-6AC8C1D3790A}" \
      CORECLR_PROFILER_PATH_32="C:\YourKit-NetProfiler\bin\win32\ynpagent.dll" \
      CORECLR_PROFILER_PATH_64="C:\YourKit-NetProfiler\bin\win64\ynpagent.dll" \
      COR_ENABLE_PROFILING="1" \
      COR_PROFILER="{E5A4ADC4-C749-400D-B066-6AC8C1D3790A}" \
      COR_PROFILER_PATH_32="C:\YourKit-NetProfiler\bin\win32\ynpagent.dll" \
      COR_PROFILER_PATH_64="C:\YourKit-NetProfiler\bin\win64\ynpagent.dll" \
      YNP_STARTUP_OPTIONS="listen=all,port=10001"

Run Docker container

In this example, the agent is configured to use port=10001. Make sure that the port is available outside of Docker with the -p flag when running the container:

docker run -p 10001:10001 my_container

Connect to the profiled application

When the application is running in the container, connect to it from the profiler UI using the mapped port.

If you run Docker container and the profiler UI on the same machine, create a remote connection to localhost.

Collect profiler snapshots and logs

If you can't or don't want to connect the profiler UI to the Docker container, and instead automatically control profiling and snapshot capturing, you may want to use the startup option dir to override default snapshot directory. Map this directory in Docker, for example with -v flag, and analyze snapshots later.

Should you need the agent log file for troubleshooting purposes, map a host directory to the container and specify it with the startup option logdir.

Complete example

• Dockerfile content:

  FROM alpine as yourkit-stage
  RUN wget -q https://www.yourkit.com/dotnet/download/docker/YourKit-NetProfiler-2022.3-docker.zip
  RUN unzip -q YourKit-NetProfiler-2022.3-docker.zip
  
  FROM mcr.microsoft.com/dotnet/samples:aspnetapp
  
  # Copy profiler files from the previous stage
  COPY --from=yourkit-stage /YourKit-NetProfiler /YourKit-NetProfiler
  
  # Enable profiling
  ENV CORECLR_ENABLE_PROFILING="1" \
      CORECLR_PROFILER="{E5A4ADC4-C749-400D-B066-6AC8C1D3790A}" \
      CORECLR_PROFILER_PATH_64="/YourKit-NetProfiler/bin/linux-x86-64/libynpagent.so" \
      YNP_STARTUP_OPTIONS="listen=all,logdir=/logs,dir=/snapshots,sampling"

• Command line:

  mkdir -p $(pwd)/logs
  mkdir -p $(pwd)/snapshots
  docker build $(pwd) -t yourkit-demo
  docker run -p 10001-10010:10001-10010 -v $(pwd)/logs:/logs -v $(pwd)/snapshots:/snapshots yourkit-demo