COS Kdump Debugger container used in COS kdump

Overview

This is a docker image used by COS kdump. It includes scripts and necessary dependencies for inspecting a kernel crash dump from a COS instance based on COS images.

Building COS Kdump Debugger Docker image

Locally (for testing the image)

For testing, you can simply build and test this docker container locally on your workstation:

  $ docker build -t cos-kdump-debugger:dev .

Using cos-kdump-debugger Image

This container requires two mount points from the host:

1. It needs the gcloud credential from your host machine. (Not required if using a GCE VM, because GCE VMs get their credential from metadata server.)
2. It needs a sosreport tarball containing the kdump.

Let's say you have the sosreport tarball located at ~/debug/sosreport-kdump-next-20190130220549.tar.xz, then you should run:

  $ docker run --rm -it \
  $ -v ~/.config/gcloud:/root/.config/gcloud \
  $ -v ~/debug/:/sos \
  $ cos-kdump-debugger:dev \
  $ --sos sosreport-kdump-next-20190130220549.tar.xz

If you only want to use the container to run some simply crash commands (useful for testing), you can run:

  $ docker run --rm -it \
  $ -v ~/.config/gcloud:/root/.config/gcloud \
  $ -v ~/debug/:/sos \
  $ cos-kdump-debugger:dev \
  $ --crash_command "bt" \
  $ --sos sosreport-kdump-next-20190130220549.tar.xz

The kdump_debugger.sh script requires the matching vmlinux for the COS kernel being used. By default, the script will fetch the vmlinux for you by looking in the GCS bucket gs://cos-tools. You can also explicitly set the path to the matching vmlinux in GCS by setting the --vmlinux_path flag.

For example:

  $ docker run --rm -it \
  $ -v ~/.config/gcloud:/root/.config/gcloud \
  $ -v ~/debug/:/sos \
  $ cos-kdump-debugger:dev \
  $ --crash_command "bt" \
  $ --sos sosreport-kdump-next-20190130220549.tar.xz
  $ --vmlinux_path gs://<path-to-vmlinux-in-storage-bucket>