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Effective debugging of Docker containers
Bug Hunt
Examining Layers
If you find yourself in the harrowing situation of needing to debug a setup that you did not build yourself and that is based on prebuilt Docker Hub containers, you face a real challenge. You often have to deal with a layer cake: Various users have changed and modified the original Docker Hub image so that it is almost impossible to trace who is responsible for what change and when it happened.
Docker itself offers a little help here: The docker history command can be used to display the changes an image has undergone during its lifetime, including any comments and corresponding notes – which might shed some light on the matter (Figure 5).
Figure 5: docker history reveals what changes have been made to a Docker image.
Infos
- "Container Security" by Martin Loschwitz, ADMIN , issue 44, 2018, pp. 64-67, http://www.admin-magazine.com/Archive/2018/44/Dialing-up-security-for-Docker-containers/
The Author
Martin Gerhard Loschwitz is a Telekom Public Cloud architect for T-Systems and primarily works on topics such as OpenStack, Ceph, and Kubernetes.
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