使用 kubectl log 命令从 Kubernetes 集群中容器内的特定文件获取日志

Question

I have an application which stores logs in a file at a configurable location. Let's say /abc/pqr/application.log

Application is being migrated to Kubernetes where it will run in a single pod. If I run kubectl log <pod-name> , I get anything that gets printed on stdout which I can redirect to a file. I want to do the other way around, I have a file containing logs at above location and I want kubectl logs <pod-name> to print logs from that file.

For example, if run kubectl logs kafka for a kafka pod deployed using bitnami/kafka , I get logs from /opt/bitnami/kafka/logs/server.log . I want to mimic this behavior.

Answer 1

kubectl logs command takes everything from stdout and stderr , so you need to supply logs there.

It's a common practice when containerised applications write their logs to stdout and stderr .

This way there are two main options:

1. Adjust the application so it writes logs to stdout and file as well. Eg using shell it can be done with tee command.

   Please find a good answers with description of the command.

2. Use a sidecar container which will be getting logs from file and translating them into its own stdout . Please find Using a sidecar container with the logging agent

Useful link about kubernetes logging (including containers):

• The Complete Guide to Kubernetes Logging