[SOLVED] How to modify the `core_pattern` when building docker image

How to modify the `core_pattern` when building docker image

I want to modify the core_pattern when building docker image, and my docker file is like this:

FROM centos:7
RUN echo "core-%e" > /proc/sys/kernel/core_pattern

Then I ran docker build and I get an error

/bin/sh: /proc/sys/kernel/core_pattern: Read-only file system

Anybody help?

Solution

I needed this myself, I just found out how. it is not related to docker, but to linux in general. I am using ubuntu and I am 99% certain centos will behave the same in this regard.

it is edited via sysctl command.

see example

bash$ cat /proc/sys/kernel/core_pattern 
|/usr/share/apport/apport %p %s %c %d %P %E
bash$ sudo sysctl -w kernel.core_pattern="|/usr/share/apport/apport-kde %p %s %c %d %P %E"
kernel.core_pattern = |/usr/share/apport/apport-kde %p %s %c %d %P %E
bash$ cat /proc/sys/kernel/core_pattern 
|/usr/share/apport/apport-kde %p %s %c %d %P %E
bash$

note that value starting with | is to express commands. the core dump will be sent to the command as STDIN

Since you asked your question about docker, let me also provide a compatible answer.

FROM centos:7
RUN sudo sysctl -w kernel.core_pattern="core-%e"

for more info on the core pattern you can use in your file, instead of just %e, see https://sigquit.wordpress.com/2009/03/13/the-core-pattern/

also another related question/answer that has more details

https://unix.stackexchange.com/questions/343275/why-is-editing-core-pattern-restricted