I am trying to change inotify.max_user_instances setting for docker env on the level of Dockerfile. I am trying to do it because I am receiving this error:
Application startup exception: System.IO.IOException: The configured user limit (128) on the number of inotify instances has been reached.
I already use:
.AddJsonFile($"appsettings.json", optional: true, reloadOnChange: false);
I as well tried to use custom "WebHost.CreateDefaultBuilder(args)", because it was pointed out that it uses reloadOnChange: true with the same file.
Tried as well running in dockerfile:
RUN sysctl -w fs.inotify.max_user_watches=1048576
RUN echo fs.inotify.max_user_watches=1048576 | tee -a /etc/sysctl.conf && sysctl -p
But it was pointed out that it is impossible to run from that context.
Is there possibility to change those sysctl settings from the stage of docker image build/deployment? I am a little lost in this.
If it helps, application is using .net core 2.2
Is there possibility to change those sysctl settings from the stage of docker image build
No. The output of the image build is only a filesystem image, plus some metadata about the default environment variables and command to run when you docker run the image. It does not include running processes, sysctl values, or anything else.
Remember that sysctl settings are usually global kernel-level settings; since all Docker containers share the host's kernel, they usually share the same sysctl values. (Since containers also generally have isolated filesystems, watching for filesystem changes via inotify isn't really a common use case; if there's a substantial change in the code or other image context, it's more common to rebuild the image and then delete and recreate the container.)
There are a limited set of values you can change via docker run --sysctl but these do not include the inotify values. The only way to change this value is to run sysctl, as root, on the host, outside of Docker.