Leaking zombie processes

[Nakilon]

FROM ruby:2.7-alpine
RUN gem update bundler
RUN apk add build-base chromium

require "ferrum"

loop do
 puts "loop"
 browser = Ferrum::Browser.new headless: true, browser_options: {"no-sandbox" => nil}
 browser.go_to "http://t.me/tomsk_region70"
 sleep 10
ensure
 browser&.quit
end

$ docker run --rm -d -v $(pwd):/app -w /app -p 8002:8000 --name temp chromium sh -c "gem install ferrum && ruby app.rb"

$ docker exec temp ps aux | grep chrome
root 41 0.1 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 42 0.1 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 62 3.6 0.0 0 0 ? Z 05:45 0:01 [chrome] <defunct>
root 64 0.1 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 71 15.8 0.0 0 0 ? Z 05:45 0:06 [chrome] <defunct>
root 98 0.1 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 99 0.2 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 115 5.5 0.0 0 0 ? Z 05:45 0:01 [chrome] <defunct>
root 118 0.1 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 124 24.7 0.0 0 0 ? Z 05:45 0:06 [chrome] <defunct>
root 155 0.3 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 156 0.3 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 173 9.6 0.0 0 0 ? Z 05:45 0:01 [chrome] <defunct>
root 175 0.3 0.0 0 0 ? Z 05:45 0:00 [chrome] <defunct>
root 181 44.0 0.0 0 0 ? Z 05:45 0:06 [chrome] <defunct>

[Nakilon]

Seems to be resolved by https://docs.docker.com/compose/compose-file/compose-file-v3/#init
I'll close when I'm sure.

[davidwessman]

@Nakilon could you describe how you solved this with #init?

[jkburges]

@davidwessman I ran into this zombie process issue just now also, the AI overview from google search gave me the solution which seems to work:

AI Overview

Zombie processes in Docker Compose environments, like in any Linux system, occur when a child process terminates but its parent process fails to reap its exit status by calling wait(). In a Docker container, if the main application running as PID 1 does not handle SIGCHLD signals and reap its child processes, these terminated children can become zombies.
Addressing Zombie Processes in Docker Compose:
Using init: true in your docker-compose.yml:
Docker Compose offers a convenient way to integrate a lightweight init system like Tini into your services by adding init: true to your service definition. This ensures that Tini runs as PID 1 inside the container, automatically handling signal forwarding and zombie process reaping.

 version: '3.8'
 services:
 my_service:
 image: my_image
 init: true # This enables Tini as the init process
 command: ["my_application"]

[davidwessman]

Thanks, need to find the solution for kubernetes :/

[jkburges]

@davidwessman you might be able to do something like:

FROM alpine:latest

# Install tini
RUN apk add --no-cache tini

# Set tini as the entrypoint
ENTRYPOINT ["/sbin/tini", "--"]

# Your actual command
CMD ["your-app", "arg1", "arg2"]

according to ChatGPT.