Rails server is still running in a new opened docker container

Question

I want to deploy my rails project using Docker. So I use Docker-Compose. But I get one weird error message. When run docker-compose up(this contains db-container with postgresql, redis and web container with rails) I get a

web_1 | => Booting Puma web_1 | => Rails 4.2.4 application starting in production on http://0.0.0.0:3000 web_1 | => Runrails server -hfor more startup options web_1 | => Ctrl-C to shutdown server web_1 | A server is already running. Check /usr/src/app/tmp/pids/server.pid. web_1 | Exiting So I cannot understand why do I get this message, because every time I run docker-compose up, new containers start, not the previous. Even if want to delete these server.pid I am not able to do that, because this container isn't running.

my docker-compose.yml file

web:
  dockerfile: Dockerfile-rails
  build: .
  command: bundle exec rails s -p 3000 -b '0.0.0.0'
  ports:
    - "80:3000"
  links:
    - redis
    - db
  environment:
    - REDISTOGO_URL=redis://user@redis:6379/

redis:
  image: redis

db:
  dockerfile: Dockerfile-db
  build: .
  env_file: .env_db

Dockerfile-rails

FROM rails:onbuild

ENV RAILS_ENV=production

I don't think I need to post all my Dockerfiles

UPD: I fixed it by myself: i just deleted all my containers and ran the docker-compose up once again

Solution 1

You are using an onbuild image, so your working direcotry is mounted in the container image. This is very good for developing, since your app is updated in realtime when you edit your code, and your host system gets updated for example when you run a migration.

This also means that your host system tmp directory will be written with the pid file every time a server is running and will remain there if the server is not shut down correctly.

Just run this command from your host system:

sudo rm tmp/pids/server.pid 

This can be a real pain when you are for example using foreman under docker-compose, since just pressing ctrl+c will not remove the pid file.

Solution 2

I was stumped by the same problem for a bit until I figured out what was really going on. The real answer is further down... At first, you may want to try something like the following command in your docker-compose.yml file:

command: /bin/sh -c "rm -f /rails/tmp/pids/server.pid && rails server puma"

(I'm using Alpine and busybox to keep things tiny, so no bash! But the -c will work with bash too) This will delete the file if it exists so that you don't get stuck with the problem that the container keeps exiting and sitting there unable to run commands.

Unfortunately, that is NOT a good solution because you add an extra layer of /bin/sh ahead of the server and that prevents the server from getting the stop command. The result is that the docker stop commands won't give a graceful exit and the problem will always happen.

You could just run the rm command using docker-compose up to remove the file and then change the command back to the server and carry on.

However, the real answer is the create a simple docker-entry.sh file and make sure you call it using the exec form Entrypoint Documentation so that signals (like stop) get to the server process.

#!/bin/sh
set -e

if [ -f tmp/pids/server.pid ]; then
  rm tmp/pids/server.pid
fi

exec bundle exec "$@"

NOTE: we use exec on the last line to make sure that rails will be run as pid 1 (i.e. no extra shell) and thus get the signals to stop. And then in the Dockerfile (or the compose.yml) file add the entrypoint and command

# Get stuff running
ENTRYPOINT ["docker-entrypoint.sh"]
CMD ["rails", "server", "puma"]

And again, you MUST use the [] format so that it is exec'd instead of run as sh -c ""

Solution 3

This is an adapted version of Brendon Whateleys 👏 answer for

Docker Compose Solution

1. Create docker-entrypoint.sh

#!/bin/bash
set -e

if [ -f tmp/pids/server.pid ]; then
  rm tmp/pids/server.pid
fi

exec bundle exec "$@"

2. Adapt your docker-compose.yml

services:
  web:
    build: .
    entrypoint: /myapp/docker-entrypoint.sh
    command: ["rails", "server", "-b", "0.0.0.0"]
    volumes:
      - .:/myapp
    ports:
      - "3000:3000"

Notice that you will have to provide the path to where you mounted your app, iE: /myapp

2.5 If you encounter a permission error

Run this in your terminal before running docker-compose up or building your image. Thanks sajadghawami.

chmod +x docker-entrypoint.sh

3. Enjoy never having to remove server.pid manually again

🎉

Solution 4

for my work:

docker-compose run web bash

and then go folder by folder with the command cd (i am using win 7 toolbox) so in the end i use in the bash :

rm tmp/pids/server.pid

Solution 5

What I have done, Is to go on the bash shell of docker:

docker-compose run web /bin/bash

then remove the following file

rm tmp/pids/server.pid

Hope that it help!

View more solutions

Comments

[handkock]

The problem is: there's no server.pid file in my tmp/pids directory

[TopperH]

I think a workaround could be to run "docker-compose run web /bin/bash" and remove the pid file from there. Then try to investigate how it got there on the first place. Also you should run "docker inspect" on your container since it's not probably mounting your host directory correctly.

[Joao Costa]

Great answer. I had to set my entrypoint to "/myapp/docker-entrypoint.sh" to get this to work. Related discussion at github.com/docker/compose/issues/1393 .

[Ben Morris]

A variation of this worked for me, where I added to my startup script rm /myapp/tmp/pids/server.pid before running foreman start.

[Dan Kohn]

Fantastic answer, thank you. Note that I had to chmod +x docker-entrypoint.sh to resolve a permission denied error.

[Seafish]

Could you give an example of the entrypoint/command for docker-compose?

[Natus Drew]

This is the preferred solution

[Steven Aguilar]

I had to go into the container docker-compose run web /bin/bash and then remove the pid.

[TopperH]

@StevenAguilar this actually means you are not using an onbuild image as the OP was. In your case it would have actually been a better practice to just docker-compose rm web, since there is nothing persistent in that container

[Steven Aguilar]

@TopperH that didn't work, I still kept the error. When I went back to the server.pid I got Unable to find image 'web:latest' locally since I had removed it.

[TopperH]

@StevenAguilar are you running your rails server using docker-compose up ?

[Steven Aguilar]

@TopperH yes, I'm using docker-compose up to start the rails server

[mirageglobe]

actually i would do "rm -f /rails/tmp/pids/server.pid; rails s " rather than && as it will return exit 1 if the file does not exist.

[Brendon Whateley]

As I mentioned at the beginning, the solution using && is a hack. If that is what you want, you can replace the && with a ;. But a better solution is the modify the if statement in the suggested docker-entrypoint.sh. Consider however that either solution will make it impossible to start the container if it was shut down cleanly, since that will remove the PID file resulting in an error you desire.

[davegson]

As @dankohn suggested, run chmod +x docker-entrypoint.sh, but do this locally, before building the image! I wasted an hour or more trying to run this command in my Dockerfile - which failed hard 🤨

[davegson]

@Seafish, I added an adapted answer to solve this issue when using docker-compose

[Brendon Whateley]

This looks like it is for the case where the PID file is outside the container, which wasn't the case in the original question. Keeping the PID outside the container doesn't make any sense because the PID is only unique inside a container, meaning it can't reliably do anything across containers.

[Artur INTECH]

Docker guide states the same docs.docker.com/compose/rails.