Restarting Play application Docker container resul

问题:

Edit: There is a related issue being discussed on Github but in another mode of deployment (Typesafe Activator UI and not Docker).

I was trying to simulate a system reboot in order to verify the Docker restart policy which declares to be able to re-run containers in the correct order.

I have a Play framework application written in Java.

The Dockerfile looks like this:

FROM ubuntu:14.04
#
#  [Java8, ...]
#
RUN chmod +x /opt/bin/playapp
CMD ["/bin/bash"]

I start it using $ docker run --restart=always -d --name playappcontainer "./opt/bin/playapp".

When I $ service docker stop && service docker restart and then $ docker attach playappcontainer the console tells me:

Play server process ID is 7
This application is already running (Or delete /opt/RUNNING_PID file)

Edit: Same result when I follow the recommendation of the Play documentation to change the location of the file to /var/run/play.pid with -Dpidfile.path=/var/run/play.pid.

Play server process ID is 7
This application is already running (Or delete /var/run/play.pid file).

---

So: Why is the file containing the RUNNING_PID not deleted when the docker daemon stops, gets restartet and restarts previously run containers?

---

When I $ docker inspect playappcontainer, it tells me:

"State": {
    "ExitCode": 255,
    "FinishedAt": "2015-02-05T17:52:39.150013995Z",
    "Paused": false,
    "Pid": 0,
    "Restarting": true,
    "Running": true,
    "StartedAt": "2015-02-05T17:52:38.479446993Z"
},

Although:

The main process inside the container will receive SIGTERM, and after a grace period, SIGKILL.

from the Docker reference on $ docker stop

To kill a running Play server, it is enough to send a SIGTERM to the process to properly shutdown the application.

from the Play Framework documentation on stopping a Play application

回答1:

I've just dockerized a Play! application and was also running into this issue - restarting the host caused the Play! application to fail to start in its container because RUNNING_PID had not been deleted.

It occurred to me that as the Play! application is the only process within its container, always has the same PID, and is taken care of by Docker, the RUNNING_PID file is (to the best of my knowledge) not actually needed.

As such I overrode pidfile.path to /dev/null by placing

javaOptions in Universal ++= Seq(
  "-Dpidfile.path=/dev/null"
)

in my project's build.sbt. And it works - I can reboot the host (and container) and my Play! application starts up fine.

The appeal for me of this approach is it does not require changing the way the image itself is produced by sbt-native-packager, just the way the application runs within it.

This works with sbt-native-packager 1.0.0-RC2 and higher (because that release includes https://github.com/sbt/sbt-native-packager/pull/510).

回答2:

I sorted out a working workaround based on the answers and my further work on this question. If I start the containers as follows, they'll be up after an (un)expected stop/restart. The conflicting RUNNING_PID file won't prevent the container from restarting.

$ sudo docker run --restart=on-failure:5 -d \
--name container my_/container:latest \
sh -c "rm -f /var/run/play.pid && ./opt/bin/start \
-Dpidfile.path=/var/run/play.pid"

What it does is deleting the file containing the process ID which is put at a specific place using an option everytime before running the binary.

回答3:

I had the exact same problem and worked my way around it by manually deleting the file every time the container would run. In order to do that I added in a companion file "start.bash" I use to start the play process from the results of the SBT dist task, the following line:

find . -type f -name RUNNING_PID -exec rm -f {} \;

Hope it helps.

回答4:

I dont know much about docker.But play do not remove RUNNING_PID on stoping the server as far as I have tested .When I deployed my app on prod mode and try to stop it by Ctrl+D and Ctrl+C it din't remove the RUNNING_PID file from project directory so I had to manually delete it .From Play docs

Normally this(RUNNING_PID) file is placed in the root directory of your play project, however it is advised that you put it somewhere where it will be automatically cleared on restart, such as /var/run:

So apart from delecting manually an workaround would be

Changing the path of RUNNING_PID and deleting it everytime server starts through some script

$ /path/to/bin/<project-name> -Dpidfile.path=/var/run/play.pid

Make sure that the directory exists and that the user that runs the Play application has write permission for it.

Using this file, you can stop your application using the kill command, for example:

$ kill $(cat /var/run/play.pid)

and you can also try docker command $ sudo docker rm --force redis

Maybe That could help

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