run multiple commands in docker container start - docker

Question

I have a simple docker image running on ubuntu 16.04 based on a dockerfile which CMD is "/sbin/ejabberdctl foreground". to keep the docker container alive once it started I used to run ejabberd server in foreground. However after starting the container and /sbin/ejabberdctl I need to execute another command once ejabberdctl is already running (e.g. ejabberdctl list_cluster).
Tried to add both commands to bash script, but it doesn't work. tried to run /sbin/ejbberdctl start &, it didn't work either.
Which way to dig?

Answer 1

Option A:
Create a simple bash script that runs container and list_cluster with out modifying entry point of ejabberd docker image.
#!/bin/bash
if [ "${1}" = "remove_old" ]; then
echo "removing old ejabberd container"
docker rm -f ejabberd
fi
docker run --rm --name ejabberd -d -p 5222:5222 ejabberd/ecs
sleep 5
echo -e "*******list_cluster******"
docker exec -it ejabberd ash -c "/home/ejabberd/bin/ejabberdctl list_cluster"
Option B
In option B you need to modify ejabberd official image entry point as it does not allow you to run multiple scripts on bootup. So add your script on boot up while a bit modification.
https://github.com/processone/docker-ejabberd/blob/master/ecs/Dockerfile
I will suggest using an official alpine image of 30 MB only of ejabberd instead of Ubuntu.
https://hub.docker.com/r/ejabberd/ecs/
The demo is here can be modified for Ubuntu too but this is tested against the alpine ejabberd official image.
Use ejabberd official image as a base image and ENV MASTER_NODE=ejabberd#ec2-10.0.0.1 is for the master node if you are interested in a cluster.
From ejabberd/ecs:latest
USER root
RUN whoami
COPY supervisord.conf /etc/supervisord.conf
RUN apk add supervisor
RUN mkdir -p /etc/supervisord.d
COPY pm2.conf /etc/supervisord.d/ejabberd.conf
COPY start.sh /opt/ejabberd/start.sh
RUN chmod +x /opt/ejabberd/start.sh
ENV MASTER_NODE=ejabberd#ec2-10.0.0.1
ENTRYPOINT ["supervisord", "--nodaemon", "--configuration", "/etc/supervisord.conf"]
Now create supervisors config file
[unix_http_server]
file = /tmp/supervisor.sock
chmod = 0777
chown= nobody:nogroup
[supervisord]
logfile = /tmp/supervisord.log
logfile_maxbytes = 50MB
logfile_backups=10
loglevel = info
pidfile = /tmp/supervisord.pid
nodaemon = true
umask = 022
identifier = supervisor
[supervisorctl]
serverurl = unix:///tmp/supervisor.sock
[rpcinterface:supervisor]
supervisor.rpcinterface_factory = supervisor.rpcinterface:make_main_rpcinterface
[include]
files = /etc/supervisord.d/*.conf
Now create ejabberd.conf to start ejabberd using supervisorsd. Note here join cluster argument is used to join cluster if you want to join the cluster. remove it if not needed.
[supervisord]
nodaemon=true
[program:list_cluster]
command: /opt/ejabberd/start.sh join_cluster
stdout_logfile=/dev/stdout
stdout_logfile_maxbytes=0
[program:ejabberd]
command=/home/ejabberd/bin/ejabberdctl foreground
autostart=true
priority=1
autorestart=true
username=ejabberd
exitcodes=0 , 4
A /opt/ejabberd/start.sh bash script that will list_cluster once ejabberd is up and also capable to join_cluster if an argument is passed while calling the script.
#!/bin/sh
until nc -vzw 2 localhost 5222; do sleep 2 ;echo -e "Ejabberd is booting....."; done
if [ $? -eq 0 ]; then
########## Once ejabberd is up then list the cluster ##########
echo -e "***************List_Cluster start***********"
/home/ejabberd/bin/ejabberdctl list_cluster
echo -e "***************List_Cluster End***********"
########## If you want to join cluster once up as pass the master node as ENV then pass first param like join_cluster ##########
if [ "${1}" == "join_cluster" ]; then
echo -e "***************Joining_Cluster start***********"
/home/ejabberd/bin/ejabberdctl join_cluster ejabberd#$MASTER_NODE
echo -e "***************Joining_Cluster End***********"
fi
else
echo -e "**********Ejabberd is down************";
fi
Run docker container
docker build -t ejabberd .
docker run --name ejabberd --rm -it ejabberd

Answer 2

What you're searching for it's called supervisord. In the official docker documentation you can find some examples of how to use it.
Be aware that running multiple services in the same container it's discouraged unless strictly necessary, though.