Why does docker compose exit right after starting? - docker

Question

I'm trying to configure docker-compose to use GreenPlum db in Ubuntu 16.04. Here is my docker-compose.yml:
version: '2'
services:
greenplum:
image: "pivotaldata/gpdb-base"
ports:
- "5432:5432"
volumes:
- gp_data:/tmp/gp
volumes:
gp_data:
The issue is when I run it with sudo docker-compose up the GrrenPlum db is shutdowm immedately after starting. It looks as this:
greenplum_1 | 20170602:09:01:01:000050 gpstart:e1ae49da386c:gpadmin-[INFO]:-Starting Master instance 72ba20be3774 directory /gpdata/master/gpseg-1
greenplum_1 | 20170602:09:01:02:000050 gpstart:e1ae49da386c:gpadmin-[INFO]:-Command pg_ctl reports Master 72ba20be3774 instance active
greenplum_1 | 20170602:09:01:02:000050 gpstart:e1ae49da386c:gpadmin-[INFO]:-No standby master configured. skipping...
greenplum_1 | 20170602:09:01:02:000050 gpstart:e1ae49da386c:gpadmin-[INFO]:-Database successfully started
greenplum_1 | ALTER ROLE
dockergreenplumn_greenplum_1 exited with code 0 <<----- Here
Actually, when I start it with just sudo docker run pivotaldata/gpdb-base it's ok.
What's wrong with the docker compose?

Answer 1

First of all, be cautious running this image: the image looks to be badly maintained, and the information on Docker Hub indicates it's neither "official", nor "supported" in any way;
2017-01-09: Toolsmiths reviewed this image; it is not one we create. We make no promises about whether this is up to date or if it works. Feel free to email pa-toolsmiths#pivotal.io if you are the owner and are interested in collaborating with us on this image.
When using images from Docker Hub, it's recommended to either use official images, or when not available, prefer automated builds (in which case the source code of the image can be verified to see what's used to build theimage).
I think the image is built from this GitHub repository, which means it has not been updated for over a year, and uses an outdated (CentOS 6.7) base image that has a huge amount of critical vulnerabilities
Back to your question;
I tried starting the image, both with docker-compose and docker run, and both resulted in the same for me.
Looking at that image, it is designed to be run interactively, or to be used as a base image (and overriding the command).
I inspected the image to find out what the container's command is;
docker inspect --format='{{json .Config.Cmd}}' pivotaldata/gpdb-base
["/bin/sh","-c","echo \"127.0.0.1 $(cat ~/orig_hostname)\" >> /etc/hosts && service sshd start && su gpadmin -l -c \"/usr/local/bin/run.sh\" && /bin/bash"]
So, this is what's executed when the container is started;
echo "127.0.0.1 $(cat ~/orig_hostname)" >> /etc/hosts \
&& service sshd start \
&& su gpadmin -l -c "/usr/local/bin/run.sh" \
&& /bin/bash"
Based on the above, there is no "foreground" process in the container, so the moment /usr/local/bin/run.sh finishes, a bash shell is started. A bash shell wothout a tty attached, exits immediately, at which point the container exits.
To run this image
(Again; be cautious running this image)
Either run the image interactively, by passing it stdin and a tty (-i -t, or -it as a shorthand);
docker run -it pivotaldata/gpdb-base
Or can run it "detached", as long as a tty is passed as well (add the -d and -t flags, or -dt as a shorthand); doing so, keeps the container running in the background;
docker run -dit pivotaldata/gpdb-base
To do the same in docker-compose, add a tty to your service;
tty: true
Your compose file will then look like this;
version: '2'
services:
greenplum:
image: "pivotaldata/gpdb-base"
ports:
- "5432:5432"
tty: true
volumes:
- gp_data:/tmp/gp
volumes:
gp_data: