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I have a laravel project which I am using with docker. Currently I am using a single container to host all the services (apache, mySQL etc) as well as the needed dependencies (project files, git, composer etc) I need for my project.

From what I am reading the current best practice is to put each service into a separate container. So far this seems simple enough since these services are designed to run at length (apache server, mySQL server). When I spin up these 'service' containers using -d they remain running (docker ps) since their main process continuously runs.

However, when I remove all the services from my project container, then there is no main process left to continuously run. This means my container immediately exits once spun up.

I have read the 'hacks' of running other processes like tail -f /dev/null, sleep infinity, using interactive mode, installing supervisord (which I assume would end up watching no processes in such containers?) and even leaving the container to run in the foreground (taking up a terminal console...).

How do I network such a container to keep it running like the abstracted services but detached without these hacks? I cannot seem to find much information on this in the official docker docs nor can I find any examples of other projects (please link any)

EDIT: I am not talking about volumes / storage containers to store the data my project processes, but rather how I can use a container to store the project itself and its dependencies that aren't services (project files, git, composer)

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myol
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  • Are you saying you want a container that is storage only and has no processes? – Joachim Isaksson Apr 01 '16 at 12:01
  • Clarified the question – myol Apr 01 '16 at 12:04
  • @JoachimIsaksson Although are storage containers / volumes also used for the project itself? – myol Apr 01 '16 at 12:05
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    You can definitely use them, I usually separate even simple web sites in two containers, one with the web site/web root itself and a separate one with bog standard `nginx` just pulled from docker hub. That makes it trivial to version them independently, if nginx gets a security update I can just change version without rebuidling anything (or, even better, the customer can apply security updates in nginx themselves by just pulling a new version) – Joachim Isaksson Apr 01 '16 at 12:45
  • @JoachimIsaksson thank you. Tthis is my 'Aha' moment. I kept reading volumes as being something to store a projects data and not the project files itself. Please feel free to post an answer so I can give you proper credit. – myol Apr 01 '16 at 13:06

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when you run the container try running with the flags ...

docker run -dt ..... etc

you might even try .....

docker run -dti ..... etc

let me know if this brings any joy. has certainly worked for me on occassions.

i know you wanted to avoid hacks but if the above fails then also add ...

CMD cat

to the end of your Dockerfile - it is a hack but is the cleanest hack :)

danday74
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So after reading this a few times along with Joachim Isaksson's comment, I finally get it. Tools don't need the containers to run continuously to use. Proper separation of the project files, services (mySQL, apache) and tools (git, composer) are done differently.

The project files are persisted within a data volume container. The services are networked since they expose ports. The tools live in their own containers which share the project files data volume - they are not networked. Logs, databases and other output can be persisted in different volumes.

When you wish to run one of these tools, you spin up the tool container by passing the relevant command using docker run. The tool then manipulates the data within the directory persisted within the shared volume. The containers only persist as long as the command to manipulate the data within the shared volume takes to run and then the container stops.

I don't know why this took me so long to grasp, but this is the aha moment for me.

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myol
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