Re: [atomic] "LABEL install/uninstall" guidelines

[Micah Abbott <miabbott redhat com>]

On 02/06/2017 06:47 PM, Ken Dreyer wrote:
> Are there any guidelines or policies for what to put in the "install"
> or "uninstall" labels in my Dockerfiles? Can images basically do
> whatever they want in those scripts?

I don't believe there are any guidelines for what can or cannot be used 
in those labels.

> I see examples where the install script sets up systemd unit files -
> is that the pattern these install shell scripts should always follow?

If the application requires a systemd unit file, that's what should be 
installed.  However, this is not required.

For example, the Cockpit container has an INSTALL label that runs a 
script to land a few files on the host and runs

https://github.com/cockpit-project/cockpit-container/blob/master/Dockerfile#L16

https://github.com/cockpit-project/cockpit-container/blob/master/atomic-install

> I also saw an example where an image provides "LABEL install" but no
> "LABEL uninstall". Is that bad?

Again, there aren't any strict rules about what labels to provide.  I 
think a reasonable expectation is that if you are installing something, 
you should also have a way to uninstall it.


Related to this topic of labels, there is an upstream effort to come up 
with a set of default names for labels:

https://github.com/projectatomic/ContainerApplicationGenericLabels