Verify inputs are valid

[baude]

Most sub-commands in atomic require the user to enter
some sort of valid input name.  This can typically be:

    * container name or container ID
    * an image ID
    * some portion of the name of the image as derived
      by the repo-tags

We know have a common function that can verify if the input
is valid.  It will return the container ID or image ID if
the image is valid.  This leverages the current
util.image_by_name function as well as three additional
functions that help derive container and image IDs.

[baude]

One comment on the code at -> baude@6f0f414#diff-555a8731c137f41d8ec2a5b76216bdecR926

I assumed that if we received multiple images back from util.image_by_name that we should list those image names in the ValueError we raise. I believe my code to do so is OK but I am not dead sure it covers all possibilities. The information is nice to have, but if deemed risky, I would say we omit the names and make the error message more generic.

[rhatdan]

Why is is_image and is_container returning anything other then true/false We are not using the values.

[rhatdan]

Should we be storing list of images and containers? In case is_container/Image is called multiple times?

[baude]

@rhatdan i do use the returns from is_image and is_container. I use the image or container ids as the inputs for scanning. This can be seen -> https://github.com/projectatomic/atomic/pull/164/files#diff-555a8731c137f41d8ec2a5b76216bdecR449

As for the storing of images and containers, flat answer is yes. Throughout the atomic code, there are instances of calls out to get a list of images or containers. I'm thinking one of the classes should just go ahead and do it upfront so everyone has it.

[rhatdan]

@baude Then change the names to get_image and get_container, and throw exception if it is not a container or image. I don't think we should return two pieces of data

Yes we should just grab the list of images/containers on first use. Add a function like

def get_containers(self):
      if self.containers:
            return self.containers
     self.containers = self.d.get_containers()
    return self.containers

[rhatdan]

Then call it everywhere we call self.d.get_containers()

[baude]

@rhatdan Ok updated as discussed.

[rhatdan]

Any update on this?

[baude]

@rhatdan I dont see those whitespace issues on my side so I am not sure what is going on there. The code from 7 days ago should have addressed your review comments. If not, we can huddle tomorrow.

[rhatdan]

Ok I will do a different patch to clean whitespace.

LGTM

[rhatdan]

White space is now clean.