implement raw pullimage functionality

[runcom]

Implements a basic and raw pull image functionality (that works though). I left a lot of TODO(s) in the code just to remind us what still needs to be fixed/changed - mainly containers/storage integration and some other stuff with containers/image.

# make sure /var/lib/ocid exists and you can write there (well, ocid can write there)

$ ./ocid &

# we need a way from k8s to tell us more about the image
# in ocid we can just assume is a docker:// image always for now
# btw, I put this on the client just to show this off

# with the above I mean "docker://" should be provided by the Kubelet API
$ ./ocic pullimage docker://busybox

$ ls -l /var/lib/ocid/images/ 
total 4
drwxr-xr-x. 2 amurdaca amurdaca 4096 Jul 20 10:42 busybox:latest

$ ls -l /var/lib/ocid/images/busybox:latest 
total 660
-rw-rw-r--. 1 amurdaca amurdaca   1459 Jul 20 10:42 2b8fd9751c4c0f5dd266fcae00707e67a2545ef34f9a29354585f93dac906749.tar
-rw-rw-r--. 1 amurdaca amurdaca 667590 Jul 20 10:42 8ddc19f16526912237dd8af81971d5e4dd0587907234be2b83e249518d5b673f.tar
-rw-r--r--. 1 amurdaca amurdaca    505 Jul 20 10:42 manifest.json

Signed-off-by: Antonio Murdaca runcom@redhat.com

[runcom]

/cc @nalind @mrunalp @mtrmac

[runcom]

This PR is based on #13 to fix the initial Godep imports

Last commit pulls in containers/image dep (I'll squash it with the second commit to not break git bisect). A notable thing about this is that it pulls in "k8s.io/kubernetes" because in containers/image we import k8s with that path while mrunalp/ocid import k8s as "github.com/kubernetes/kubernetes"

Please review individual commits

[mtrmac]

This disables TLS verification! We need that either hardcoded-on, or figure out a configuration story.

[runcom]

Yes, that's just a POC to describe the raw flow.. I'll update accordingly after we figure that out..

[mtrmac]

At least file an issue in ocid or add a loud comment to the code, then, please; we will all forget about this line comment in a day or two.

[mrunalp]

We can add TODOs and create issues on the repo to make sure that it is addressed.

[runcom]

I'll open some issues later this evening (as well as adding some other todo)

[mtrmac]

Overall I’d prefer to move the skopeo copy.go core into containers/image, have ocid just prepare the source and destination containers/image/types.ImageReference values, and then call into the copy library, instead of copy&pasting and separately maintaining the 60 or so lines (which will be much more if we decide to do any kinds of format conversion).

[mtrmac]

… all of which will require building a bit more infrastructure in containers/image, like the ImageContext and context.Context. So this PR does work as a POC / prototype implementation, I just hope that it is not the final state.

[runcom]

@mtrmac it isn't, I'm working for the imagecontext story and we'll figure out copy inside containers/image

[mrunalp]

@mtrmac We are making progress on the bits that we know. None of this is expected to be final state but will continue evolving. Working on these bits will help us identify what is missing in libraries and upstream so we fix things there and improve the integration here.

[runcom]

addressed @mtrmac's comments - added some other TODOs and explanations (now back to containers/image)

[mrunalp]

s/failed failed/failed/

[runcom]

fixed - wanted to be clear about the fact the operation failed 😄 (joking)

[mrunalp]

Heh :laugh:

[mrunalp]

Tested. LGTM.