V style logging

[ivan4th]

Virtlet logging settings:
-v=0: no info logging. V(0) can be used for some important info messages but as of now it isn't used in such way.
-v=1: minimal info logging (startup message)
-v=2: same logging as before this PR. This level is set in CMD in Dockerfile
-v=3: added back some of the logging removed in #73 on this log level. Complex objects are dumped using go-spew

Level 4 and higher isn't used at the moment.

It's now possible to set log level for docker-compose like this:

VIRTLET_LOGLEVEL=3 docker-compose up

Besides, VirtletManager.ListImages() was not returning nil response in case of error,
fixed it.

Fixes #74

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This change is 

[jellonek]

Small nits.

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Reviewed 7 of 7 files at r1.
Review status: all files reviewed at latest revision, 5 unresolved discussions.

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pkg/manager/manager.go, line 151 at r1 (raw file):

  }
  response := &kubeapi.PodSandboxStatusResponse{Status: status}
  glog.V(3).Infof("PodSandboxStatus response: #%v", status)

As this status does not have an useful Stringer it's IMO pointless to add such log. A bit better would be use of status.GetStatus().GetState() but AFAIR it also has some dummy crap there.

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pkg/manager/manager.go, line 157 at r1 (raw file):

func (v *VirtletManager) ListPodSandbox(ctx context.Context, in *kubeapi.ListPodSandboxRequest) (*kubeapi.ListPodSandboxResponse, error) {
  filter := in.GetFilter()
  glog.V(3).Infof("Listing sandboxes with filter: %#v", filter)

Same as above for status.

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pkg/manager/manager.go, line 244 at r1 (raw file):

  }
  response := &kubeapi.ListContainersResponse{Containers: containers}
  glog.V(3).Infof("ListContainers rseponse: %#v", response)

Typo. Also same as status, response in this manner is unusable/unreadable.

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pkg/manager/manager.go, line 269 at r1 (raw file):

  if err != nil {
      glog.Errorf("Error when listing images: %v", err)
      return nil, err

Good catch.

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pkg/manager/manager.go, line 272 at r1 (raw file):

  }
  response := &kubeapi.ListImagesResponse{Images: images}
  glog.V(3).Infof("ListImages response: %#v", err)

There should be simple %v.

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Comments from Reviewable

[ivan4th]

Review status: all files reviewed at latest revision, 5 unresolved discussions.

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pkg/manager/manager.go, line 157 at r1 (raw file):

Previously, jellonek (Piotr Skamruk) wrote…

Same as above for status.

Are filter details really useless? (Id, State, LabelSelector)? Maybe you meant response output below?

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pkg/manager/manager.go, line 272 at r1 (raw file):

Previously, jellonek (Piotr Skamruk) wrote…

There should be simple %v.

Are you sure that image list is readable enough when displayed via plain `%v`? That's spammy logging level, maybe it's ok to have more output there?

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Comments from Reviewable

[jellonek]

Review status: all files reviewed at latest revision, 5 unresolved discussions.

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pkg/manager/manager.go, line 157 at r1 (raw file):

Previously, ivan4th (Ivan Shvedunov) wrote…

Are filter details really useless? (Id, State, LabelSelector)?
Maybe you meant response output below?

AFAIR they look like "random pointers" in this output. Am I wrong? I have to recheck produced output... Instead of getting real values for Id, State, LabelSelector in effect you will see only "some pointers" as values.

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pkg/manager/manager.go, line 272 at r1 (raw file):

Previously, ivan4th (Ivan Shvedunov) wrote…

Are you sure that image list is readable enough when displayed via plain %v? That's spammy logging level, maybe it's ok to have more output there?

You are returning there `err`, not image list - so we are both wrong :) `ListImagesResponse` (as other similar responses) have only stub for `Stringer` interfaces which is not recursive and so, it only shows pointer to list which it have inside, so IMO it's useless info there...

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Comments from Reviewable

[jellonek]

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Reviewed 10 of 10 files at r2.
Review status: all files reviewed at latest revision, 5 unresolved discussions.

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Comments from Reviewable