Improve duplicate name error message on container create

[marcov]

Make the error message more informative by specifying the duplicate name
and the existing container ID. Implements #189.

Opening this PR as asked by @rhatdan and agreed with @vrothberg

[rhatdan]

LGTM

[rhatdan]

@marcov I think you need to update the ffjson files. If you run make does it recompile them?

[vrothberg]

LGTM (given the CI passes)

Note that this PR does not yet fully implement #189 as there are other error cases that could be improved in a similar fashion (see https://github.com/containers/storage/blob/master/errors.go). Such cases can be duplicate ID, or layer in use, etc. I suggest looking at the code using the errors and see what can be done (in follow-up PRs).

[nalind]

@marcov could you go install github.com/pquerna/ffjson, run ffjson containers.go, and add the updated containers_ffjson.go to the patch? That should keep CI from trying to do the same at build-time.

[marcov]

@rhatdan, @nalind: I tried to run ffjson locally and it just regenerate exactly the same containers_ffjson.go.

The CI logs make this look more like an issue in the CI env:

rm -f containers_ffjson.go
ffjson containers.go
make: ffjson: Command not found
Makefile:33: recipe for target 'containers_ffjson.go' failed
make: *** [containers_ffjson.go] Error 127

[rhatdan]

I think the makefile wants to generate an updated version. If you run make locally does it execute the ffjson command?

[rhatdan]

OK I ran it locally and it attempted the compile and changed nothing. But we still need a new file. Just modify a comment in the generated file and then commit and push, and the problem should be fixed.

[marcov]

OK did like you said.

[rhatdan]

Thanks Lets see if it passes tests.

[rhatdan]

Woo Hoo, the hack worked.
@nalind PTAL

[nalind]

LGTM, merging.