That's cool, but won't this conflict with the current behavior of docker build -,
which reads a raw Dockerfile from stdin, then places it in an empty context and
builds that?

How would you see these 2 behaviors co-existing?

Also check out integration-cli/docker_utils.go there are bunch of utility functions
which can make your test much shorter and more readable :)

@shykes they are already coexisting, it bufio.Peek stdin to detect if it's compressed or not using a slightly refactored archive module.

See proppy@7457af7

If it's Uncompressed that's a Dockerfile.

About docker_utils.go: I can only use it for the last Command.Run.

I need access to the Command struct otherwise to specify the working directory, and pipe stdout.

added docs, PTAL

Fixed Docs, PTAL

Fixed docs, PTAL.

nice.

Docs LGTM

@proppy Didn't you see any performance issue with bufio? I originally didn't use it because it slowed down a lot commit.

@creack PTAL removed the bufio stuff from archive

@proppy Could you rebase interactively and not add it in the first place, please?

@unclejack Done, PTAL

@unclejack PTAL cleaned up the history.

@proppy Could you also add tests for piping in uncompressed tarballs and piping in a Dockerfile, please?

@unclejack Done, PTAL

@proppy Can you rebase this PR one more time, please?

@unclejack squashed and rebased

+ go test -run ^TestContext github.com/dotcloud/docker/integration-cli
[PASSED]: build - build an image with a context tar, compression: 2
[PASSED]: build - build an image with a context tar, compression: 0

LGTM

ping @vieux

rebased

LGTM