Support for mounting a shared volume instead of copying application
files was meant to provide an option for development use cases. This
functionality has never been thoroughly tested or utilized for any use
case. It should be removed for now.

Relates tangentially to task T204591 that simplifies node support.

Change-Id: Ib70cb7bceb504841897a38d732880ba376fe67c8

All import paths and other references to the previously Blubber repo in
Phabricator have been changed to point to the new Gerrit project URL.

Note that building or testing against this change will require you to
move your working directory to `$GOPATH/src/gerrit.wikimedia.org/r/blubber`.

Contribution documentation was updated to reflect the changes, and the
`.arcvendor` submodule has been removed.

Bug: T200452
Change-Id: I3ab23e420b2825e86e2bd7c9b3da9d4de23edaa1

Summary:
Ran into a Docker error when attempting to build a node project with
more than one requirements files:

    When using COPY with more than one source file, the destination must
    be a directory and end with a /

Reviewers: dduvall, #release-engineering-team

Reviewed By: dduvall, #release-engineering-team

Tags: #release-engineering-team

Differential Revision: https://phabricator.wikimedia.org/D1080

Summary:
The implementation of D984 did not include enforcing ownership for
`build.CopyFrom` instruction and so artifacts copied from one image to
another via `copies:` were problematically owned as root.

In order to fix this behavior:
 1. `config.ArtifactConfig` `build.CopyFrom` instructions are now
    injected duration `build.PhaseInstall`
 2. `config.VariantConfig` calls `build.ApplyUser` for these artifact
    instructions as well using the `runs.as` user
 3. `build.CopyAs` was refactored to wrap any `build.Instruction` which
    should only really be used with `build.Copy` or `build.CopyFrom`.

Test Plan:
Run `go test ./...`. Run `blubber` against configuration with a variant that
uses `copies` and verify that the `COPY --from` instructions also include a
`--chown` flag.

Reviewers: thcipriani, mmodell, hashar, #release-engineering-team, demon

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Differential Revision: https://phabricator.wikimedia.org/D1002

Summary:
Introduce new `build.EntryPoint` and `build.WorkingDirectory`
instructions to allow configuration to inject them instead of hard
coding their generation in the Docker compiler.

Simplified the Docker compiler to simply iterate over build phases as
returned by a new function `build.Phases()`.

Depends on D990

Test Plan: Run `go test ./...`.

Reviewers: thcipriani, demon, hashar, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Differential Revision: https://phabricator.wikimedia.org/D991

Summary:
Introduces new `lives` configuration that provides the name/UID/GID of
the user that will own application files and installed dependencies.
This new configuration is distinct from `runs` in that the former
determines application file location ownership and the latter now only
determines runtime process ownership. Default configuration has also
been introduced for both config sections.

In addition to the new configuration, a new `build.CopyAs` instruction
has been introduced that ensures correct UID/GID ownership of files
copied into the container image, and all unqualified `build.Copy`
instructions are wrapped by the new `build.CopyAs` instruction using the
UID/GID appropriate for the current build phase. A new `build.User`
instruction is also introduced and injected into the build at the start
of certain phases to enforce ownership of `build.Run` processes.

This effective process/file ownership model is:

   PhasePrivileged - "root"
   PhasePrivilegedDropped - lives.as
   PhasePreInstall - lives.as
   PhaseInstall - lives.as
   PhasePostInstall - runs.as

Fixes T187372

Test Plan: Run `go test ./...`.

Reviewers: thcipriani, hashar, demon, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Subscribers: mmodell

Tags: #release-engineering-team

Maniphest Tasks: T187372

Differential Revision: https://phabricator.wikimedia.org/D984

Summary:
Certain meta data including the Blubber version and variant used at
invocation may be useful in downstream tracking.

Implemented abstract and Docker-specific instructions for labels and
modified the Docker compiler to include these instructions at the end of
the output for the final stage.

Depends on D816
Fixes T178022

Test Plan:
Run unit tests. Run `make && bin/blubber blubber.example.yaml production` and
verify that both `blubber.version` and `blubber.variant` labels are present
and accurate.

Reviewers: thcipriani, hashar, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Maniphest Tasks: T178022

Differential Revision: https://phabricator.wikimedia.org/D818

Summary:
Debian only provides a package for the GitHub version so it's either
this or we'd have to maintain a patch to change the import paths at
packaging, a moving target for sure.

Since it's only a development dependency, we're not too worried about
versioning it and this is a much more simple solution.

Refs T175609

Test Plan: Run `go get ./... && go test ./...`.

Reviewers: thcipriani, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Maniphest Tasks: T175609

Differential Revision: https://phabricator.wikimedia.org/D782

Summary:
Now that our Phabricator instance handles `go get` requests, we can use
a path without the `.git` suffix as the canonical import path.

Test Plan: Run `go test ./...` and `go build`.

Reviewers: thcipriani, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Differential Revision: https://phabricator.wikimedia.org/D780

Summary:
Defined new abstract `build.Volume` and corresponding
`docker.DockerVolume` instructions.

Refactored compilation of main `COPY` or `VOLUME` instruction for
application files to use the new instructions and moved injection of
these instructions out of the compiler and into `VariantConfig`. The
latter can be smarter about the following cases:

 1. When `copies` is set, simply depend on artifacts for the application
    files and do not copy anything from the build host.
 2. When `sharedvolume` is `true`, inject a `build.Volume` instruction
    for the application working directory.
 3. When neither of the above are set, copy application files from the
    host.

Fixes T174623
Depends on D768

Test Plan:
Run `go test ./...`. Run `blubber blubber.example.yaml production` and ensure:

 1. The `prep` stage has a `COPY . .` instruction.
 2. The final stage has no `COPY . .` instruction, only `COPY --from=prep`
    instructions.

Reviewers: thcipriani, mobrovac, hashar, mmodell, #release-engineering-team

Reviewed By: thcipriani, mobrovac, #release-engineering-team

Tags: #release-engineering-team

Maniphest Tasks: T174623

Differential Revision: https://phabricator.wikimedia.org/D769

Summary:
Support a `copies` variant config entry that will result in a
multi-stage build, copying both shared library files and application
directory from a previously defined variant. This is essentially a
shorthand for two `artifacts` entries that are likely to be idiomatic to
multi-stage build/prod configurations.

Defined a new abstract `build.CopyFrom` instruction and corresponding
`docker.DockerCopyFrom` instruction and refactored the writing of these
Dockerfile lines to be accomplished using an `InstructionsForPhase`
method on `config.ArtifactsConfig`.

Implemented new support for `copies` configuration in
`config.VariantConfig` and an `InstructionsForPhase` method that returns
`build.CopyFrom` instructions for both the shared library and
application directories.

Fixes T174622
Depends on D759

Test Plan:
Run `go test ./...`. Run `blubber blubber.example.yaml production` and ensure
the right `COPY --from` lines are included for the final stage.

Reviewers: thcipriani, mobrovac, hashar, mmodell, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Maniphest Tasks: T174622

Differential Revision: https://phabricator.wikimedia.org/D768

Summary:
Refactored build instructions to use concrete types and
`build.Instruction` as an interface instead of relying on a simple enum
and arbitrary string arguments. The formal types result in:

 1. Clearer internal data structures
 2. Partial compilation and proper argument quoting for all instructions
    moved into the common `build` package
 3. Higher order instructions like `build.RunAll` that easily reduce to
    compiler specific output

Test Plan: Run `arc unit` or `go test ./...`

Reviewers: thcipriani, mmodell, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Differential Revision: https://phabricator.wikimedia.org/D741