add mixer_debug docker image target

[ayj]

Add a mixer docker image using the debug_base image (similar to manager). This is in preparation for #276 which will eventually auto-build docker images with consistent tags on merge into master via Jenkins.

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This change is 

[douglas-reid]

Seems reasonable to me.

We probably should add some comment to the docker build rules about keeping the two sets of arguments and ports in sync moving forward to avoid drift between debug and other.

[codecov-io]

Codecov Report

Merging #277 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #277   +/-   ##
=======================================
  Coverage   83.83%   83.83%           
=======================================
  Files          50       50           
  Lines        2827     2827           
=======================================
  Hits         2370     2370           
  Misses        431      431           
  Partials       26       26

Impacted Files	Coverage Δ
pkg/config/manager.go	97.22% <ø> (-2.78%)	❌
pkg/adapterManager/parallelManager.go	95.23% <ø> (ø)	✅
adapter/prometheus/server.go	89.47% <ø> (+10.52%)	✅

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[ayj]

@douglas-reid, re: keeping two sets in sync, one option is to define a bazel macro to generate images for each base type, e.g.

def mixer_docker_build(name, **kwargs):
    bases = [
        { "suffix": "", "image": "@docker_ubuntu//:xenial", },
        { "suffix": "_debug", "image": "@ubuntu_xenial_debug//file", }
    ]
    for base in bases:
        docker_build(
            name = name+base["suffix"],
            base = base["image"],
            **kwargs
        )

mixer_docker_build(
    name = "mixer",
    entrypoint = [
        "/usr/local/bin/mixs",
        "server",
        "--globalConfigFile=/etc/opt/mixer/globalconfig.yml",
        "--serviceConfigFile=/etc/opt/mixer/serviceconfig.yml",
        "--logtostderr",
        "--v=2",
    ],
    ports = ["9091"],
    repository = "istio",
    tags = ["manual"],
    tars = [
        ":mixer_tar",
        "//testdata:configs_tar",
    ],
)

[douglas-reid]

I like the macro approach, if others are OK with it.

[douglas-reid]

Feel free to update with / without the macro approach. We can address that in a subsequent CL.

[ayj]

Updated to use the macro approach - PTAL. Also, I don't have write access to istio.io/mixer. Someone else will need to merge (or grant me access).