CI: Add container build

Add a simple Dockerfile that can build kops, and a short README on how
to build it. This generates a 425M image, which is about as tight as I
could get it in a short amount of work without just busting apart the
golang:1.6-alpine image to compress the Go layer itself. It's good
enough for what I'm planning to use it for: CI builds.

Along the way: Fix-up .gitignore to include more from k8s/.gitignore
(include editor ones, and terraform output dir).

.gitignore

@@ -1,6 +1,46 @@
-.build/
+# OSX leaves these everywhere on SMB shares
+._*
 
-# IntelliJ
+# OSX trash
-*.iml
+.DS_Store
+
+# Eclipse files
+.classpath
+.project
+.settings/**
+
+# Files generated by JetBrains IDEs, e.g. IntelliJ IDEA
 .idea/
+*.iml
 
+# Vscode files
+.vscode
+
+# Emacs save files
+*~
+\#*\#
+.\#*
+
+# Vim-related files
+[._]*.s[a-w][a-z]
+[._]s[a-w][a-z]
+*.un~
+Session.vim
+.netrwhist
+
+# Go test binaries
+*.test
+
+# Mercurial files
+**/.hg
+**/.hg*
+
+# Vagrant
+.vagrant
+network_closure.sh
+
+# make-related metadata
+/.make/
+
+# Terraform plans get put here
+/out/

docker/Dockerfile

@@ -0,0 +1,28 @@
+FROM golang:1.6-alpine
+
+# KOPS_GITISH: Modify to build at an explicit tag/gitish
+ARG KOPS_GITISH=HEAD
+
+# KUBECTL_SOURCE: Change to kubernetes-dev/ci for CI
+ARG KUBECTL_SOURCE=kubernetes-release/release
+
+# KUBECTL_TRACK: Currently latest from KUBECTL_SOURCE. Change to latest-1.3.txt, etc. if desired.
+ARG KUBECTL_TRACK=latest.txt
+
+ARG KUBECTL_ARCH=linux/amd64
+
+RUN apk add --no-cache --update build-base curl git mercurial  --virtual .kops-deps && \
+    go get -d k8s.io/kops && \
+    cd "${GOPATH}/src/k8s.io/kops" && git fetch origin && git reset --hard "${KOPS_GITISH}" && git clean -xdf && go get -d . && \
+    make && \
+    MODELS=$(readlink "${GOPATH}/bin/models") && rm "${GOPATH}/bin/models" && mv "${MODELS}" "${GOPATH}/bin/models" && \
+    GITISH=$(git show-ref -s --abbrev HEAD) && \
+    KUBECTL_VERSION=${KUBECTL_VERSION:-$(curl -SsL --retry 5 "https://storage.googleapis.com/${KUBECTL_SOURCE}/${KUBECTL_TRACK}")} && \
+    echo "=== Fetching kubectl ${KUBECTL_VERSION} ===" && \
+    curl -SsL --retry 5 "https://storage.googleapis.com/${KUBECTL_SOURCE}/${KUBECTL_VERSION}/${KUBECTL_ARCH}/kubectl" > /usr/local/bin/kubectl && \
+    chmod +x /usr/local/bin/kubectl && \
+    /usr/local/bin/kubectl version --client && \
+    cd / && rm -rf "${GOPATH}/src" && rm -rf "${GOPATH}/pkg" && rm -rf "/usr/local/go" && apk del .kops-deps && \
+    echo "=== Built kops at ${GITISH}, fetched kubectl ${KUBECTL_VERSION} ==="
+
+CMD "/go/bin/kops"

docker/README.md

@@ -0,0 +1,15 @@
+# Running Kops in Docker
+
+The Dockerfile here is offered primarily as a way to build continuous
+integration versions of `kops` until we figure out how we want to
+release/package it.
+
+To use it, e.g. (assumes your `$HOME` is correct and that `$KOPS_STATE_STORE` is correct):
+```shell
+$ docker build -t kops .
+$ KOPS="docker run -v $HOME/.aws:/root/.aws:ro -v $HOME/.ssh:/root/.ssh:ro -v $HOME/.kube:/root/.kube -it kops kops --state=$KOPS_STATE_STORE"
+```
+
+This creates a shell variable that runs the `kops` container with `~/.aws` mounted in (for AWS credentials), `~/.ssh` mounted in (for SSH keys, for AWS specifically), and `~/.kube` mounted in (so `kubectl` can add newly created clusters).
+
+After this, you can just use `$KOPS` where you would generally use `kops`, e.g. `$KOPS get cluster`.