Generating Go Bindings with Docker

This patch introduces the ability to generate Go language bindings using
Docker with `Dockerfile-go` and a spec file provided at runtime:

        # builds the container image
        $ docker build -t csi/golang -f Dockerfile-go .

        # emits the go bindings to stdout
        $ cat spec.md | docker run -i csi/golang

If the image is run without content available on STDIN then the
following error is emitted.

        $ docker run csi/golang
        usage: cat spec.md | docker run -i golang/csi

        $ docker run -i csi/golang
        usage: cat spec.md | docker run -i golang/csi

The image can also be used to emit the generated protobuf instead of the
golang bindings:

        # emits the protobuf to stdout
        $ cat spec.md | docker run -i csi/golang proto

Author: akutz

Dockerfile-go

@@ -0,0 +1,69 @@
+FROM golang:1.9.3-alpine as build
+MAINTAINER Andrew Kutz <[email protected]>
+
+# The versions of the software used in the build image. Please note
+# that the version of the protobuf Go packages and their transitive
+# dependencies are defined in the local files lib/go/Gopkg.toml and
+# lib/go/Gopkg.lock.
+ENV PROTOC_VER 3.5.1
+ENV DEP_VER 0.4.1
+
+ENV PKGPATH ${GOPATH}/src/csi
+RUN mkdir -p ${PKGPATH}
+WORKDIR ${PKGPATH}
+
+# Update the package cache and install the required tools.
+RUN apk update && apk add unzip curl git
+
+# Download protoc.
+ENV PROTOC_ZIP protoc-$PROTOC_VER-linux-x86_64.zip
+ENV PROTOC_BIN bin/protoc
+RUN curl -LO https://github.com/google/protobuf/releases/download/v${PROTOC_VER}/${PROTOC_ZIP} && \
+  unzip ${PROTOC_ZIP} && \
+  chmod 0755 ${PROTOC_BIN} && \
+  mv ${PROTOC_BIN} /usr/local/bin
+
+# Download dep.
+ENV DEP_BIN dep-linux-amd64
+RUN curl -LO https://github.com/golang/dep/releases/download/v${DEP_VER}/${DEP_BIN} && \
+  chmod 0755 ${DEP_BIN} && \
+  mv ${DEP_BIN} /usr/local/bin/dep
+
+# Copy the Go source file, dependency manifest, and lock file into the image.
+COPY lib/go/csi.go .
+COPY lib/go/Gopkg.toml .
+COPY lib/go/Gopkg.lock .
+
+# Download the Go dependencies.
+RUN dep ensure -v
+
+# Build the protogen-go binary.
+ENV PROTOC_GEN_GO_BIN protoc-gen-go
+RUN go build -o /usr/local/bin/${PROTOC_GEN_GO_BIN} ./vendor/github.com/golang/protobuf/protoc-gen-go
+
+# Start the second build stage.
+FROM alpine:3.7
+RUN mkdir -p /csi
+WORKDIR /csi
+
+# The versions of the software used in the primary image. 
+ENV GLIBC_VERSION 2.26-r0
+
+# Download and install glibc.
+# This step is credited to https://github.com/jeanblanchard/docker-alpine-glibc.
+RUN apk update && apk add curl
+RUN curl -Lo /etc/apk/keys/sgerrand.rsa.pub https://github.com/raw/sgerrand/alpine-pkg-glibc/master/sgerrand.rsa.pub && \
+  curl -Lo glibc.apk "https://github.com/sgerrand/alpine-pkg-glibc/releases/download/${GLIBC_VERSION}/glibc-${GLIBC_VERSION}.apk" && \
+  curl -Lo glibc-bin.apk "https://github.com/sgerrand/alpine-pkg-glibc/releases/download/${GLIBC_VERSION}/glibc-bin-${GLIBC_VERSION}.apk" && \
+  apk add glibc-bin.apk glibc.apk && \
+  /usr/glibc-compat/sbin/ldconfig /lib /usr/glibc-compat/lib && \
+  echo 'hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4' >> /etc/nsswitch.conf
+
+# Copy the protoc and protoc-gen-go binaries from the build image.
+COPY --from=build /usr/local/bin/protoc* /usr/local/bin/
+
+# Copy the entrypoint script from the local lib/go directory.
+COPY lib/go/spec.sh .
+RUN chmod 0755 spec.sh
+
+ENTRYPOINT [ "./spec.sh" ]

lib/go/Gopkg.lock

@@ -0,0 +1,29 @@
+# Refer to https://github.com/golang/dep/blob/master/docs/Gopkg.toml.md
+# for detailed Gopkg.toml documentation.
+#
+# Refer to https://github.com/toml-lang/toml for detailed TOML docs.
+
+# The following packages are required because they're either build
+# tools or are dependencies only if the "csi" package is already
+# generated. However, if the "csi" package is removed (a valid
+# condition), a "dep ensure" will not fetch the dependencies it
+# no longer sees in the project's dependency graph. Including the
+# dependencies in the "required" list ensures they're always
+# downloaded.
+required = [
+  "github.com/golang/protobuf/protoc-gen-go",
+  "golang.org/x/net/context",
+  "google.golang.org/grpc"
+]
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/golang/protobuf"
+
+[[constraint]]
+  branch = "master"
+  name = "golang.org/x/net"
+
+[[constraint]]
+  name = "google.golang.org/grpc"
+  version = "1.6.0"

lib/go/Gopkg.toml

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+# Check to see if there is any content in STDIN. If nothing is read
+# after 1 second, then exit with an error.
+if IFS= read -rt 1 line; then
+  echo "$line" > csi.spec
+else
+  echo "usage: cat spec.md | docker run -i golang/csi"
+  exit 1
+fi
+
+while IFS= read -r line; do
+  echo "$line" >> csi.spec
+done
+
+sed -ne '/```protobuf$/,/```$/ p' < csi.spec | \
+  sed -e 's@^```.*$@////////@g' > csi.proto
+
+if [ "$1" = "proto" ]; then
+  cat csi.proto
+else
+  protoc -I . --go_out=plugins=grpc:. csi.proto
+  cat csi.pb.go
+fi