Dockerfile

# Copied from https://github.com/docker-library/golang/blob/ff7c350f62/1.11/alpine3.9/Dockerfile
# and modified to apply a patch to the tls library and build padcheck.go
# LICENSE notice from https://github.com/docker-library/golang/blob/ff7c350f62/LICENSE follows:

# Copyright (c) 2014 Docker, Inc. All rights reserved.

# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:

#    * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#    * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#    * Neither the name of Docker, Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.

# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

FROM alpine:3.9

RUN apk add --no-cache \
		ca-certificates

# set up nsswitch.conf for Go's "netgo" implementation
# - https://github.com/golang/go/blob/go1.9.1/src/net/conf.go#L194-L275
# - docker run --rm debian:stretch grep '^hosts:' /etc/nsswitch.conf
RUN [ ! -e /etc/nsswitch.conf ] && echo 'hosts: files dns' > /etc/nsswitch.conf

COPY ./paddingmodes-go1.11.diff /tmp/paddingmodes-go1.11.diff

ENV GOLANG_VERSION 1.11.5

RUN set -eux; \
	apk add --no-cache --virtual .build-deps \
		bash \
		gcc \
		musl-dev \
		openssl \
		go \
	; \
	export \
# set GOROOT_BOOTSTRAP such that we can actually build Go
		GOROOT_BOOTSTRAP="$(go env GOROOT)" \
# ... and set "cross-building" related vars to the installed system's values so that we create a build targeting the proper arch
# (for example, if our build host is GOARCH=amd64, but our build env/image is GOARCH=386, our build needs GOARCH=386)
		GOOS="$(go env GOOS)" \
		GOARCH="$(go env GOARCH)" \
		GOHOSTOS="$(go env GOHOSTOS)" \
		GOHOSTARCH="$(go env GOHOSTARCH)" \
	; \
# also explicitly set GO386 and GOARM if appropriate
# https://github.com/docker-library/golang/issues/184
	apkArch="$(apk --print-arch)"; \
	case "$apkArch" in \
		armhf) export GOARM='6' ;; \
		x86) export GO386='387' ;; \
	esac; \
	\
	wget -O go.tgz "https://golang.org/dl/go$GOLANG_VERSION.src.tar.gz"; \
	echo 'bc1ef02bb1668835db1390a2e478dcbccb5dd16911691af9d75184bbe5aa943e *go.tgz' | sha256sum -c -; \
	tar -C /usr/local -xzf go.tgz; \
	rm go.tgz; \
	\
	cd /usr/local/go/src; \
	patch -p2 < /tmp/paddingmodes-go1.11.diff; \
	rm /tmp/paddingmodes-go1.11.diff; \
	./make.bash; \
	\
	rm -rf \
# https://github.com/golang/go/blob/0b30cf534a03618162d3015c8705dd2231e34703/src/cmd/dist/buildtool.go#L121-L125
		/usr/local/go/pkg/bootstrap \
# https://golang.org/cl/82095
# https://github.com/golang/build/blob/e3fe1605c30f6a3fd136b561569933312ede8782/cmd/release/releaselet.go#L56
		/usr/local/go/pkg/obj \
	; \
	apk del .build-deps; \
	\
	export PATH="/usr/local/go/bin:$PATH"; \
	go version

ENV GOPATH /go
ENV GOBIN $GOPATH/bin
ENV PATH $GOPATH/bin:/usr/local/go/bin:$PATH

RUN mkdir -p "$GOPATH/src" "$GOPATH/bin" && chmod -R 777 "$GOPATH"
WORKDIR $GOPATH

COPY padcheck.go /go/src
RUN cd /go/src && go install padcheck.go

ENTRYPOINT ["/go/bin/padcheck"]
CMD ["-h"]