Use multi-stage builds for docker image (#434)

Previously we used a bunch of dockerfiles to coordinate building
the cernan docker image. The future rolled up on us meanwhile and
we can now make use of multi-stage builds in Docker.

Signed-off-by: Brian L. Troutwine <blt@postmates.com>

Dockerfile

@@ -0,0 +1,51 @@
+FROM ekidd/rust-musl-builder:1.24.0 as builder
+
+RUN VERS=1.2.11 && \
+    cd /home/rust/libs && \
+    curl -LO http://zlib.net/zlib-$VERS.tar.gz && \
+    tar xzf zlib-$VERS.tar.gz && cd zlib-$VERS && \
+    CC=musl-gcc CFLAGS=-fPIC ./configure --static --prefix=/usr/local/musl && \
+    make && sudo make install && \
+    cd .. && rm -rf zlib-$VERS.tar.gz zlib-$VERS
+
+RUN cd /home/rust/libs && \
+    curl -LO https://github.com/lz4/lz4/archive/master.tar.gz && \
+    tar xfz master.tar.gz && \
+    ls && \
+    cd lz4-master && \
+    CC=musl-gcc CFLAGS=-fPIC make prefix=/usr/local/musl && \
+    sudo make install prefix=/usr/local/musl && \
+    cd .. && \
+    rm -rf master.tar.gz lz4-master
+
+RUN sudo apt-get update && \
+    sudo apt-get install -y python2.7-minimal && \
+    sudo ln -sf /usr/bin/python2.7 /usr/bin/python
+
+ENV CC=musl-gcc \
+    CFLAGS=-I/usr/local/musl/include \
+    LDFLAGS=-L/usr/local/musl/lib
+
+COPY --chown=rust:rust . /source
+RUN cd /source && cargo build --release
+
+FROM alpine:3.7
+
+RUN apk update \
+  && apk upgrade --no-cache
+
+RUN apk add --no-cache --update \
+  ca-certificates \
+  llvm-libunwind \
+  openssl && \
+  update-ca-certificates && \
+  rm -rf /var/cache/apk/* && \
+  mkdir -p /etc/cernan/scripts
+
+COPY --from=builder /source/target/x86_64-unknown-linux-musl/release/cernan /usr/bin/cernan
+COPY examples/configs/quickstart.toml /etc/cernan/cernan.toml
+
+ENV STATSD_PORT 8125
+
+ENTRYPOINT /usr/bin/cernan
+CMD ["--config", "/etc/cernan/cernan.toml"]

build-container.sh

@@ -18,9 +18,5 @@ cargo clean
 
 VERSION="${1}"
 
-mkdir -p target/bindir
-docker build -t cernan-build -f docker/build/Dockerfile .
-docker run -v $(pwd):/source -w /source -it cernan-build cargo build --release
-docker build -t quay.io/postmates/cernan:latest -t "quay.io/postmates/cernan:$VERSION" -f docker/release/Dockerfile .
+docker build -t "quay.io/postmates/cernan:$VERSION" .
 docker push "quay.io/postmates/cernan:$VERSION"
-docker push "quay.io/postmates/cernan:latest"