fix Dockerfile by symlinking the wakunode binary

This is necessary becasue `COPY` creates a directory for some reason.

Resolves: #166

Signed-off-by: Jakub Sokołowski <jakub@status.im>

Dockerfile

@@ -1,5 +1,6 @@
 # BUILD IMAGE --------------------------------------------------------
-FROM alpine:3.11 AS nim-build
+
+FROM alpine:3.12 AS nim-build
 
 ARG NIM_PARAMS
 ARG MAKE_TARGET=wakunode
@@ -7,24 +8,30 @@ ARG MAKE_TARGET=wakunode
 # Get build tools and required header files
 RUN apk add --no-cache bash build-base pcre-dev linux-headers git
 
-RUN mkdir /app
 WORKDIR /app
-ADD . .
+COPY . .
 
 # Ran separately from 'make' to avoid re-doing
 RUN git submodule update --init --recursive
 
-# Build the node binary
-RUN make -j$(nproc) ${MAKE_TARGET} NIM_PARAMS="${NIM_PARAMS}"
+# Slowest build step for the sake of caching layers
+RUN make -j$(nproc) deps
+
+# Build the final node binary
+RUN make -j$(nproc) $MAKE_TARGET NIM_PARAMS="$NIM_PARAMS"
 
 # ACTUAL IMAGE -------------------------------------------------------
-FROM alpine:3.11
+
+FROM alpine:3.12
+
+ARG MAKE_TARGET=wakunode
 
 LABEL maintainer="jakub@status.im"
 LABEL source="https://github.com/status-im/nim-waku"
 LABEL description="Wakunode: Waku and Whisper client"
 
-EXPOSE 1234
+# DevP2P, LibP2P, and JSON RPC ports
+EXPOSE 30303 60000 8545
 
 # Referenced in the binary
 RUN apk add --no-cache libgcc pcre-dev
@@ -32,7 +39,11 @@ RUN apk add --no-cache libgcc pcre-dev
 # Fix for 'Error loading shared library libpcre.so.3: No such file or directory'
 RUN ln -s /usr/lib/libpcre.so /usr/lib/libpcre.so.3
 
-COPY --from=nim-build /app/build/${MAKE_TARGET} /usr/bin/wakunode
+# Copy to separate location to accomodate different MAKE_TARGET values
+COPY --from=nim-build /app/build/$MAKE_TARGET /usr/local/bin/
+
+# Symlink the correct wakunode binary
+RUN ln -sv /usr/local/bin/$MAKE_TARGET /usr/bin/wakunode
 
 ENTRYPOINT ["/usr/bin/wakunode"]
 # By default just show help if called without arguments