feat(docker): build and install dex

Je me suis dit que ça pouvait être pratique d'avoir 'dex' dans l'instance.

release/docker/Dockerfile

@@ -9,6 +9,7 @@ LABEL version="0.1.0"
 LABEL description="Duniter server (Crypto-currency software to manage libre currency such as Ğ1)"
 
 ARG DUNITER_UI_VER="1.7.x"
+ARG INSTALL_DEX="no"
 
 RUN apk update && \
 	apk add ca-certificates curl && \
@@ -25,8 +26,8 @@ RUN curl https://sh.rustup.rs -sSf | sh -s -- -y
 
 # build duniter
 RUN PATH=${HOME}/.cargo/bin:${PATH} \
-	RUSTFLAGS="-C target-feature=-crt-static" \
-	make -C release ADD_DEBUG=N server-gui clean \
+	RUSTFLAGS="-C target-feature=-crt-static -L/usr/lib" \
+	make -C release ADD_DEBUG=N INSTALL_DEX=${INSTALL_DEX} server-gui clean \
 	&& rm -rf work/extra
 
 # ------------------------------------------------------------------------------
@@ -35,6 +36,8 @@ RUN PATH=${HOME}/.cargo/bin:${PATH} \
 
 FROM node:10-alpine
 
+ARG INSTALL_DEX="no"
+
 # install jq
 RUN apk add jq
 
@@ -46,8 +49,10 @@ RUN mkdir -p /var/lib/duniter /etc/duniter && chown duniter:duniter /var/lib/dun
 # copy the build artifact from the build stage
 COPY --from=build --chown=duniter:duniter /duniter/work /duniter
 
-# copy duniter wrapper
+# copy wrappers
 COPY release/docker/duniter.sh /usr/bin/duniter
+COPY release/docker/dex.sh /usr/bin/dex
+RUN [ "$INSTALL_DEX" = yes ] || rm /usr/bin/dex
 
 # copy entrypoint
 COPY release/docker/docker-entrypoint.sh /