fix/docker-build-permissions (#207)

Reviewed-on: graham/towerops-web#207

k8s/Dockerfile

@@ -1,5 +1,3 @@
-# syntax=docker/dockerfile:1.4
-
 # Find eligible builder and runner images on Docker Hub. We use Ubuntu/Debian
 # instead of Alpine to avoid DNS resolution issues in production.
 #
@@ -38,30 +36,22 @@ WORKDIR /app
 ENV MIX_ENV="prod"
 
 # install hex + rebar
-RUN --mount=type=cache,target=/root/.hex \
-    --mount=type=cache,target=/root/.mix \
-    mix local.hex --force \
+RUN mix local.hex --force \
     && mix local.rebar --force
 
 # install mix dependencies
 COPY mix.exs mix.lock ./
 COPY vendor vendor
-RUN --mount=type=cache,target=/root/.hex \
-    --mount=type=cache,target=/root/.mix \
-    mix deps.get --only $MIX_ENV
+RUN mix deps.get --only $MIX_ENV
 RUN mkdir config
 
 # copy compile-time config files before we compile dependencies
 # to ensure any relevant config change will trigger the dependencies
 # to be re-compiled.
 COPY config/config.exs config/${MIX_ENV}.exs config/
-RUN --mount=type=cache,target=/root/.hex \
-    --mount=type=cache,target=/root/.mix \
-    mix deps.compile
+RUN mix deps.compile
 
-RUN --mount=type=cache,target=/root/.mix \
-    --mount=type=cache,target=/root/.npm \
-    mix assets.setup
+RUN mix assets.setup
 
 COPY priv priv
 
@@ -73,21 +63,18 @@ RUN cd c_src && make
 COPY lib lib
 
 # Compile the release
-RUN --mount=type=cache,target=/root/.mix \
-    mix compile
+RUN mix compile
 
 COPY assets assets
 
 # compile assets
-RUN --mount=type=cache,target=/root/.mix \
-    mix assets.deploy
+RUN mix assets.deploy
 
 # Changes to config/runtime.exs don't require recompiling the code
 COPY config/runtime.exs config/
 
 COPY rel rel
-RUN --mount=type=cache,target=/root/.mix \
-    mix release
+RUN mix release
 
 # start a new build stage so that the final image will only contain
 # the compiled release and other runtime necessities