Set timestamp when prebuilding lib.rs (#526)

* Set timestamp in dummy build

* Touch the new lib.rs

Author: nmattia

.dockerignore

@@ -12,6 +12,7 @@ out
 arg.in
 Dockerfile
 *.wasm
+*.swp
 
 # filter out all "hidden" files and directories
 # (.git, .dfx, .*ignore, etc)

Dockerfile

@@ -47,14 +47,16 @@ RUN cargo install ic-cdk-optimizer --version 0.3.1
 
 # Pre-build all cargo dependencies. Because cargo doesn't have a build option
 # to build only the dependecies, we pretend that our project is a simple, empty
-# `lib.rs`. Then we remove the dummy source files to make sure cargo rebuild
-# everything once the actual source code is COPYed (and e.g. doesn't trip on
-# timestamps being older)
+# `lib.rs`. When we COPY the actual files we make sure to `touch` lib.rs so
+# that cargo knows to rebuild it with the new content.
 COPY Cargo.lock .
 COPY Cargo.toml .
 COPY src/cubehash src/cubehash
 COPY src/internet_identity/Cargo.toml src/internet_identity/Cargo.toml
-RUN mkdir -p src/internet_identity/src && touch src/internet_identity/src/lib.rs && cargo build --target wasm32-unknown-unknown --release -j1 && rm -rf src
+RUN mkdir -p src/internet_identity/src \
+    && touch src/internet_identity/src/lib.rs \
+    && cargo build --target wasm32-unknown-unknown --release -j1 \
+    && rm -rf src
 
 FROM deps as build
 
@@ -65,6 +67,8 @@ ARG II_ENV=production
 
 RUN npm ci
 RUN npm run build
+
+RUN touch src/internet_identity/src/lib.rs
 RUN cargo build --target wasm32-unknown-unknown --release -j1
 RUN sha256sum dist/*
 RUN sha256sum /cargo_target/wasm32-unknown-unknown/release/internet_identity.wasm