Rust MUSL support (#526)

* Rust MUSL support

Signed-off-by: Francesco Guardiani <[email protected]>

* Changed version

Signed-off-by: Francesco Guardiani <[email protected]>

* Added sccache usage to speedup builds

Signed-off-by: Francesco Guardiani <[email protected]>

* Modified path in launch.json

Signed-off-by: Francesco Guardiani <[email protected]>

* Changed APPSODY_RUN_ON_CHANGE

Signed-off-by: Francesco Guardiani <[email protected]>

* Production image uses user nobody

Signed-off-by: Francesco Guardiani <[email protected]>

Co-authored-by: Sandy Koh <[email protected]>

experimental/rust/README.md

@@ -2,7 +2,9 @@
 
 The Rust stack provides a consistent way of developing [Rust](https://rust-lang.org/) applications.
 
-This stack is based on the `Rust v1.37` runtime and allows you to develop new or existing Rust applications using Appsody.
+This stack is based on the `Rust v1.39` runtime and allows you to develop new or existing Rust applications using Appsody.
+
+The Rust stack uses [Rust MUSL support](https://doc.rust-lang.org/edition-guide/rust-2018/platform-and-target-support/musl-support-for-fully-static-binaries.html) to build fully static binaries with statically linked libc, making the built images really small.
 
 ## Templates
 

experimental/rust/image/Dockerfile-stack

@@ -1,22 +1,26 @@
-FROM rust:1.37
+FROM rust:1.39
 
-RUN apt-get update && apt-get install -y lldb
+RUN apt-get update && apt-get install -y lldb musl-tools
+RUN rustup target add x86_64-unknown-linux-musl
+RUN cargo install sccache
 
 ENV CARGO_HOME=/usr/local/cargo/deps
+ENV SCCACHE_DIR=/project/sccache
+ENV RUSTC_WRAPPER=sccache
 
-ENV APPSODY_MOUNTS=.:/project/user-app
+ENV APPSODY_MOUNTS=.:/project/user-app;~/.cache/sccache:/project/sccache
 ENV APPSODY_DEPS=$CARGO_HOME
 
 ENV APPSODY_WATCH_DIR="/project/user-app"
 ENV APPSODY_WATCH_REGEX="^(Cargo.toml|.*.rs)$"
 
-ENV APPSODY_RUN="cargo run"
-ENV APPSODY_RUN_ON_CHANGE="cargo run"
+ENV APPSODY_RUN="cargo run --target x86_64-unknown-linux-musl"
+ENV APPSODY_RUN_ON_CHANGE="$APPSODY_RUN"
 ENV APPSODY_RUN_KILL=true
 
 ENV APPSODY_TEST="cargo test"
 
-ENV APPSODY_DEBUG="cargo build && lldb-server platform --listen '*:1234' --min-gdbserver-port 5000 --max-gdbserver-port 5001 --server"
+ENV APPSODY_DEBUG="cargo build --target x86_64-unknown-linux-musl && lldb-server platform --listen '*:1234' --min-gdbserver-port 5000 --max-gdbserver-port 5001 --server"
 ENV APPSODY_DEBUG_ON_CHANGE="$APPSODY_DEBUG"
 ENV APPSODY_DEBUG_KILL=true
 

experimental/rust/image/project/Dockerfile

@@ -1,4 +1,8 @@
-FROM rust:1.37 as builder
+FROM rust:1.39 as builder
+
+# Install musl
+RUN apt-get update && apt-get install -y musl-tools
+RUN rustup target add x86_64-unknown-linux-musl
 
 WORKDIR "/project/user-app"
 
@@ -12,25 +16,27 @@ RUN cargo fetch
 COPY /user-app/src ./src
 
 # build for release
-RUN cargo build --release \
- && echo "#!/bin/bash" > run.sh \
- && bin=$(find ./target/release -maxdepth 1 -perm -111 -type f| head -n 1) \
- && echo ./${bin##*/} >> run.sh \
- && chmod 755 run.sh
+RUN cargo build --release --target x86_64-unknown-linux-musl \
+ && cp $(find ./target/x86_64-unknown-linux-musl/release -maxdepth 1 -perm -111 -type f| head -n 1) ./target/app \
+ && chmod 755 ./target/app
 
-FROM rust:1.37-slim-stretch
+# Create a "nobody" non-root user for the next image by crafting an /etc/passwd
+# file that the next image can copy in. This is necessary since the next image
+# is based on scratch, which doesn't have adduser, cat, echo, or even sh.
+RUN echo "nobody:x:65534:65534:Nobody:/:" > /etc_passwd
 
-RUN useradd rust
+FROM scratch
 
 WORKDIR "/project/user-app"
 
 # get files and built binary from previous image
-COPY --from=builder /project/user-app/run.sh /project/user-app/Cargo.toml /project/user-app/target/release/ ./
-
-USER rust
+COPY --from=builder /project/user-app/target/app ./
+COPY --from=builder /etc_passwd /etc/passwd
 
 ENV PORT 8000
 
+USER nobody
+
 EXPOSE 8000
 
-CMD ["./run.sh"]
+CMD ["./app"]

experimental/rust/stack.yaml

@@ -1,5 +1,5 @@
 name: Rust
-version: 0.1.6
+version: 0.2.0
 description: Runtime for Rust applications
 license: Apache-2.0
 language: rust

experimental/rust/templates/simple/.vscode/launch.json

@@ -9,7 +9,7 @@
             "initCommands": [
                 "platform select remote-linux",
                 "platform connect connect://localhost:1234",
-                "platform settings -w /project/user-app/target/debug"
+                "platform settings -w /project/user-app/target/x86_64-unknown-linux-musl/debug"
             ],
             "targetCreateCommands": [
                 "file rust-simple"