fix: build artifacts owned by root on Linux

Fixes #175

Author: flaki

builder/builder.go

@@ -157,7 +157,11 @@ func (b *Builder) dockerBuildForLang(lang string) (*BuildResult, error) {
 
 	result := &BuildResult{}
 
-	outputLog, err := b.Config.CommandRunner.Run(fmt.Sprintf("docker run --rm --mount type=bind,source=%s,target=/root/runnable %s subo build %s --native --langs %s", b.Context.MountPath, img, b.Context.RelDockerPath, lang))
+	// Run the Docker toolchain as the current user
+	uid := os.Getuid()
+	gid := os.Getgid()
+
+	outputLog, err := b.Config.CommandRunner.Run(fmt.Sprintf("docker run --rm --mount type=bind,source=%s,target=/usr/src/runnable -u %d:%d %s subo build %s --native --langs %s", b.Context.MountPath, uid, gid, img, b.Context.RelDockerPath, lang))
 
 	result.OutputLog = outputLog
 

builder/docker/rust/Dockerfile

@@ -1,11 +1,12 @@
 FROM suborbital/subo:dev as subo
 
 FROM rust:1.56.1-slim-buster
-WORKDIR /root/runnable
+WORKDIR /usr/src/runnable
 COPY --from=subo /go/bin/subo /usr/local/bin
 
-# install the wasm target and then install something that
-# doesn't exist (and ignore the error) to update the crates.io index
-RUN mkdir /root/suborbital && \
-    rustup target install wasm32-wasi
-RUN cargo install lazy_static; exit 0
+# install the wasm target and then force an update of the crates.io index
+RUN rustup target install wasm32-wasi && \
+    cargo search suborbital
+
+# make everything inside CARGO_HOME writable for anyone (again)
+RUN chmod -R a+w $RUSTUP_HOME $CARGO_HOME