Update Docker build process

This updates the Docker build process to account for all the recent
changes. We're also back to using a .dockerignore file again, as the
slowdown this used to introduced was fixed a while back.

Changelog: changed

.dockerignore

@@ -0,0 +1,11 @@
+.git/
+CHANGELOG.md
+clippy.toml
+deny.toml
+docs/
+gitlint
+libstd/build/
+macstadium.png
+scripts/
+target/
+tmp/

Dockerfile

@@ -1,28 +1,16 @@
 FROM alpine:3 AS builder
 
 RUN apk add --update make libffi libffi-dev rust cargo build-base
-
-# Per https://github.com/containers/buildah/issues/1849#issuecomment-635579332,
-# the presence of a .dockerignore slows down the build process. To work around
-# this, we add the necessary files/directories explicitly, instead of using
-# `ADD . /inko/` to add files.
-ADD Cargo.lock Cargo.toml LICENSE Makefile /inko/
-ADD .cargo /inko/.cargo/
-ADD ast /inko/ast/
-ADD bytecode /inko/bytecode/
-ADD compiler /inko/compiler/
-ADD libstd/src /inko/compiler/libstd/src
-ADD vm /inko/vm
-
+ADD . /inko/
 WORKDIR /inko
-RUN make build FEATURES='libffi-system' PREFIX='/usr'
+RUN make build FEATURES=libffi-system PREFIX='/usr'
 RUN strip target/release/inko
 RUN make install PREFIX='/usr'
 
 FROM alpine:3
 
 # libgcc is needed because libgcc is dynamically linked to the executable.
-RUN apk add --update libffi libffi-dev ruby ruby-json libgcc
+RUN apk add --update libffi libffi-dev libgcc
 
 COPY --from=builder ["/usr/bin/inko", "/usr/bin/inko"]
 COPY --from=builder ["/usr/lib/inko", "/usr/lib/inko/"]

Makefile

@@ -62,7 +62,7 @@ SOURCE_TAR := ${TMP_DIR}/${VERSION}.tar.gz
 MANIFEST := ${TMP_DIR}/manifest.txt
 
 build:
-	INKO_LIBSTD=${INSTALL_STD} cargo build --release
+	INKO_LIBSTD=${INSTALL_STD} cargo build --release ${FEATURES_OPTION}
 
 ${TMP_DIR}:
 	mkdir -p "${@}"
@@ -161,7 +161,7 @@ docs/versions:
 
 clippy:
 	touch */src/lib.rs */src/main.rs
-	cargo clippy ${FEATURES_OPTION} -- -D warnings
+	cargo clippy -- -D warnings
 
 rustfmt-check:
 	rustfmt --check */src/lib.rs */src/main.rs

docs/source/getting-started/installation.md

@@ -179,6 +179,12 @@ variable.
 When packaging Inko it's best to use a system wide installation of FFI, instead
 of building it from source when compiling Inko. To do so, build Inko as follows:
 
+```bash
+make build FEATURES=libffi-system
+```
+
+Or if you don't want to use make:
+
 ```bash
 cargo build --release --features libffi-system
 ```