ARMV7 Docker Image (#234)

* feat: Push dockerfile.

Progress on trying to get armv7 image.

* feat: Add Dockerfile.

Using rust:slim as builder image.

* refactor: Changes to build for armv7.

* feat: Add .cargo config.

Taken from: https://medium.com/swlh/compiling-rust-for-raspberry-pi-arm-922b55dbb050

* refactor: Add environment variable for linker.

Instead of .cargo config file.

* feat: Working cross compile version.

For Armv7.

* refactor: Clean up dockerfile.

* refactor: Rename to armv7.

Rename Dockerfile.armv7rust to Dockerfile.armv7.

* feat: Add workflow to build ARMv7 docker image.

* docs: Add armv7 deployment instructions.

Dockerfile.armv7

@@ -0,0 +1,43 @@
+####################################################################################################
+## Builder
+####################################################################################################
+FROM --platform=$BUILDPLATFORM rust:slim AS builder
+
+ENV CARGO_TARGET_ARMV7_UNKNOWN_LINUX_MUSLEABIHF_LINKER=arm-linux-gnueabihf-gcc
+ENV CC_armv7_unknown_linux_musleabihf=arm-linux-gnueabihf-gcc
+
+RUN apt-get update && apt-get -y install gcc-arm-linux-gnueabihf \
+    binutils-arm-linux-gnueabihf \
+    musl-tools
+
+RUN rustup target add armv7-unknown-linux-musleabihf
+
+WORKDIR /libreddit
+
+COPY . .
+
+RUN cargo build --target armv7-unknown-linux-musleabihf --release
+
+####################################################################################################
+## Final image
+####################################################################################################
+FROM alpine:latest
+
+# Import ca-certificates from builder
+COPY --from=builder /usr/share/ca-certificates /usr/share/ca-certificates
+COPY --from=builder /etc/ssl/certs /etc/ssl/certs
+
+# Copy our build
+COPY --from=builder /libreddit/target/armv7-unknown-linux-musleabihf/release/libreddit /usr/local/bin/libreddit
+
+# Use an unprivileged user.
+RUN adduser --home /nonexistent --no-create-home --disabled-password libreddit
+USER libreddit
+
+# Tell Docker to expose port 8080
+EXPOSE 8080
+
+# Run a healthcheck every minute to make sure Libreddit is functional
+HEALTHCHECK --interval=1m --timeout=3s CMD wget --spider --q http://localhost:8080/settings || exit 1
+
+CMD ["libreddit"]