Cross compilation for Raspberry PI

Adding cross compilation script based on https://github.com/rust-embedded/cross.
In order to the generated binary work on Raspbian, OpenSSL is linked statically.

This script required docker and will generate an image named
`rust-aws-ddns/base-armhf-img`.

Cargo.toml

@@ -7,6 +7,8 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+openssl = { version = "0.10", features = ["vendored"], optional = true }
+
 clap = "2.33"
 csv = "1.1"
 serde = { version = "1", features = ["derive"] }

Cross.toml

@@ -0,0 +1,2 @@
+[target.armv7-unknown-linux-gnueabihf]
+image = "rust-aws-ddns/base-armhf-img:latest"

cross-build.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+./docker/build-container-armhf.sh
+cross build --target armv7-unknown-linux-gnueabihf --features openssl

docker/Dockerfile-armhf

@@ -0,0 +1,12 @@
+FROM rustembedded/cross:armv7-unknown-linux-gnueabihf-0.2.1
+
+# libssl-dev:armhf && \
+
+RUN dpkg --add-architecture armhf && \
+    apt-get update && \
+    apt-get install --assume-yes \
+    openssl:armhf \
+    libssl-dev:armhf \
+    && rm -rf /var/lib/apt/lists/*
+
+ENV PKG_CONFIG_PATH=/usr/lib/arm-linux-gnueabihf/pkgconfig

docker/build-container-armhf.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+cd "$(dirname "$0")"
+docker build -t rust-aws-ddns/base-armhf-img -f Dockerfile-armhf .