Optimize release workflow.

- Split Debian and Alpine into different build matrix
  This starts building both Debian and Alpine based images at the same time
- Make use of Docker BuildKit, which improves speed also.
- Use BuildKit caching for Rust Cargo across docker images.
  This prevents downloading the same crates multiple times.
- Use Github Actions Services to start a docker registry, starting it
via the build script sometimes caused issues.
- Updated the Build workflow to use Ubuntu 20.04 which is more close to
the Bullseye Debian release regarding package versions.

docker/armv6/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker/dockerfile:1
+
 # This file was generated using a Jinja2 template.
 # Please make your changes in `Dockerfile.j2` and then `make` the individual Dockerfiles.
 
@@ -31,15 +33,27 @@ FROM rust:1.54-bullseye as build
 ARG DB=sqlite,mysql,postgresql
 
 # Build time options to avoid dpkg warnings and help with reproducible builds.
-ENV DEBIAN_FRONTEND=noninteractive LANG=C.UTF-8 TZ=UTC TERM=xterm-256color
+ENV DEBIAN_FRONTEND=noninteractive \
+    LANG=C.UTF-8 \
+    TZ=UTC \
+    TERM=xterm-256color \
+    CARGO_HOME="/root/.cargo" \
+    USER="root"
 
-# Don't download rust docs
-RUN rustup set profile minimal
 
+# Create CARGO_HOME folder and don't download rust docs
+RUN mkdir -pv "${CARGO_HOME}" \
+    && rustup set profile minimal
+
+# NOTE: Any apt-get/dpkg after this stage will fail because of broken dependencies.
+# For Diesel-RS migrations_macros to compile with MySQL/MariaDB we need to do some magic.
+# We at least need libmariadb3:amd64 installed for the x86_64 version of libmariadb.so (client)
+# We also need the libmariadb-dev-compat:amd64 but it can not be installed together with the :armel version.
+# What we can do is a force install, because nothing important is overlapping each other.
+#
 # Install required build libs for armel architecture.
 # To compile both mysql and postgresql we need some extra packages for both host arch and target arch
-RUN sed 's/^deb/deb-src/' /etc/apt/sources.list > \
-        /etc/apt/sources.list.d/deb-src.list \
+RUN sed 's/^deb/deb-src/' /etc/apt/sources.list > /etc/apt/sources.list.d/deb-src.list \
     && dpkg --add-architecture armel \
     && apt-get update \
     && apt-get install -y \
@@ -48,16 +62,35 @@ RUN sed 's/^deb/deb-src/' /etc/apt/sources.list > \
         libc6-dev:armel \
         libpq5:armel \
         libpq-dev \
+        libmariadb3:amd64 \
         libmariadb-dev:armel \
         libmariadb-dev-compat:armel \
         gcc-arm-linux-gnueabi \
-    && mkdir -p ~/.cargo \
-    && echo '[target.arm-unknown-linux-gnueabi]' >> ~/.cargo/config \
-    && echo 'linker = "arm-linux-gnueabi-gcc"' >> ~/.cargo/config \
-    && echo 'rustflags = ["-L/usr/lib/arm-linux-gnueabi"]' >> ~/.cargo/config
+    #
+    # Manual install libmariadb-dev-compat:amd64 ( After this broken dependencies will break apt )
+    && apt-get download libmariadb-dev-compat:amd64 \
+    && dpkg --force-all -i ./libmariadb-dev-compat*.deb \
+    && rm -rvf ./libmariadb-dev-compat*.deb \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/* \
+    #
+    # For Diesel-RS migrations_macros to compile with PostgreSQL we need to do some magic.
+    # The libpq5:armel package seems to not provide a symlink to libpq.so.5 with the name libpq.so.
+    # This is only provided by the libpq-dev package which can't be installed for both arch at the same time.
+    # Without this specific file the ld command will fail and compilation fails with it.
+    && ln -sfnr /usr/lib/arm-linux-gnueabi/libpq.so.5 /usr/lib/arm-linux-gnueabi/libpq.so \
+    #
+    # Make sure cargo has the right target config
+    && echo '[target.arm-unknown-linux-gnueabi]' >> "${CARGO_HOME}/config" \
+    && echo 'linker = "arm-linux-gnueabi-gcc"' >> "${CARGO_HOME}/config" \
+    && echo 'rustflags = ["-L/usr/lib/arm-linux-gnueabi"]' >> "${CARGO_HOME}/config"
+
+# Set arm specific environment values
+ENV CC_arm_unknown_linux_gnueabi="/usr/bin/arm-linux-gnueabi-gcc"
+ENV CROSS_COMPILE="1"
+ENV OPENSSL_INCLUDE_DIR="/usr/include/arm-linux-gnueabi"
+ENV OPENSSL_LIB_DIR="/usr/lib/arm-linux-gnueabi"
 
-ENV CARGO_HOME "/root/.cargo"
-ENV USER "root"
 
 # Creates a dummy project used to grab dependencies
 RUN USER=root cargo new --bin /app
@@ -68,25 +101,6 @@ COPY ./Cargo.* ./
 COPY ./rust-toolchain ./rust-toolchain
 COPY ./build.rs ./build.rs
 
-# NOTE: This should be the last apt-get/dpkg for this stage, since after this it will fail because of broken dependencies.
-# For Diesel-RS migrations_macros to compile with MySQL/MariaDB we need to do some magic.
-# We at least need libmariadb3:amd64 installed for the x86_64 version of libmariadb.so (client)
-# We also need the libmariadb-dev-compat:amd64 but it can not be installed together with the :armel version.
-# What we can do is a force install, because nothing important is overlapping each other.
-RUN apt-get install -y --no-install-recommends libmariadb3:amd64 \
-    && apt-get download libmariadb-dev-compat:amd64 \
-    && dpkg --force-all -i ./libmariadb-dev-compat*.deb \
-    && rm -rvf ./libmariadb-dev-compat*.deb \
-    # For Diesel-RS migrations_macros to compile with PostgreSQL we need to do some magic.
-    # The libpq5:armel package seems to not provide a symlink to libpq.so.5 with the name libpq.so.
-    # This is only provided by the libpq-dev package which can't be installed for both arch at the same time.
-    # Without this specific file the ld command will fail and compilation fails with it.
-    && ln -sfnr /usr/lib/arm-linux-gnueabi/libpq.so.5 /usr/lib/arm-linux-gnueabi/libpq.so
-
-ENV CC_arm_unknown_linux_gnueabi="/usr/bin/arm-linux-gnueabi-gcc"
-ENV CROSS_COMPILE="1"
-ENV OPENSSL_INCLUDE_DIR="/usr/include/arm-linux-gnueabi"
-ENV OPENSSL_LIB_DIR="/usr/lib/arm-linux-gnueabi"
 RUN rustup target add arm-unknown-linux-gnueabi
 
 # Builds your dependencies and removes the
@@ -128,6 +142,7 @@ RUN mkdir /data \
     dumb-init \
     libmariadb-dev-compat \
     libpq5 \
+    && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
 # hadolint ignore=DL3059