Added parallel docker image multi-arch building

scripts/docker/build

@@ -1,13 +1,33 @@
 #!/bin/bash
+
 set -e
 
+PLATFORMS="linux/arm/v7,linux/arm64/v8,linux/amd64"
+# PLATFORMS="linux/amd64"
+DOCKER_IMAGE="shlinkio/shlink-web-client"
+BUILDX_VER=v0.4.1
+export DOCKER_CLI_EXPERIMENTAL=enabled
+
+mkdir -vp ~/.docker/cli-plugins/ ~/dockercache
+curl --silent -L "https://github.com/docker/buildx/releases/download/${BUILDX_VER}/buildx-${BUILDX_VER}.linux-amd64" > ~/.docker/cli-plugins/docker-buildx
+chmod a+x ~/.docker/cli-plugins/docker-buildx
+
+docker buildx create --use
+
 echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
 
 if [[ -z $TRAVIS_TAG ]]; then
-  docker build -t shlinkio/shlink-web-client:latest .
-  docker push shlinkio/shlink-web-client:latest
+  docker buildx build --push \
+    --platform ${PLATFORMS} \
+    -t ${DOCKER_IMAGE}:latest .
+
 else
-  docker build --build-arg VERSION=${TRAVIS_TAG#?} -t shlinkio/shlink-web-client:${TRAVIS_TAG#?} -t shlinkio/shlink-web-client:stable .
-  docker push shlinkio/shlink-web-client:${TRAVIS_TAG#?}
-  docker push shlinkio/shlink-web-client:stable
+  TAGS="-t ${DOCKER_IMAGE}:${TRAVIS_TAG#?}"
+  # Push stable tag only if this is not an alpha or beta release
+  [[ $TRAVIS_TAG != *"alpha"* && $TRAVIS_TAG != *"beta"* ]] && TAGS="${TAGS} -t ${DOCKER_IMAGE}:stable"
+
+  docker buildx build --push \
+    --build-arg SHLINK_VERSION=${TRAVIS_TAG#?} \
+    --platform ${PLATFORMS} \
+    ${TAGS} .
 fi

scripts/docker/install-docker

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+set -ex
+
+# install latest docker version
+curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
+apt-get update
+apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce
+
+# enable multiarch execution
+docker run --rm --privileged multiarch/qemu-user-static --reset -p yes