on arm, install docker-compose via pip

Sadly, there's no binary distribution for linux+arm yet:
docker/compose#7472

This is an imperfect solution, but it gets us going for now.

packer/linux/conf/buildkite-agent/hooks/environment

@@ -9,6 +9,11 @@ BUILDKITE_DOCKER_CONFIG_TEMP_DIRECTORY=$(mktemp -d)
 export BUILDKITE_DOCKER_CONFIG_TEMP_DIRECTORY
 export DOCKER_CONFIG="$BUILDKITE_DOCKER_CONFIG_TEMP_DIRECTORY"
 
+# on linux/arm64 we have to install docker-compose via pip, which
+# has a dependency on the cryptography package, which requires some
+# convincing to run with the version of openssl distributed with Amazon Linux 2
+export CRYPTOGRAPHY_ALLOW_OPENSSL_102=true
+
 echo "~~~ :llama: Setting up elastic stack environment ($BUILDKITE_STACK_VERSION)"
 cat ~/cfn-env
 

packer/linux/scripts/install-docker.sh

@@ -36,6 +36,10 @@ if [ ${MACHINE} == "x86_64" ]; then
 	sudo curl -Lsf -o /usr/bin/docker-compose https://github.com/docker/compose/releases/download/${DOCKER_COMPOSE_VERSION}/docker-compose-Linux-x86_64
 	sudo chmod +x /usr/bin/docker-compose
 	docker-compose --version
+elif [[ ${MACHINE} == "aarch64" ]]; then
+  sudo yum install -y gcc-c++ libffi-devel openssl-devel python3-devel
+  sudo pip3 install docker-compose
+	CRYPTOGRAPHY_ALLOW_OPENSSL_102=true docker-compose version
 fi
 
 echo "Adding docker cron tasks..."