Check docker-compose version

Signed-off-by: Simó Albert i Beltran <sim6@bona.gent>

dd-ctl

@@ -2,6 +2,21 @@
 
 OPERATION="$1"
 
+# We need docker-compose >= 1.28 to catch configuration variables
+REQUIRED_DOCKER_COMPOSE_VERSION="1.28"
+
+docker_compose_version(){
+	docker-compose --version --short | sed 's/^docker-compose version \([^,]\+\),.*$/\1/'
+}
+
+check_docker_compose_version(){
+	# We cannot use sort -C because is not included in BusyBox v1.33.1 of docker:dind image
+	{
+		echo "$REQUIRED_DOCKER_COMPOSE_VERSION"
+		docker_compose_version
+	} | sort -c -V 2> /dev/null
+}
+
 help() {
 	cat <<-EOF
 	 Example: ./dd.ctl [operation] [arguments]
@@ -51,6 +66,11 @@ if [ "$OPERATION" != "prerequisites" ]; then
 		echo "You need to copy digitaldemocratic.conf.sample to digitaldemocratic.conf and adapt"
 		exit 1
 	fi
+	if ! check_docker_compose_version
+	then
+		echo "ERROR: Please use docker-compose greather than or equal to $REQUIRED_DOCKER_COMPOSE_VERSION." >&2
+		exit 1
+	fi
 fi
 
 BRANCH="${2:-master}"