kas-docker: enable passing SSH configs

This commit enables passing the Docker container a directory containing
SSH configuration and optionally SSH identities and list of known SSH
hosts. Basically what you might expect to find in the ~/.ssh directory
of the container.

Signed-off-by: Silvano Cirujano Cuesta <silvano.cirujano-cuesta@siemens.com>
Suggested-by: Henning Schild <henning.schild@siemens.com>

kas-docker

@@ -40,6 +40,8 @@ usage()
 	printf "%b" "--docker-args\tAdditional arguments to pass to docker for" \
 		"running the build.\n"
 	printf "%b" "-v\t\tPrint operations.\n"
+	printf "%b" "--ssh-dir\tDirectory containing SSH configurations, " \
+		"avoid $HOME/.ssh unless you fully trust the container.\n"
 	exit 1
 }
 
@@ -87,6 +89,11 @@ while [ $# -gt 0 ]; do
 		USER_ARGS=$2
 		shift 2
 		;;
+	--ssh-dir)
+		[ $# -gt 2 ] || usage
+		SSH_DIR=$2
+		shift 2
+		;;
 	-v)
 		VERBOSE=1
 		shift 1
@@ -139,6 +146,11 @@ DOCKER_ARGS="-v ${REPO_DIR}:/repo:ro \
 	     -v ${KAS_WORK_DIR}:/work:rw --workdir=/work \
 	     -e USER_ID=$(id -u) -e GROUP_ID=$(id -g) --rm"
 
+if [ -n "${SSH_DIR}" ] ; then
+	[ -d "${SSH_DIR}" ] || echo "Passed SSH_VALUE '${SSH_DIR' is not a directory" ; exit 1
+	DOCKER_ARGS="${DOCKER_ARGS} -v $(readlink -f ${SSH_DIR}):/etc/skel/.ssh:ro"
+fi
+
 if [ -t 1 ]; then
 	DOCKER_ARGS="${DOCKER_ARGS} -t -i"
 fi