Allow to override Cirros image URL for air-gapped environments

Change-Id: I917b63ac93a7370e4e064a3fcce70820521387d4
Signed-off-by: Maksim Malchuk <[email protected]>
(cherry picked from commit b9c5fb3)

Author: mmalchuk

tools/init-runonce

@@ -21,7 +21,7 @@ fi
 ARCH=$(uname -m)
 CIRROS_RELEASE=${CIRROS_RELEASE:-0.6.2}
 IMAGE_PATH=/opt/cache/files/
-IMAGE_URL=https://github.com/cirros-dev/cirros/releases/download/${CIRROS_RELEASE}/
+IMAGE_URL=${IMAGE_URL:-"https://github.com/cirros-dev/cirros/releases/download/${CIRROS_RELEASE}/"}
 IMAGE=cirros-${CIRROS_RELEASE}-${ARCH}-disk.img
 IMAGE_NAME=cirros
 IMAGE_TYPE=linux