vstart.sh: only extract first container digest

Otherwise the container_image value includes the same hash twice, separated
by a newline, causing all sorts of confusion.

Signed-off-by: Sage Weil <sage@newdream.net>
(cherry picked from commit 6741082eb3e03db608899a8a5fef44fb05d356b7)

diff --git a/src/vstart.sh b/src/vstart.sh
index 21f26b851a11b8eb4ba3ad12670157e46ee26cb7..e1227def7a5782e0e6f5b746fd849b6def8e2597 100755 (executable)
--- a/src/vstart.sh
+++ b/src/vstart.sh
@@ -1036,7 +1036,7 @@ EOF
        if [ "$new" -eq 1 ]; then
                digest=$(curl -s \
                https://registry.hub.docker.com/v2/repositories/ceph/daemon-base/tags/latest-master-devel \
-               | jq -r '.images[].digest')
+               | jq -r '.images[0].digest')
                ceph_adm config set global container_image "docker.io/ceph/daemon-base@$digest"
        fi
         ceph_adm config-key set mgr/cephadm/ssh_identity_key -i ~/.ssh/id_rsa