This Dockerfile creates a Ceph metadata server (MDS) image
The environment variable MDS_NAME is required. It describes the name of the MDS
For example:
docker run -e MDS_NAME=mymds ceph/mds
It will look for either /etc/ceph/ceph.client.admin.keyring or /etc/ceph/ceph.mds.keyring with which to authenticate. You can get ceph.client.admin.keyring from another ceph node.
Commonly, you will want to bind-mount your host's /etc/ceph into the container. For example:
docker run -e MDS_NAME=mymds -v /etc/ceph:/etc/ceph ceph/mds
By default, the MDS does NOT create a ceph filesystem. If you wish to have this MDS create a ceph filesystem (it will only do this if the specified CEPHFS_NAME does not already exist), you must set, at a minimum, CEPHFS_CREATE=1. It is strongly recommended that you read the rest of this section, as well.
For most people, the defaults for the following optional environment variables are fine, but if you wish to customize the data and metadata pools in which your CephFS is stored, you may override the following as you wish:
CEPHFS_CREATE: Whether to create the ceph filesystem (0 = no / 1 = yes), if it doesn't exist. Defaults to 0 (no)CEPHFS_NAME: The name of the new ceph filesystem and the basis on which the later variables are created. Defaults tocephfsCEPHFS_DATA_POOL: The name of the data pool for the ceph filesystem. If it does not exist, it will be created. Defaults to${CEPHFS_NAME}_dataCEPHFS_DATA_POOL_PG: The number of placement groups for the data pool. Defaults to8CEPHFS_METADATA_POOL: The name of the metadata pool for the ceph filesystem. If it does not exist, it will be created. Defaults to${CEPHFS_NAME}_metadataCEPHFS_METADATA_POOL_PG: The number of placement groups for the metadata pool. Defaults to8
ceph/mds seems to die most of the time when trying to start it. Trying repeatedly will eventually get it to run. If run manually within the container (enrtypoint to base, then manually run entrypoint.sh), it fails less often, but still frequently (though less than 50% of the time).