ceph mon #5

Supports: xenial zesty trusty


Ceph is a distributed storage and network file system designed to provide excellent performance, reliability, and scalability.


Ceph is a distributed storage and network file system designed to provide excellent performance, reliability, and scalability.

This charm deploys a Ceph monitor cluster.


Boot things up by using:

juju deploy -n 3 ceph-mon

By default the ceph-mon cluster will not bootstrap until 3 service units have been deployed and started; this is to ensure that a quorum is achieved prior to adding storage devices.


This charm supports pausing and resuming ceph's health functions on a cluster, for example when doing maintenance on a machine. to pause or resume, call:

juju action do --unit ceph-mon/0 pause-health or juju action do --unit ceph-mon/0 resume-health

Scale Out Usage

You can use the Ceph OSD and Ceph Radosgw charms:

Rolling Upgrades

ceph-mon and ceph-osd charms have the ability to initiate a rolling upgrade. This is initiated by setting the config value for source. To perform a rolling upgrade first set the source for ceph-mon. Watch juju status. Once the monitor cluster is upgraded proceed to setting the ceph-osd source setting. Again watch juju status for output. The monitors and osds will sort themselves into a known order and upgrade one by one. As each server is upgrading the upgrade code will down all the monitor or osd processes on that server, apply the update and then restart them. You will notice in the juju status output that the servers will tell you which previous server they are waiting on.

Supported Upgrade Paths

Currently the following upgrade paths are supported using the Ubuntu Cloud Archive: - trusty-firefly -> trusty-hammer - trusty-hammer -> trusty-jewel

Firefly is available in Trusty, Hammer is in Trusty-Juno (end of life), Trusty-Kilo, Trusty-Liberty, and Jewel is available in Trusty-Mitaka.

For example if the current config source setting is: cloud:trusty-liberty changing that to cloud:trusty-mitaka will initiate a rolling upgrade of the monitor cluster from hammer to jewel.

Edge cases

There's an edge case in the upgrade code where if the previous node never starts upgrading itself then the rolling upgrade can hang forever. If you notice this has happened it can be fixed by setting the appropriate key in the ceph monitor cluster. The monitor cluster will have keys that look like ceph-mon_ip-ceph-mon-0_1484680239.573482_start and ceph-mon_ip-ceph-mon-0_1484680274.181742_stop. What each server is looking for is that stop key to indicate that the previous server upgraded successfully and it's safe to take itself down. If the stop key is not present it will wait 10 minutes, then consider that server dead and move on.

Network Space support

This charm supports the use of Juju Network Spaces, allowing the charm to be bound to network space configurations managed directly by Juju. This is only supported with Juju 2.0 and above.

Network traffic can be bound to specific network spaces using the public (front-side) and cluster (back-side) bindings:

juju deploy ceph-mon --bind "public=data-space cluster=cluster-space"

alternatively these can also be provided as part of a Juju native bundle configuration:

  charm: cs:xenial/ceph-mon
  num_units: 1
    public: data-space
    cluster: cluster-space

Please refer to the Ceph Network Reference for details on how using these options effects network traffic within a Ceph deployment.

NOTE: Spaces must be configured in the underlying provider prior to attempting to use them.

NOTE: Existing deployments using ceph-*-network configuration options will continue to function; these options are preferred over any network space binding provided if set.

NOTE: The monitor-hosts field is only used to migrate existing clusters to a juju managed solution and should be left blank otherwise.

Contact Information


Report bugs on Launchpad


Technical Footnotes

This charm uses the new-style Ceph deployment as reverse-engineered from the Chef cookbook at https://github.com/ceph/ceph-cookbooks, although we selected a different strategy to form the monitor cluster. Since we don't know the names or addresses of the machines in advance, we use the relation-joined hook to wait for all three nodes to come up, and then write their addresses to ceph.conf in the "mon host" parameter. After we initialize the monitor cluster a quorum forms quickly, and OSD bringup proceeds.

See the documentation for more information on Ceph monitor cluster deployment strategies and pitfalls.


(string) Which authentication flavour to use. . Valid options are "cephx" and "none". If "none" is specified, keys will still be created and deployed so that it can be enabled later.
(string) The IP address and netmask of the cluster (back-side) network (e.g., . If multiple networks are to be used, a space-delimited list of a.b.c.d/x can be provided.
(string) The IP address and netmask of the public (front-side) network (e.g., . If multiple networks are to be used, a space-delimited list of a.b.c.d/x can be provided.
(string) User provided Ceph configuration. Supports a string representation of a python dictionary where each top-level key represents a section in the ceph.conf template. You may only use sections supported in the template. . WARNING: this is not the recommended way to configure the underlying services that this charm installs and is used at the user's own risk. This option is mainly provided as a stop-gap for users that either want to test the effect of modifying some config or who have found a critical bug in the way the charm has configured their services and need it fixed immediately. We ask that whenever this is used, that the user consider opening a bug on this charm at http://bugs.launchpad.net/charms providing an explanation of why the config was needed so that we may consider it for inclusion as a natively supported config in the the charm.
(boolean) Setting this to true will tell Ceph to replicate across Juju's Availability Zone instead of specifically by host.
(int) Restrict the rbd features used to the specified level. If set, this will inform clients that they should set the config value `rbd default features`, for example: . rbd default features = 1 . This needs to be set to 1 when deploying a cloud with the nova-lxd hypervisor.
(int) Number of OSDs expected to be deployed in the cluster. This value is used for calculating the number of placement groups on pool creation. The number of placement groups for new pools are based on the actual number of OSDs in the cluster or the expected-osd-count, whichever is greater A value of 0 will cause the charm to only consider the actual number of OSDs in the cluster.
(string) The unique identifier (fsid) of the Ceph cluster. . To generate a suitable value use `uuidgen`. If left empty, an fsid will be generated. . NOTE: Changing this configuration after deployment is not supported and new service units will not be able to join the cluster.
(string) Apply system hardening. Supports a space-delimited list of modules to run. Supported modules currently include os, ssh, apache and mysql.
(string) Key ID to import to the apt keyring to support use with arbitary source configuration from outside of Launchpad archives or PPA's.
(int) Mon and OSD debug level. Max is 20.
(int) Number of ceph-mon units to wait for before attempting to bootstrap the monitor cluster. For production clusters the default value of 3 ceph-mon units is normally a good choice. . For test and development environments you can enable single-unit deployment by setting this to 1. . NOTE: To establish quorum and enable partition tolerance a odd number of ceph-mon units is required.
(string) A space-separated list of ceph mon hosts to use. This field is only used to migrate an existing cluster to a juju-managed solution and should otherwise be left unset.
(string) The Ceph secret key used by Ceph monitors. This value will become the mon.key. To generate a suitable value use: . ceph-authtool /dev/stdout --name=mon. --gen-key . If left empty, a secret key will be generated. . NOTE: Changing this configuration after deployment is not supported and new service units will not be able to join the cluster.
(string) Used by the nrpe-external-master subordinate charm. A string that will be prepended to instance name to set the hostname in nagios. So for instance the hostname would be something like: . juju-myservice-0 . If you're running multiple environments with the same services in them this allows you to differentiate between them.
(string) A comma-separated list of nagios servicegroups. If left empty, the nagios_context will be used as the servicegroup.
(boolean) Causes the charm to not do any of the initial bootstrapping of the Ceph monitor cluster. This is only intended to be used when migrating from the ceph all-in-one charm to a ceph-mon / ceph-osd deployment. Refer to the Charm Deployment guide at https://docs.openstack.org/charm-deployment-guide/latest/ for more information.
(int) The number of placement groups per OSD to target. It is important to properly size the number of placement groups per OSD as too many or too few placement groups per OSD may cause resource constraints and performance degradation. This value comes from the recommendation of the Ceph placement group calculator (http://ceph.com/pgcalc/) and recommended values are: . 100 - If the cluster OSD count is not expected to increase in the foreseeable future. 200 - If the cluster OSD count is expected to increase (up to 2x) in the foreseeable future. 300 - If the cluster OSD count is expected to increase between 2x and 3x in the foreseeable future.
(boolean) If True enables IPv6 support. The charm will expect network interfaces to be configured with an IPv6 address. If set to False (default) IPv4 is expected. . NOTE: these charms do not currently support IPv6 privacy extension. In order for this charm to function correctly, the privacy extension must be disabled and a non-temporary address must be configured/available on your network interface.
(string) Optional configuration to support use of additional sources such as: . - ppa:myteam/ppa - cloud:xenial-proposed/ocata - http://my.archive.com/ubuntu main . The last option should be used in conjunction with the key configuration option.
(string) YAML-formatted associative array of sysctl key/value pairs to be set persistently. By default we set pid_max, max_map_count and threads-max to a high value to avoid problems with large numbers (>20) of OSDs recovering. very large clusters should set those values even higher (e.g. max for kernel.pid_max is 4194303).
{ kernel.pid_max : 2097152, vm.max_map_count : 524288, kernel.threads-max: 2097152 }
(boolean) Configure use of direct IO for OSD journals.
(boolean) If set to True, supporting services will log to syslog.