ceph/doc/cephadm/index.rst

.. _cephadm-bootstrap:

========================
 Installation (cephadm)
========================

.. note:: The *cephadm* bootstrap feature is first introduced in Octopus, and is not yet recommended for production deployments.

cephadm manages nodes in a cluster by establishing an SSH connection
and issues explicit management commands. It does not rely on
separate systems such as Rook or Ansible.

A new Ceph cluster is deployed by bootstrapping a cluster on a single
node, and then adding additional nodes and daemons via the CLI or GUI
dashboard.

The following example installs a basic three-node cluster. Each
node will be identified by its prompt. For example, "[monitor 1]"
identifies the first monitor, "[monitor 2]" identifies the second
monitor, and "[monitor 3]" identifies the third monitor. This
information is provided in order to make clear which commands
should be issued on which systems.

"[any node]" identifies any Ceph node, and in the context
of this installation guide means that the associated command
can be run on any node.

Requirements
============

- Podman or Docker
- LVM2

.. highlight:: console

Get cephadm
===========

The ``cephadm`` utility is used to bootstrap a new Ceph Cluster.

Use curl to fetch the standalone script::

  [monitor 1] # curl --silent --remote-name --location https://github.com/ceph/ceph/raw/master/src/cephadm/cephadm
  [monitor 1] # chmod +x cephadm
  
You can also get the utility by installing a package provided by
your Linux distribution::

   [monitor 1] # apt install -y cephadm   # or
   [monitor 1] # dnf install -y cephadm   # or
   [monitor 1] # yum install -y cephadm   # or
   [monitor 1] # zypper install -y cephadm


Bootstrap a new cluster
=======================

To create a new cluster, you need to know which *IP address* to use
for the cluster's first monitor.  This is normally just the IP for the
first cluster node.  If there are multiple networks and interfaces, be
sure to choose one that will be accessible by any hosts accessing the
Ceph cluster.

To bootstrap the cluster run the following command::

  [node 1] $ sudo ./cephadm bootstrap --mon-ip *<mon-ip>*

This command does a few things:

* Creates a monitor and manager daemon for the new cluster on the
  local host.  A minimal configuration file needed to communicate with
  the new cluster is written to ``ceph.conf`` in the local directory.
* A copy of the ``client.admin`` administrative (privileged!) secret
  key is written to ``ceph.client.admin.keyring`` in the local directory.
* Generates a new SSH key, and adds the public key to the local root user's
  ``/root/.ssh/authorized_keys`` file.  A copy of the public key is written
  to ``ceph.pub`` in the current directory.

Interacting with the cluster
============================

To interact with your cluster, start up a container that has all of 
the Ceph packages installed::

  [any node] $ sudo ./cephadm shell --config ceph.conf --keyring ceph.client.admin.keyring

The ``--config`` and ``--keyring`` arguments will bind those local
files to the default locations in ``/etc/ceph`` inside the container
to allow the ``ceph`` CLI utility to work without additional
arguments.  Inside the container, you can check the cluster status with::

  [ceph: root@monitor_1_hostname /]# ceph status

In order to interact with the Ceph cluster outside of a container
(that is, from the command line), install the Ceph
client packages and install the configuration and privileged 
administrator key in a global location::

   [any node] $ sudo apt install -y ceph-common   # or,
   [any node] $ sudo dnf install -y ceph-common   # or,
   [any node] $ sudo yum install -y ceph-common

   [any node] $ sudo install -m 0644 ceph.conf /etc/ceph/ceph.conf
   [any node] $ sudo install -m 0600 ceph.keyring /etc/ceph/ceph.keyring

Watching cephadm log messages
=============================

Cephadm logs to the ``cephadm`` cluster log channel, which means you can monitor progress in realtime with::

  # ceph -W cephadm

By default it will show info-level events and above.  To see
debug-level messages too::

  # ceph config set mgr mgr/cephadm/log_to_cluster_level debug
  # ceph -W cephadm --watch-debug

Be careful: the debug messages are very verbose!

You can see recent events with::

  # ceph log last cephadm

These events are also logged to the ``ceph.cephadm.log`` file on
monitor hosts and/or to the monitor-daemon stderr.

Adding hosts to the cluster
===========================

For each new host you'd like to add to the cluster, you need to do two things:

#. Install the cluster's public SSH key in the new host's root user's
   ``authorized_keys`` file.  This is easy with the ``ssh-copy-id`` script::

     [monitor 1] # ssh-copy-id -f -i ceph.pub root@*newhost*

#. Tell Ceph that the new node is part of the cluster::

     # ceph orch host add *newhost*

Deploying additional monitors
=============================

Normally a Ceph cluster has three or five monitor daemons spread
across different hosts.  As a rule of thumb, you should deploy five
monitors if there are five or more nodes in your cluster.

.. _CIDR: https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing#CIDR_notation

If all of your monitors will exist on the same IP subnet, cephadm can
automatically scale the number of monitors.  This subnet should be
specified in `CIDR`_ format (e.g., ``10.1.2.0/24``).  (If you do not
specify a subnet, you will need to manually specify an IP or subnet
when creating each monitor.)::

  # ceph config set mon public_network *<mon-cidr-network>*

For example::

  # ceph config set mon public_network 10.1.2.0/24

There are several ways to add additional monitors:

* You can simply tell cephadm how many monitors you want, and it will pick the
  hosts (randomly)::

    # ceph orch apply mon *<number-of-monitors>*

  For example, if you have 5 or more hosts added to the cluster,::

    # ceph orch apply mon 5

* You can explicitly specify which hosts to deploy on.  Be sure to include
  the first monitor host in this list.::

    # ceph orch apply mon *<host1,host2,host3,...>*

  For example,::

    # ceph orch apply mon host1,host2,host3

* You can control which hosts the monitors run on by adding the ``mon`` label
  to the appropriate hosts::

    # ceph orch host label add *<hostname>* mon

  To view the current hosts and labels,::

    # ceph orch host ls

  For example::

    # ceph orch host label add host1 mon
    # ceph orch host label add host2 mon
    # ceph orch host label add host3 mon
    # ceph orch host ls
    HOST   ADDR   LABELS  STATUS  
    host1         mon             
    host2         mon             
    host3         mon             
    host4
    host5

  Then tell cephadm to deploy monitors based on the label::

    # ceph orch apply mon label:mon

* You can explicitly specify the IP address or CIDR for each monitor
  and control where it is placed.  This is the only supported method
  if you did not specify the CIDR monitor network above.

  To deploy additional monitors,::

    # ceph orch daemon add mon *<host1:ip-or-network1> [<host1:ip-or-network-2>...]*

  For example, to deploy a second monitor on ``newhost1`` using an IP
  address ``10.1.2.123`` and a third monitor on ``newhost2`` in
  network ``10.1.2.0/24``,::

    # ceph orch daemon add mon newhost1:10.1.2.123
    # ceph orch daemon add mon newhost2:10.1.2.0/24

Deploying OSDs
==============

To add OSDs to the cluster, you have two options:

#. You need to know the device name for the block device (hard disk or
SSD) that will be used.  Then,::

     # ceph orch osd create *<host>*:*<path-to-device>*

   For example, to deploy an OSD on host *newhost*'s SSD,::

     # ceph orch osd create newhost:/dev/disk/by-id/ata-WDC_WDS200T2B0A-00SM50_182294800028


#. You need to describe your disk setup by it's properties (Drive Groups)

   Link to DriveGroup docs.::

    # ceph orch osd create -i my_drivegroups.yml


.. _drivegroups: drivegroups::

Deploying manager daemons
=========================

It is a good idea to have at least one backup manager daemon.  To
deploy one or more new manager daemons,::

  # ceph orch apply mgr *<new-num-mgrs>* [*<host1>* ...]

Deploying MDSs
==============

One or more MDS daemons is required to use the CephFS file system.
These are created automatically if the newer ``ceph fs volume``
interface is used to create a new file system.  For more information,
see :ref:`fs-volumes-and-subvolumes`.

To deploy metadata servers,::

  # ceph orch apply mds *<fs-name>* *<num-daemons>* [*<host1>* ...]

Deploying RGWs
==============

Cephadm deploys radosgw as a collection of daemons that manage a
particular *realm* and *zone*.  (For more information about realms and
zones, see :ref:`multisite`.)  To deploy a set of radosgw daemons for
a particular realm and zone,::

  # ceph orch apply rgw *<realm-name>* *<zone-name>* *<num-daemons>* [*<host1>* ...]

Note that with cephadm, radosgw daemons are configured via the monitor
configuration database instead of via a `ceph.conf` or the command line.  If
that confiruation isn't already in place (usually in the
``client.rgw.<realmname>.<zonename>`` section), then the radosgw
daemons will start up with default settings (e.g., binding to port
80).


Further Reading
===============

.. toctree::
    :maxdepth: 2

    Cephadm administration <administration>
    Cephadm monitoring <monitoring>
    Cephadm CLI <../mgr/orchestrator>
    DriveGroups <drivegroups>
    OS recommendations <../start/os-recommendations>