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diff --git a/doc/cephadm/host-management.rst b/doc/cephadm/host-management.rst new file mode 100644 index 000000000..df9525ca8 --- /dev/null +++ b/doc/cephadm/host-management.rst @@ -0,0 +1,436 @@ +.. _orchestrator-cli-host-management: + +=============== +Host Management +=============== + +Listing Hosts +============= + +Run a command of this form to list hosts associated with the cluster: + +.. prompt:: bash # + + ceph orch host ls [--format yaml] [--host-pattern <name>] [--label <label>] [--host-status <status>] + +In commands of this form, the arguments "host-pattern", "label" and +"host-status" are optional and are used for filtering. + +- "host-pattern" is a regex that matches against hostnames and returns only + matching hosts. +- "label" returns only hosts with the specified label. +- "host-status" returns only hosts with the specified status (currently + "offline" or "maintenance"). +- Any combination of these filtering flags is valid. It is possible to filter + against name, label and status simultaneously, or to filter against any + proper subset of name, label and status. + +.. _cephadm-adding-hosts: + +Adding Hosts +============ + +Hosts must have these :ref:`cephadm-host-requirements` installed. +Hosts without all the necessary requirements will fail to be added to the cluster. + +To add each new host to the cluster, perform two steps: + +#. Install the cluster's public SSH key in the new host's root user's ``authorized_keys`` file: + + .. prompt:: bash # + + ssh-copy-id -f -i /etc/ceph/ceph.pub root@*<new-host>* + + For example: + + .. prompt:: bash # + + ssh-copy-id -f -i /etc/ceph/ceph.pub root@host2 + ssh-copy-id -f -i /etc/ceph/ceph.pub root@host3 + +#. Tell Ceph that the new node is part of the cluster: + + .. prompt:: bash # + + ceph orch host add *<newhost>* [*<ip>*] [*<label1> ...*] + + For example: + + .. prompt:: bash # + + ceph orch host add host2 10.10.0.102 + ceph orch host add host3 10.10.0.103 + + It is best to explicitly provide the host IP address. If an IP is + not provided, then the host name will be immediately resolved via + DNS and that IP will be used. + + One or more labels can also be included to immediately label the + new host. For example, by default the ``_admin`` label will make + cephadm maintain a copy of the ``ceph.conf`` file and a + ``client.admin`` keyring file in ``/etc/ceph``: + + .. prompt:: bash # + + ceph orch host add host4 10.10.0.104 --labels _admin + +.. _cephadm-removing-hosts: + +Removing Hosts +============== + +A host can safely be removed from the cluster after all daemons are removed +from it. + +To drain all daemons from a host, run a command of the following form: + +.. prompt:: bash # + + ceph orch host drain *<host>* + +The ``_no_schedule`` label will be applied to the host. See +:ref:`cephadm-special-host-labels`. + +All OSDs on the host will be scheduled to be removed. You can check the progress of the OSD removal operation with the following command: + +.. prompt:: bash # + + ceph orch osd rm status + +See :ref:`cephadm-osd-removal` for more details about OSD removal. + +Use the following command to determine whether any daemons are still on the +host: + +.. prompt:: bash # + + ceph orch ps <host> + +After all daemons have been removed from the host, remove the host from the +cluster by running the following command: + +.. prompt:: bash # + + ceph orch host rm <host> + +Offline host removal +-------------------- + +Even if a host is offline and can not be recovered, it can be removed from the +cluster by running a command of the following form: + +.. prompt:: bash # + + ceph orch host rm <host> --offline --force + +.. warning:: This can potentially cause data loss. This command forcefully + purges OSDs from the cluster by calling ``osd purge-actual`` for each OSD. + Any service specs that still contain this host should be manually updated. + +.. _orchestrator-host-labels: + +Host labels +=========== + +The orchestrator supports assigning labels to hosts. Labels +are free form and have no particular meaning by itself and each host +can have multiple labels. They can be used to specify placement +of daemons. See :ref:`orch-placement-by-labels` + +Labels can be added when adding a host with the ``--labels`` flag: + +.. prompt:: bash # + + ceph orch host add my_hostname --labels=my_label1 + ceph orch host add my_hostname --labels=my_label1,my_label2 + +To add a label a existing host, run: + +.. prompt:: bash # + + ceph orch host label add my_hostname my_label + +To remove a label, run: + +.. prompt:: bash # + + ceph orch host label rm my_hostname my_label + + +.. _cephadm-special-host-labels: + +Special host labels +------------------- + +The following host labels have a special meaning to cephadm. All start with ``_``. + +* ``_no_schedule``: *Do not schedule or deploy daemons on this host*. + + This label prevents cephadm from deploying daemons on this host. If it is added to + an existing host that already contains Ceph daemons, it will cause cephadm to move + those daemons elsewhere (except OSDs, which are not removed automatically). + +* ``_no_autotune_memory``: *Do not autotune memory on this host*. + + This label will prevent daemon memory from being tuned even when the + ``osd_memory_target_autotune`` or similar option is enabled for one or more daemons + on that host. + +* ``_admin``: *Distribute client.admin and ceph.conf to this host*. + + By default, an ``_admin`` label is applied to the first host in the cluster (where + bootstrap was originally run), and the ``client.admin`` key is set to be distributed + to that host via the ``ceph orch client-keyring ...`` function. Adding this label + to additional hosts will normally cause cephadm to deploy config and keyring files + in ``/etc/ceph``. + +Maintenance Mode +================ + +Place a host in and out of maintenance mode (stops all Ceph daemons on host): + +.. prompt:: bash # + + ceph orch host maintenance enter <hostname> [--force] + ceph orch host maintenance exit <hostname> + +Where the force flag when entering maintenance allows the user to bypass warnings (but not alerts) + +See also :ref:`cephadm-fqdn` + +Rescanning Host Devices +======================= + +Some servers and external enclosures may not register device removal or insertion with the +kernel. In these scenarios, you'll need to perform a host rescan. A rescan is typically +non-disruptive, and can be performed with the following CLI command: + +.. prompt:: bash # + + ceph orch host rescan <hostname> [--with-summary] + +The ``with-summary`` flag provides a breakdown of the number of HBAs found and scanned, together +with any that failed: + +.. prompt:: bash [ceph:root@rh9-ceph1/]# + + ceph orch host rescan rh9-ceph1 --with-summary + +:: + + Ok. 2 adapters detected: 2 rescanned, 0 skipped, 0 failed (0.32s) + +Creating many hosts at once +=========================== + +Many hosts can be added at once using +``ceph orch apply -i`` by submitting a multi-document YAML file: + +.. code-block:: yaml + + service_type: host + hostname: node-00 + addr: 192.168.0.10 + labels: + - example1 + - example2 + --- + service_type: host + hostname: node-01 + addr: 192.168.0.11 + labels: + - grafana + --- + service_type: host + hostname: node-02 + addr: 192.168.0.12 + +This can be combined with service specifications (below) to create a cluster spec +file to deploy a whole cluster in one command. see ``cephadm bootstrap --apply-spec`` +also to do this during bootstrap. Cluster SSH Keys must be copied to hosts prior to adding them. + +Setting the initial CRUSH location of host +========================================== + +Hosts can contain a ``location`` identifier which will instruct cephadm to +create a new CRUSH host located in the specified hierachy. + +.. code-block:: yaml + + service_type: host + hostname: node-00 + addr: 192.168.0.10 + location: + rack: rack1 + +.. note:: + + The ``location`` attribute will be only affect the initial CRUSH location. Subsequent + changes of the ``location`` property will be ignored. Also, removing a host will no remove + any CRUSH buckets. + +See also :ref:`crush_map_default_types`. + +SSH Configuration +================= + +Cephadm uses SSH to connect to remote hosts. SSH uses a key to authenticate +with those hosts in a secure way. + + +Default behavior +---------------- + +Cephadm stores an SSH key in the monitor that is used to +connect to remote hosts. When the cluster is bootstrapped, this SSH +key is generated automatically and no additional configuration +is necessary. + +A *new* SSH key can be generated with: + +.. prompt:: bash # + + ceph cephadm generate-key + +The public portion of the SSH key can be retrieved with: + +.. prompt:: bash # + + ceph cephadm get-pub-key + +The currently stored SSH key can be deleted with: + +.. prompt:: bash # + + ceph cephadm clear-key + +You can make use of an existing key by directly importing it with: + +.. prompt:: bash # + + ceph config-key set mgr/cephadm/ssh_identity_key -i <key> + ceph config-key set mgr/cephadm/ssh_identity_pub -i <pub> + +You will then need to restart the mgr daemon to reload the configuration with: + +.. prompt:: bash # + + ceph mgr fail + +.. _cephadm-ssh-user: + +Configuring a different SSH user +---------------------------------- + +Cephadm must be able to log into all the Ceph cluster nodes as an user +that has enough privileges to download container images, start containers +and execute commands without prompting for a password. If you do not want +to use the "root" user (default option in cephadm), you must provide +cephadm the name of the user that is going to be used to perform all the +cephadm operations. Use the command: + +.. prompt:: bash # + + ceph cephadm set-user <user> + +Prior to running this the cluster SSH key needs to be added to this users +authorized_keys file and non-root users must have passwordless sudo access. + + +Customizing the SSH configuration +--------------------------------- + +Cephadm generates an appropriate ``ssh_config`` file that is +used for connecting to remote hosts. This configuration looks +something like this:: + + Host * + User root + StrictHostKeyChecking no + UserKnownHostsFile /dev/null + +There are two ways to customize this configuration for your environment: + +#. Import a customized configuration file that will be stored + by the monitor with: + + .. prompt:: bash # + + ceph cephadm set-ssh-config -i <ssh_config_file> + + To remove a customized SSH config and revert back to the default behavior: + + .. prompt:: bash # + + ceph cephadm clear-ssh-config + +#. You can configure a file location for the SSH configuration file with: + + .. prompt:: bash # + + ceph config set mgr mgr/cephadm/ssh_config_file <path> + + We do *not recommend* this approach. The path name must be + visible to *any* mgr daemon, and cephadm runs all daemons as + containers. That means that the file either need to be placed + inside a customized container image for your deployment, or + manually distributed to the mgr data directory + (``/var/lib/ceph/<cluster-fsid>/mgr.<id>`` on the host, visible at + ``/var/lib/ceph/mgr/ceph-<id>`` from inside the container). + +.. _cephadm-fqdn: + +Fully qualified domain names vs bare host names +=============================================== + +.. note:: + + cephadm demands that the name of the host given via ``ceph orch host add`` + equals the output of ``hostname`` on remote hosts. + +Otherwise cephadm can't be sure that names returned by +``ceph * metadata`` match the hosts known to cephadm. This might result +in a :ref:`cephadm-stray-host` warning. + +When configuring new hosts, there are two **valid** ways to set the +``hostname`` of a host: + +1. Using the bare host name. In this case: + +- ``hostname`` returns the bare host name. +- ``hostname -f`` returns the FQDN. + +2. Using the fully qualified domain name as the host name. In this case: + +- ``hostname`` returns the FQDN +- ``hostname -s`` return the bare host name + +Note that ``man hostname`` recommends ``hostname`` to return the bare +host name: + + The FQDN (Fully Qualified Domain Name) of the system is the + name that the resolver(3) returns for the host name, such as, + ursula.example.com. It is usually the hostname followed by the DNS + domain name (the part after the first dot). You can check the FQDN + using ``hostname --fqdn`` or the domain name using ``dnsdomainname``. + + .. code-block:: none + + You cannot change the FQDN with hostname or dnsdomainname. + + The recommended method of setting the FQDN is to make the hostname + be an alias for the fully qualified name using /etc/hosts, DNS, or + NIS. For example, if the hostname was "ursula", one might have + a line in /etc/hosts which reads + + 127.0.1.1 ursula.example.com ursula + +Which means, ``man hostname`` recommends ``hostname`` to return the bare +host name. This in turn means that Ceph will return the bare host names +when executing ``ceph * metadata``. This in turn means cephadm also +requires the bare host name when adding a host to the cluster: +``ceph orch host add <bare-name>``. + +.. + TODO: This chapter needs to provide way for users to configure + Grafana in the dashboard, as this is right now very hard to do. |