.. _orchestrator-cli-host-management: =============== Host Management =============== To list hosts associated with the cluster: .. prompt:: bash # ceph orch host ls [--format yaml] .. _cephadm-adding-hosts: Adding Hosts ============ 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@** 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* For example: .. prompt:: bash # ceph orch host add host2 ceph orch host add host3 .. _cephadm-removing-hosts: Removing Hosts ============== If the node that want you to remove is running OSDs, make sure you remove the OSDs from the node. To remove a host from a cluster, do the following: For all Ceph service types, except for ``node-exporter`` and ``crash``, remove the host from the placement specification file (for example, cluster.yml). For example, if you are removing the host named host2, remove all occurrences of ``- host2`` from all ``placement:`` sections. Update: .. code-block:: yaml service_type: rgw placement: hosts: - host1 - host2 To: .. code-block:: yaml service_type: rgw placement: hosts: - host1 Remove the host from cephadm's environment: .. prompt:: bash # ceph orch host rm host2 If the host is running ``node-exporter`` and crash services, remove them by running the following command on the host: .. prompt:: bash # cephadm rm-daemon --fsid CLUSTER_ID --name SERVICE_NAME .. _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` To add a label, run:: ceph orch host label add my_hostname my_label To remove a label, run:: ceph orch host label rm my_hostname my_label Maintenance Mode ================ Place a host in and out of maintenance mode (stops all Ceph daemons on host):: ceph orch host maintenance enter [--force] ceph orch host maintenace exit Where the force flag when entering maintenance allows the user to bypass warnings (but not alerts) See also :ref:`cephadm-fqdn` Host Specification ================== Many hosts can be added at once using ``ceph orch apply -i`` by submitting a multi-document YAML file:: --- service_type: host addr: node-00 hostname: node-00 labels: - example1 - example2 --- service_type: host addr: node-01 hostname: node-01 labels: - grafana --- service_type: host addr: node-02 hostname: node-02 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. 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:: ceph cephadm generate-key The public portion of the SSH key can be retrieved with:: ceph cephadm get-pub-key The currently stored SSH key can be deleted with:: ceph cephadm clear-key You can make use of an existing key by directly importing it with:: ceph config-key set mgr/cephadm/ssh_identity_key -i ceph config-key set mgr/cephadm/ssh_identity_pub -i You will then need to restart the mgr daemon to reload the configuration with:: ceph mgr fail 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:: ceph cephadm set-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:: ceph cephadm set-ssh-config -i To remove a customized SSH config and revert back to the default behavior:: ceph cephadm clear-ssh-config #. You can configure a file location for the SSH configuration file with:: ceph config set mgr mgr/cephadm/ssh_config_file 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//mgr.`` on the host, visible at ``/var/lib/ceph/mgr/ceph-`` from inside the container). .. _cephadm-fqdn: Fully qualified domain names vs bare host names =============================================== cephadm has very minimal requirements when it comes to resolving host names etc. When cephadm initiates an ssh connection to a remote host, the host name can be resolved in four different ways: - a custom ssh config resolving the name to an IP - via an externally maintained ``/etc/hosts`` - via explicitly providing an IP address to cephadm: ``ceph orch host add `` - automatic name resolution via DNS. Ceph itself uses the command ``hostname`` to determine the name of the current host. .. 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, the host 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 ``. .. TODO: This chapter needs to provide way for users to configure Grafana in the dashboard, as this is right no very hard to do.