zypper install -y cephadm
curl-based installation
First, determine what version of Ceph you will need. You can use the releases
page to find the latest active releases.
For example, we might look at that page and find that 18.2.0 is the latest
active release.
Use curl to fetch a build of cephadm for that release.
CEPH_RELEASE=18.2.0 # replace this with the active release
curl --silent --remote-name --location https://download.ceph.com/rpm-${CEPH_RELEASE}/el9/noarch/cephadm
Ensure the cephadm file is executable:
This file can be run directly from the current directory:
./cephadm <arguments...>
If you encounter any issues with running cephadm due to errors including
the message bad interpreter, then you may not have Python or
the correct version of Python installed. The cephadm tool requires Python 3.6
and above. You can manually run cephadm with a particular version of Python by
prefixing the command with your installed Python version. For example:
python3.8 ./cephadm <arguments...>
Although the standalone cephadm is sufficient to get a cluster started, it is
convenient to have the cephadm command installed on the host. To install
the packages that provide the cephadm command, run the following
commands:
./cephadm add-repo --release reef
./cephadm install
Confirm that cephadm is now in your PATH by running which:
A successful which cephadm command will return this:
/usr/sbin/cephadm
What to know before you bootstrap
The first step in creating a new Ceph cluster is running the cephadm
bootstrap command on the Ceph cluster’s first host. The act of running the
cephadm bootstrap command on the Ceph cluster’s first host creates the Ceph
cluster’s first “monitor daemon”, and that monitor daemon needs an IP address.
You must pass the IP address of the Ceph cluster’s first host to the ceph
bootstrap command, so you’ll need to know the IP address of that host.
Important
ssh must be installed and running in order for the
bootstrapping procedure to succeed.
If there are multiple networks and interfaces, be sure to choose one
that will be accessible by any host accessing the Ceph cluster.
Running the bootstrap command
Run the ceph bootstrap command:
cephadm bootstrap --mon-ip *<mon-ip>*
This command will:
Create a monitor and manager daemon for the new cluster on the local
host.
Generate a new SSH key for the Ceph cluster and add it to the root
user’s /root/.ssh/authorized_keys file.
Write a copy of the public key to /etc/ceph/ceph.pub.
Write a minimal configuration file to /etc/ceph/ceph.conf. This
file is needed to communicate with the new cluster.
Write a copy of the client.admin administrative (privileged!)
secret key to /etc/ceph/ceph.client.admin.keyring.
Add the _admin label to the bootstrap host. By default, any host
with this label will (also) get a copy of /etc/ceph/ceph.conf and
/etc/ceph/ceph.client.admin.keyring.
Further information about cephadm bootstrap
The default bootstrap behavior will work for most users. But if you’d like
immediately to know more about cephadm bootstrap, read the list below.
Also, you can run cephadm bootstrap -h to see all of cephadm’s
available options.
By default, Ceph daemons send their log output to stdout/stderr, which is picked
up by the container runtime (docker or podman) and (on most systems) sent to
journald. If you want Ceph to write traditional log files to /var/log/ceph/$fsid,
use the --log-to-file option during bootstrap.
Larger Ceph clusters perform better when (external to the Ceph cluster)
public network traffic is separated from (internal to the Ceph cluster)
cluster traffic. The internal cluster traffic handles replication, recovery,
and heartbeats between OSD daemons. You can define the cluster
network by supplying the --cluster-network option to the bootstrap
subcommand. This parameter must define a subnet in CIDR notation (for example
10.90.90.0/24 or fe80::/64).
cephadm bootstrap writes to /etc/ceph the files needed to access
the new cluster. This central location makes it possible for Ceph
packages installed on the host (e.g., packages that give access to the
cephadm command line interface) to find these files.
Daemon containers deployed with cephadm, however, do not need
/etc/ceph at all. Use the --output-dir *<directory>* option
to put them in a different directory (for example, .). This may help
avoid conflicts with an existing Ceph configuration (cephadm or
otherwise) on the same host.
You can pass any initial Ceph configuration options to the new
cluster by putting them in a standard ini-style configuration file
and using the --config *<config-file>* option. For example:
$ cat <<EOF > initial-ceph.conf
[global]
osd crush chooseleaf type = 0
$ ./cephadm bootstrap --config initial-ceph.conf ...
The --ssh-user *<user>* option makes it possible to choose which SSH
user cephadm will use to connect to hosts. The associated SSH key will be
added to /home/*<user>*/.ssh/authorized_keys
. The user that you
designate with this option must have passwordless sudo access.
If you are using a container on an authenticated registry that requires
login, you may add the argument:
--registry-json <path to json file>
example contents of JSON file with login info:
{"url":"REGISTRY_URL", "username":"REGISTRY_USERNAME", "password":"REGISTRY_PASSWORD"}
Cephadm will attempt to log in to this registry so it can pull your container
and then store the login info in its config database. Other hosts added to
the cluster will then also be able to make use of the authenticated registry.
See Different deployment scenarios for additional examples for using cephadm bootstrap.
Enable Ceph CLI
Cephadm does not require any Ceph packages to be installed on the
host. However, we recommend enabling easy access to the ceph
command. There are several ways to do this:
The cephadm shell command launches a bash shell in a container
with all of the Ceph packages installed. By default, if
configuration and keyring files are found in /etc/ceph on the
host, they are passed into the container environment so that the
shell is fully functional. Note that when executed on a MON host,
cephadm shell will infer the config from the MON container
instead of using the default configuration. If --mount <path>
is given, then the host <path> (file or directory) will appear
under /mnt inside the container:
cephadm shell
To execute ceph commands, you can also run commands like this:
cephadm shell -- ceph -s
You can install the ceph-common package, which contains all of the
ceph commands, including ceph, rbd, mount.ceph (for mounting
CephFS file systems), etc.:
cephadm add-repo --release reef
cephadm install ceph-common
Confirm that the ceph command is accessible with:
Confirm that the ceph command can connect to the cluster and also
its status with:
ceph status
Adding Hosts
Add all hosts to the cluster by following the instructions in
Adding Hosts.
By default, a ceph.conf file and a copy of the client.admin keyring are
maintained in /etc/ceph on all hosts that have the _admin label. This
label is initially applied only to the bootstrap host. We usually recommend
that one or more other hosts be given the _admin label so that the Ceph CLI
(for example, via cephadm shell) is easily accessible on multiple hosts. To add
the _admin label to additional host(s), run a command of the following form:
ceph orch host label add *<host>* _admin
Adding additional MONs
A typical Ceph cluster has three or five monitor daemons spread
across different hosts. We recommend deploying five
monitors if there are five or more nodes in your cluster.
Please follow Deploying additional monitors to deploy additional MONs.
Adding Storage
To add storage to the cluster, you can tell Ceph to consume any
available and unused device(s):
ceph orch apply osd --all-available-devices
See Deploy OSDs for more detailed instructions.
Enabling OSD memory autotuning
Warning
By default, cephadm enables osd_memory_target_autotune on bootstrap, with mgr/cephadm/autotune_memory_target_ratio set to .7 of total host memory.
See Automatically tuning OSD memory.
To deploy hyperconverged Ceph with TripleO, please refer to the TripleO documentation: Scenario: Deploy Hyperconverged Ceph
In other cases where the cluster hardware is not exclusively used by Ceph (hyperconverged),
reduce the memory consumption of Ceph like so:
# hyperconverged only:
ceph config set mgr mgr/cephadm/autotune_memory_target_ratio 0.2
Then enable memory autotuning:
ceph config set osd osd_memory_target_autotune true
Using Ceph
To use the Ceph Filesystem, follow Deploy CephFS.
To use the Ceph Object Gateway, follow Deploy RGWs.
To use NFS, follow NFS Service
To use iSCSI, follow Deploying iSCSI
Different deployment scenarios
Single host
To configure a Ceph cluster to run on a single host, use the
--single-host-defaults flag when bootstrapping. For use cases of this, see
One Node Cluster.
The --single-host-defaults flag sets the following configuration options:
global/osd_crush_chooseleaf_type = 0
global/osd_pool_default_size = 2
mgr/mgr_standby_modules = False
For more information on these options, see One Node Cluster and
mgr_standby_modules in ceph-mgr administrator’s guide.
Deployment in an isolated environment
You might need to install cephadm in an environment that is not connected
directly to the internet (such an environment is also called an “isolated
environment”). This can be done if a custom container registry is used. Either
of two kinds of custom container registry can be used in this scenario: (1) a
Podman-based or Docker-based insecure registry, or (2) a secure registry.
The practice of installing software on systems that are not connected directly
to the internet is called “airgapping” and registries that are not connected
directly to the internet are referred to as “airgapped”.
Make sure that your container image is inside the registry. Make sure that you
have access to all hosts that you plan to add to the cluster.
Run a local container registry:
podman run --privileged -d --name registry -p 5000:5000 -v /var/lib/registry:/var/lib/registry --restart=always registry:2
If you are using an insecure registry, configure Podman or Docker with the
hostname and port where the registry is running.
You must repeat this step for every host that accesses the local
insecure registry.
Push your container image to your local registry. Here are some acceptable
kinds of container images:
Ceph container image. See Ceph Container Images.
Prometheus container image
Node exporter container image
Grafana container image
Alertmanager container image
Create a temporary configuration file to store the names of the monitoring
images. (See Using custom images):
cat <<EOF > initial-ceph.conf
[mgr]
mgr/cephadm/container_image_prometheus = *<hostname>*:5000/prometheus
mgr/cephadm/container_image_node_exporter = *<hostname>*:5000/node_exporter
mgr/cephadm/container_image_grafana = *<hostname>*:5000/grafana
mgr/cephadm/container_image_alertmanager = *<hostname>*:5000/alertmanger
Run bootstrap using the --image flag and pass the name of your
container image as the argument of the image flag. For example:
cephadm --image *<hostname>*:5000/ceph/ceph bootstrap --mon-ip *<mon-ip>*
Deployment with custom SSH keys
Bootstrap allows users to create their own private/public SSH key pair
rather than having cephadm generate them automatically.
To use custom SSH keys, pass the --ssh-private-key and --ssh-public-key
fields to bootstrap. Both parameters require a path to the file where the
keys are stored:
cephadm bootstrap --mon-ip <ip-addr> --ssh-private-key <private-key-filepath> --ssh-public-key <public-key-filepath>
This setup allows users to use a key that has already been distributed to hosts
the user wants in the cluster before bootstrap.
In order for cephadm to connect to other hosts you’d like to add
to the cluster, make sure the public key of the key pair provided is set up
as an authorized key for the ssh user being used, typically root. If you’d
like more info on using a non-root user as the ssh user, see Further information about cephadm bootstrap
Deployment with CA signed SSH keys
As an alternative to standard public key authentication, cephadm also supports
deployment using CA signed keys. Before bootstrapping it’s recommended to set up
the CA public key as a trusted CA key on hosts you’d like to eventually add to
the cluster. For example:
# we will act as our own CA, therefore we'll need to make a CA key
[root@host1 ~]# ssh-keygen -t rsa -f ca-key -N ""
# make the ca key trusted on the host we've generated it on
# this requires adding in a line in our /etc/sshd_config
# to mark this key as trusted
[root@host1 ~]# cp ca-key.pub /etc/ssh
[root@host1 ~]# vi /etc/ssh/sshd_config
[root@host1 ~]# cat /etc/ssh/sshd_config | grep ca-key
TrustedUserCAKeys /etc/ssh/ca-key.pub
# now restart sshd so it picks up the config change
[root@host1 ~]# systemctl restart sshd
# now, on all other hosts we want in the cluster, also install the CA key
[root@host1 ~]# scp /etc/ssh/ca-key.pub host2:/etc/ssh/
# on other hosts, make the same changes to the sshd_config
[root@host2 ~]# vi /etc/ssh/sshd_config
[root@host2 ~]# cat /etc/ssh/sshd_config | grep ca-key
TrustedUserCAKeys /etc/ssh/ca-key.pub
# and restart sshd so it picks up the config change
[root@host2 ~]# systemctl restart sshd
Once the CA key has been installed and marked as a trusted key, you are ready
to use a private key/CA signed cert combination for SSH. Continuing with our
current example, we will create a new key-pair for for host access and then
sign it with our CA key
# make a new key pair
[root@host1 ~]# ssh-keygen -t rsa -f cephadm-ssh-key -N ""
# sign the private key. This will create a new cephadm-ssh-key-cert.pub
# note here we're using user "root". If you'd like to use a non-root
# user the arguments to the -I and -n params would need to be adjusted
# Additionally, note the -V param indicates how long until the cert
# this creates will expire
[root@host1 ~]# ssh-keygen -s ca-key -I user_root -n root -V +52w cephadm-ssh-key
[root@host1 ~]# ls
ca-key ca-key.pub cephadm-ssh-key cephadm-ssh-key-cert.pub cephadm-ssh-key.pub
# verify our signed key is working. To do this, make sure the generated private
# key ("cephadm-ssh-key" in our example) and the newly signed cert are stored
# in the same directory. Then try to ssh using the private key
[root@host1 ~]# ssh -i cephadm-ssh-key host2
Once you have your private key and corresponding CA signed cert and have tested
SSH authentication using that key works, you can pass those keys to bootstrap
in order to have cephadm use them for SSHing between cluster hosts
[root@host1 ~]# cephadm bootstrap --mon-ip <ip-addr> --ssh-private-key cephadm-ssh-key --ssh-signed-cert cephadm-ssh-key-cert.pub
Note that this setup does not require installing the corresponding public key
from the private key passed to bootstrap on other nodes. In fact, cephadm will
reject the --ssh-public-key argument when passed along with --ssh-signed-cert.
Not because having the public key breaks anything, but because it is not at all needed
for this setup and it helps bootstrap differentiate if the user wants the CA signed
keys setup or standard pubkey encryption. What this means is, SSH key rotation
would simply be a matter of getting another key signed by the same CA and providing
cephadm with the new private key and signed cert. No additional distribution of
keys to cluster nodes is needed after the initial setup of the CA key as a trusted key,
no matter how many new private key/signed cert pairs are rotated in.
Revision 1d10b717.
