ceph/doc/cephadm/monitoring.rst
zdover23 3b787771ec
Merge pull request #41305 from zdover23/wip-doc-cephadm-monitoring-disabling-monitoring-2021-05-12
doc/cephadm: rewrite "disabling monitoring"

Reviewed-by: Josh Durgin <jdurgin@redhat.com>
2021-05-14 00:23:57 +10:00

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.. _mgr-cephadm-monitoring:
Monitoring Services
===================
Ceph Dashboard uses `Prometheus <https://prometheus.io/>`_, `Grafana
<https://grafana.com/>`_, and related tools to store and visualize detailed
metrics on cluster utilization and performance. Ceph users have three options:
#. Have cephadm deploy and configure these services. This is the default
when bootstrapping a new cluster unless the ``--skip-monitoring-stack``
option is used.
#. Deploy and configure these services manually. This is recommended for users
with existing prometheus services in their environment (and in cases where
Ceph is running in Kubernetes with Rook).
#. Skip the monitoring stack completely. Some Ceph dashboard graphs will
not be available.
The monitoring stack consists of `Prometheus <https://prometheus.io/>`_,
Prometheus exporters (:ref:`mgr-prometheus`, `Node exporter
<https://prometheus.io/docs/guides/node-exporter/>`_), `Prometheus Alert
Manager <https://prometheus.io/docs/alerting/alertmanager/>`_ and `Grafana
<https://grafana.com/>`_.
.. note::
Prometheus' security model presumes that untrusted users have access to the
Prometheus HTTP endpoint and logs. Untrusted users have access to all the
(meta)data Prometheus collects that is contained in the database, plus a
variety of operational and debugging information.
However, Prometheus' HTTP API is limited to read-only operations.
Configurations can *not* be changed using the API and secrets are not
exposed. Moreover, Prometheus has some built-in measures to mitigate the
impact of denial of service attacks.
Please see `Prometheus' Security model
<https://prometheus.io/docs/operating/security/>` for more detailed
information.
Deploying monitoring with cephadm
---------------------------------
By default, bootstrap will deploy a basic monitoring stack. If you
did not do this (by passing ``--skip-monitoring-stack``, or if you
converted an existing cluster to cephadm management, you can set up
monitoring by following the steps below.
#. Enable the prometheus module in the ceph-mgr daemon. This exposes the internal Ceph metrics so that prometheus can scrape them.
.. code-block:: bash
ceph mgr module enable prometheus
#. Deploy a node-exporter service on every node of the cluster. The node-exporter provides host-level metrics like CPU and memory utilization.
.. code-block:: bash
ceph orch apply node-exporter '*'
#. Deploy alertmanager
.. code-block:: bash
ceph orch apply alertmanager 1
#. Deploy prometheus. A single prometheus instance is sufficient, but
for HA you may want to deploy two.
.. code-block:: bash
ceph orch apply prometheus 1 # or 2
#. Deploy grafana
.. code-block:: bash
ceph orch apply grafana 1
Cephadm takes care of the configuration of Prometheus, Grafana, and Alertmanager
automatically.
However, there is one exception to this rule. In a some setups, the Dashboard
user's browser might not be able to access the Grafana URL configured in Ceph
Dashboard. One such scenario is when the cluster and the accessing user are each
in a different DNS zone.
For this case, there is an extra configuration option for Ceph Dashboard, which
can be used to configure the URL for accessing Grafana by the user's browser.
This value will never be altered by cephadm. To set this configuration option,
issue the following command::
$ ceph dashboard set-grafana-frontend-api-url <grafana-server-api>
It may take a minute or two for services to be deployed. Once
completed, you should see something like this from ``ceph orch ls``
.. code-block:: console
$ ceph orch ls
NAME RUNNING REFRESHED IMAGE NAME IMAGE ID SPEC
alertmanager 1/1 6s ago docker.io/prom/alertmanager:latest 0881eb8f169f present
crash 2/2 6s ago docker.io/ceph/daemon-base:latest-master-devel mix present
grafana 1/1 0s ago docker.io/pcuzner/ceph-grafana-el8:latest f77afcf0bcf6 absent
node-exporter 2/2 6s ago docker.io/prom/node-exporter:latest e5a616e4b9cf present
prometheus 1/1 6s ago docker.io/prom/prometheus:latest e935122ab143 present
Configuring SSL/TLS for Grafana
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
``cephadm`` deploys Grafana using the certificate defined in the ceph
key/value store. If no certificate is specified, ``cephadm`` generates a
self-signed certificate during the deployment of the Grafana service.
A custom certificate can be configured using the following commands:
.. prompt:: bash #
ceph config-key set mgr/cephadm/grafana_key -i $PWD/key.pem
ceph config-key set mgr/cephadm/grafana_crt -i $PWD/certificate.pem
If you have already deployed Grafana, run ``reconfig`` on the service to
update its configuration:
.. prompt:: bash #
ceph orch reconfig grafana
The ``reconfig`` command also sets the proper URL for Ceph Dashboard.
Using custom images
~~~~~~~~~~~~~~~~~~~
It is possible to install or upgrade monitoring components based on other
images. To do so, the name of the image to be used needs to be stored in the
configuration first. The following configuration options are available.
- ``container_image_prometheus``
- ``container_image_grafana``
- ``container_image_alertmanager``
- ``container_image_node_exporter``
Custom images can be set with the ``ceph config`` command
.. code-block:: bash
ceph config set mgr mgr/cephadm/<option_name> <value>
For example
.. code-block:: bash
ceph config set mgr mgr/cephadm/container_image_prometheus prom/prometheus:v1.4.1
.. note::
By setting a custom image, the default value will be overridden (but not
overwritten). The default value changes when updates become available.
By setting a custom image, you will not be able to update the component
you have set the custom image for automatically. You will need to
manually update the configuration (image name and tag) to be able to
install updates.
If you choose to go with the recommendations instead, you can reset the
custom image you have set before. After that, the default value will be
used again. Use ``ceph config rm`` to reset the configuration option
.. code-block:: bash
ceph config rm mgr mgr/cephadm/<option_name>
For example
.. code-block:: bash
ceph config rm mgr mgr/cephadm/container_image_prometheus
Using custom configuration files
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By overriding cephadm templates, it is possible to completely customize the
configuration files for monitoring services.
Internally, cephadm already uses `Jinja2
<https://jinja.palletsprojects.com/en/2.11.x/>`_ templates to generate the
configuration files for all monitoring components. To be able to customize the
configuration of Prometheus, Grafana or the Alertmanager it is possible to store
a Jinja2 template for each service that will be used for configuration
generation instead. This template will be evaluated every time a service of that
kind is deployed or reconfigured. That way, the custom configuration is
preserved and automatically applied on future deployments of these services.
.. note::
The configuration of the custom template is also preserved when the default
configuration of cephadm changes. If the updated configuration is to be used,
the custom template needs to be migrated *manually*.
Option names
""""""""""""
The following templates for files that will be generated by cephadm can be
overridden. These are the names to be used when storing with ``ceph config-key
set``:
- ``services/alertmanager/alertmanager.yml``
- ``services/grafana/ceph-dashboard.yml``
- ``services/grafana/grafana.ini``
- ``services/prometheus/prometheus.yml``
You can look up the file templates that are currently used by cephadm in
``src/pybind/mgr/cephadm/templates``:
- ``services/alertmanager/alertmanager.yml.j2``
- ``services/grafana/ceph-dashboard.yml.j2``
- ``services/grafana/grafana.ini.j2``
- ``services/prometheus/prometheus.yml.j2``
Usage
"""""
The following command applies a single line value:
.. code-block:: bash
ceph config-key set mgr/cephadm/<option_name> <value>
To set contents of files as template use the ``-i`` argument:
.. code-block:: bash
ceph config-key set mgr/cephadm/<option_name> -i $PWD/<filename>
.. note::
When using files as input to ``config-key`` an absolute path to the file must
be used.
Then the configuration file for the service needs to be recreated.
This is done using `reconfig`. For more details see the following example.
Example
"""""""
.. code-block:: bash
# set the contents of ./prometheus.yml.j2 as template
ceph config-key set mgr/cephadm/services/prometheus/prometheus.yml \
-i $PWD/prometheus.yml.j2
# reconfig the prometheus service
ceph orch reconfig prometheus
Disabling monitoring
--------------------
To disable monitoring and remove the software that supports it, run the following commands:
.. code-block:: console
$ ceph orch rm grafana
$ ceph orch rm prometheus --force # this will delete metrics data collected so far
$ ceph orch rm node-exporter
$ ceph orch rm alertmanager
$ ceph mgr module disable prometheus
Deploying monitoring manually
-----------------------------
If you have an existing prometheus monitoring infrastructure, or would like
to manage it yourself, you need to configure it to integrate with your Ceph
cluster.
* Enable the prometheus module in the ceph-mgr daemon
.. code-block:: bash
ceph mgr module enable prometheus
By default, ceph-mgr presents prometheus metrics on port 9283 on each host
running a ceph-mgr daemon. Configure prometheus to scrape these.
* To enable the dashboard's prometheus-based alerting, see :ref:`dashboard-alerting`.
* To enable dashboard integration with Grafana, see :ref:`dashboard-grafana`.
Enabling RBD-Image monitoring
---------------------------------
Due to performance reasons, monitoring of RBD images is disabled by default. For more information please see
:ref:`prometheus-rbd-io-statistics`. If disabled, the overview and details dashboards will stay empty in Grafana
and the metrics will not be visible in Prometheus.