diff --git a/doc/sphinx/Pacemaker_Explained/resources.rst b/doc/sphinx/Pacemaker_Explained/resources.rst index 26449d3f85..54e9d99e17 100644 --- a/doc/sphinx/Pacemaker_Explained/resources.rst +++ b/doc/sphinx/Pacemaker_Explained/resources.rst @@ -1,800 +1,808 @@ .. _resource: Cluster Resources ----------------- .. _s-resource-primitive: What is a Cluster Resource? ########################### .. index:: single: resource A *resource* is a service managed by Pacemaker. The simplest type of resource, a *primitive*, is described in this chapter. More complex forms, such as groups and clones, are described in later chapters. Every primitive has a *resource agent* that provides Pacemaker a standardized interface for managing the service. This allows Pacemaker to be agnostic about the services it manages. Pacemaker doesn't need to understand how the service works because it relies on the resource agent to do the right thing when asked. Every resource has a *standard* (also called *class*) specifying the interface that its resource agent follows, and a *type* identifying the specific service being managed. .. _s-resource-supported: .. index:: single: resource; standard Resource Standards ################## Pacemaker can use resource agents complying with these standards, described in more detail below: * ocf * lsb * systemd * service * stonithd * nagios *(deprecated since 2.1.6)* * upstart *(deprecated since 2.1.0)* Support for some standards is controlled by build options and so might not be available in any particular build of Pacemaker. The command ``crm_resource --list-standards`` will show which standards are supported by the local build. .. index:: single: resource; OCF single: OCF; resources single: Open Cluster Framework; resources Open Cluster Framework ______________________ The Open Cluster Framework (OCF) Resource Agent API is a ClusterLabs standard for managing services. It is the most preferred since it is specifically designed for use in a Pacemaker cluster. OCF agents are scripts that support a variety of actions including ``start``, ``stop``, and ``monitor``. They may accept parameters, making them more flexible than other standards. The number and purpose of parameters is left to the agent, which advertises them via the ``meta-data`` action. Unlike other standards, OCF agents have a *provider* as well as a standard and type. For more information, see the "Resource Agents" chapter of *Pacemaker Administration* and the `OCF standard `_. .. _s-resource-supported-systemd: .. index:: single: Resource; Systemd single: Systemd; resources Systemd _______ Most Linux distributions use `Systemd `_ for system initialization and service management. *Unit files* specify how to manage services and are usually provided by the distribution. Pacemaker can manage systemd services. Simply create a resource with ``systemd`` as the resource standard and the unit file name as the resource type. Do *not* run ``systemctl enable`` on the unit. .. important:: Make sure that any systemd services to be controlled by the cluster are *not* enabled to start at boot. .. index:: single: resource; LSB single: LSB; resources single: Linux Standard Base; resources Linux Standard Base ___________________ *LSB* resource agents, also known as `SysV-style `_, are scripts that provide start, stop, and status actions for a service. They are provided by some operating system distributions. If a full path is not given, they are assumed to be located in a directory specified when your Pacemaker software was built (usually ``/etc/init.d``). In order to be used with Pacemaker, they must conform to the `LSB specification `_ as it relates to init scripts. .. warning:: Some LSB scripts do not fully comply with the standard. For details on how to check whether your script is LSB-compatible, see the "Resource Agents" chapter of `Pacemaker Administration`. Common problems include: * Not implementing the ``status`` action * Not observing the correct exit status codes * Starting a started resource returns an error * Stopping a stopped resource returns an error .. important:: Make sure the host is *not* configured to start any LSB services at boot that will be controlled by the cluster. .. index:: single: Resource; System Services single: System Service; resources System Services _______________ Since there are various types of system services (``systemd``, ``upstart``, and ``lsb``), Pacemaker supports a special ``service`` alias which intelligently figures out which one applies to a given cluster node. This is particularly useful when the cluster contains a mix of ``systemd``, ``upstart``, and ``lsb``. In order, Pacemaker will try to find the named service as: * an LSB init script * a Systemd unit file * an Upstart job .. index:: single: Resource; STONITH single: STONITH; resources STONITH _______ The ``stonith`` standard is used for managing fencing devices, discussed later in :ref:`fencing`. .. index:: single: Resource; Nagios Plugins single: Nagios Plugins; resources Nagios Plugins ______________ Nagios Plugins are a way to monitor services. Pacemaker can use these as resources, to react to a change in the service's status. To use plugins as resources, Pacemaker must have been built with support, and OCF-style meta-data for the plugins must be installed on nodes that can run them. Meta-data for several common plugins is provided by the `nagios-agents-metadata `_ project. The supported parameters for such a resource are same as the long options of the plugin. Start and monitor actions for plugin resources are implemented as invoking the plugin. A plugin result of "OK" (0) is treated as success, a result of "WARN" (1) is treated as a successful but degraded service, and any other result is considered a failure. A plugin resource is not going to change its status after recovery by restarting the plugin, so using them alone does not make sense with ``on-fail`` set (or left to default) to ``restart``. Another value could make sense, for example, if you want to fence or standby nodes that cannot reach some external service. A more common use case for plugin resources is to configure them with a ``container`` meta-attribute set to the name of another resource that actually makes the service available, such as a virtual machine or container. With ``container`` set, the plugin resource will automatically be colocated with the containing resource and ordered after it, and the containing resource will be considered failed if the plugin resource fails. This allows monitoring of a service inside a virtual machine or container, with recovery of the virtual machine or container if the service fails. .. warning:: Nagios support is deprecated in Pacemaker. Support will be dropped entirely at the next major release of Pacemaker. For monitoring a service inside a virtual machine or container, the recommended alternative is to configure the virtual machine as a guest node or the container as a :ref:`bundle `. For other use cases, or when the virtual machine or container image cannot be modified, the recommended alternative is to write a custom OCF agent for the service (which may even call the Nagios plugin as part of its status action). .. index:: single: Resource; Upstart single: Upstart; resources Upstart _______ Some Linux distributions previously used `Upstart `_ for system initialization and service management. Pacemaker is able to manage services using Upstart if the local system supports them and support was enabled when your Pacemaker software was built. The *jobs* that specify how services are managed are usually provided by the operating system distribution. .. important:: Make sure the host is *not* configured to start any Upstart services at boot that will be controlled by the cluster. .. warning:: Upstart support is deprecated in Pacemaker. Upstart is no longer actively maintained, and test platforms for it are no longer readily usable. Support will be dropped entirely at the next major release of Pacemaker. .. _primitive-resource: Resource Properties ################### These values tell the cluster which resource agent to use for the resource, where to find that resource agent and what standards it conforms to. .. table:: **Properties of a Primitive Resource** :widths: 1 4 +-------------+------------------------------------------------------------------+ | Field | Description | +=============+==================================================================+ | id | .. index:: | | | single: id; resource | | | single: resource; property, id | | | | | | Your name for the resource | +-------------+------------------------------------------------------------------+ | class | .. index:: | | | single: class; resource | | | single: resource; property, class | | | | | | The standard the resource agent conforms to. Allowed values: | | | ``lsb``, ``ocf``, ``service``, ``stonith``, ``systemd``, | | | ``nagios`` *(deprecated since 2.1.6)*, and ``upstart`` | | | *(deprecated since 2.1.0)* | +-------------+------------------------------------------------------------------+ | description | .. index:: | | | single: description; resource | | | single: resource; property, description | | | | | | A description of the Resource Agent, intended for local use. | | | E.g. ``IP address for website`` | +-------------+------------------------------------------------------------------+ | type | .. index:: | | | single: type; resource | | | single: resource; property, type | | | | | | The name of the Resource Agent you wish to use. E.g. | | | ``IPaddr`` or ``Filesystem`` | +-------------+------------------------------------------------------------------+ | provider | .. index:: | | | single: provider; resource | | | single: resource; property, provider | | | | | | The OCF spec allows multiple vendors to supply the same resource | | | agent. To use the OCF resource agents supplied by the Heartbeat | | | project, you would specify ``heartbeat`` here. | +-------------+------------------------------------------------------------------+ The XML definition of a resource can be queried with the **crm_resource** tool. For example: .. code-block:: none # crm_resource --resource Email --query-xml might produce: .. topic:: A system resource definition .. code-block:: xml .. note:: One of the main drawbacks to system services (LSB, systemd or Upstart) resources is that they do not allow any parameters! .. topic:: An OCF resource definition .. code-block:: xml .. _resource_options: Resource Options ################ Resources have two types of options: *meta-attributes* and *instance attributes*. Meta-attributes apply to any type of resource, while instance attributes are specific to each resource agent. Resource Meta-Attributes ________________________ Meta-attributes are used by the cluster to decide how a resource should behave and can be easily set using the ``--meta`` option of the **crm_resource** command. .. list-table:: **Meta-attributes of a Primitive Resource** :class: longtable :widths: 2 2 3 5 :header-rows: 1 * - Name - Type - Default - Description * - .. _meta_priority: .. index:: single: priority; resource option single: resource; option, priority priority - :ref:`score ` - 0 - If not all resources can be active, the cluster will stop lower-priority resources in order to keep higher-priority ones active. * - .. _meta_critical: .. index:: single: critical; resource option single: resource; option, critical critical - :ref:`boolean ` - true - Use this value as the default for ``influence`` in all :ref:`colocation constraints ` involving this resource, as well as in the implicit colocation constraints created if this resource is in a :ref:`group `. For details, see :ref:`s-coloc-influence`. *(since 2.1.0)* * - .. _meta_target_role: .. index:: single: target-role; resource option single: resource; option, target-role target-role - :ref:`enumeration ` - Started - What state should the cluster attempt to keep this resource in? Allowed values: * ``Stopped:`` Force the resource to be stopped * ``Started:`` Allow the resource to be started (and in the case of :ref:`promotable ` clone resources, promoted if appropriate) * ``Unpromoted:`` Allow the resource to be started, but only in the unpromoted role if the resource is :ref:`promotable ` * ``Promoted:`` Equivalent to ``Started`` * - .. _meta_is_managed: .. _is_managed: .. index:: single: is-managed; resource option single: resource; option, is-managed is-managed - :ref:`boolean ` - true - If false, the cluster will not start, stop, promote, or demote the resource on any node. Recurring actions for the resource are unaffected. Maintenance mode overrides this setting. * - .. _meta_maintenance: .. _rsc_maintenance: .. index:: single: maintenance; resource option single: resource; option, maintenance maintenance - :ref:`boolean ` - false - If true, the cluster will not start, stop, promote, or demote the resource on any node, and will pause any recurring monitors (except those specifying ``role`` as ``Stopped``). If true, the :ref:`maintenance-mode ` cluster option or :ref:`maintenance ` node attribute overrides this. * - .. _meta_resource_stickiness: .. _resource-stickiness: .. index:: single: resource-stickiness; resource option single: resource; option, resource-stickiness resource-stickiness - :ref:`score ` - 1 for individual clone instances, 0 for all other resources - A score that will be added to the current node when a resource is already active. This allows running resources to stay where they are, even if they would be placed elsewhere if they were being started from a stopped state. * - .. _meta_requires: .. _requires: .. index:: single: requires; resource option single: resource; option, requires requires - :ref:`enumeration ` - ``quorum`` for resources with a ``class`` of ``stonith``, otherwise ``unfencing`` if unfencing is active in the cluster, otherwise ``fencing`` if ``stonith-enabled`` is true, otherwise ``quorum`` - Conditions under which the resource can be started. Allowed values: * ``nothing:`` The cluster can always start this resource. * ``quorum:`` The cluster can start this resource only if a majority of the configured nodes are active. * ``fencing:`` The cluster can start this resource only if a majority of the configured nodes are active *and* any failed or unknown nodes have been :ref:`fenced `. * ``unfencing:`` The cluster can only start this resource if a majority of the configured nodes are active *and* any failed or unknown nodes have been fenced *and* only on nodes that have been :ref:`unfenced `. * - .. _meta_migration_threshold: .. index:: single: migration-threshold; resource option single: resource; option, migration-threshold migration-threshold - :ref:`score ` - INFINITY - How many failures may occur for this resource on a node, before this node is marked ineligible to host this resource. A value of 0 indicates that this feature is disabled (the node will never be marked ineligible); by contrast, the cluster treats ``INFINITY`` (the default) as a very large but finite number. This option has an effect only if the failed operation specifies ``on-fail`` as ``restart`` (the default), and additionally for failed ``start`` operations, if the cluster property ``start-failure-is-fatal`` is ``false``. * - .. _meta_failure_timeout: .. index:: single: failure-timeout; resource option single: resource; option, failure-timeout failure-timeout - :ref:`duration ` - 0 - - How many seconds to wait before acting as if the failure had not - occurred, and potentially allowing the resource back to the node on which - it failed. A value of 0 indicates that this feature is disabled. + - Ignore previously failed resource actions after this much time has + passed without new failures (potentially allowing the resource back to + the node on which it failed, if it previously reached its + ``migration-threshold`` there). A value of 0 indicates that failures do + not expire. **WARNING:** If this value is low, and pending cluster + activity prevents the cluster from responding to a failure within that + time, then the failure will be ignored completely and will not cause + recovery of the resource, even if a recurring action continues to report + failure. It should be at least greater than the longest :ref:`action + timeout ` for all resources in the cluster. A value in hours + or days is reasonable. * - .. _meta_multiple_active: .. index:: single: multiple-active; resource option single: resource; option, multiple-active multiple-active - :ref:`enumeration ` - stop_start - What should the cluster do if it ever finds the resource active on more than one node? Allowed values: * ``block``: mark the resource as unmanaged * ``stop_only``: stop all active instances and leave them that way * ``stop_start``: stop all active instances and start the resource in one location only * ``stop_unexpected``: stop all active instances except where the resource should be active (this should be used only when extra instances are not expected to disrupt existing instances, and the resource agent's monitor of an existing instance is capable of detecting any problems that could be caused; note that any resources ordered after this will still need to be restarted) *(since 2.1.3)* * - .. _meta_allow_migrate: .. index:: single: allow-migrate; resource option single: resource; option, allow-migrate allow-migrate - :ref:`boolean ` - true for ``ocf:pacemaker:remote`` resources, false otherwise - Whether the cluster should try to "live migrate" this resource when it needs to be moved (see :ref:`live-migration`) * - .. _meta_allow_unhealthy_nodes: .. index:: single: allow-unhealthy-nodes; resource option single: resource; option, allow-unhealthy-nodes allow-unhealthy-nodes - :ref:`boolean ` - false - Whether the resource should be able to run on a node even if the node's health score would otherwise prevent it (see :ref:`node-health`) *(since 2.1.3)* * - .. _meta_container_attribute_target: .. index:: single: container-attribute-target; resource option single: resource; option, container-attribute-target container-attribute-target - :ref:`enumeration ` - - Specific to bundle resources; see :ref:`s-bundle-attributes` * - .. _meta_remote_node: .. index:: single: remote-node; resource option single: resource; option, remote-node remote-node - :ref:`text ` - - The name of the Pacemaker Remote guest node this resource is associated with, if any. If specified, this both enables the resource as a guest node and defines the unique name used to identify the guest node. The guest must be configured to run the Pacemaker Remote daemon when it is started. **WARNING:** This value cannot overlap with any resource or node IDs. * - .. _meta_remote_addr: .. index:: single: remote-addr; resource option single: resource; option, remote-addr remote-addr - :ref:`text ` - value of ``remote-node`` - If ``remote-node`` is specified, the IP address or hostname used to connect to the guest via Pacemaker Remote. The Pacemaker Remote daemon on the guest must be configured to accept connections on this address. * - .. _meta_remote_port: .. index:: single: remote-port; resource option single: resource; option, remote-port remote-port - :ref:`port ` - 3121 - If ``remote-node`` is specified, the port on the guest used for its Pacemaker Remote connection. The Pacemaker Remote daemon on the guest must be configured to listen on this port. * - .. _meta_remote_connect_timeout: .. index:: single: remote-connect-timeout; resource option single: resource; option, remote-connect-timeout remote-connect-timeout - :ref:`timeout ` - 60s - If ``remote-node`` is specified, how long before a pending guest connection will time out. * - .. _meta_remote_allow_migrate: .. index:: single: remote-allow-migrate; resource option single: resource; option, remote-allow-migrate remote-allow-migrate - :ref:`boolean ` - true - If ``remote-node`` is specified, this acts as the ``allow-migrate`` meta-attribute for the implicit remote connection resource (``ocf:pacemaker:remote``). As an example of setting resource options, if you performed the following commands on an LSB Email resource: .. code-block:: none # crm_resource --meta --resource Email --set-parameter priority --parameter-value 100 # crm_resource -m -r Email -p multiple-active -v block the resulting resource definition might be: .. topic:: An LSB resource with cluster options .. code-block:: xml In addition to the cluster-defined meta-attributes described above, you may also configure arbitrary meta-attributes of your own choosing. Most commonly, this would be done for use in :ref:`rules `. For example, an IT department might define a custom meta-attribute to indicate which company department each resource is intended for. To reduce the chance of name collisions with cluster-defined meta-attributes added in the future, it is recommended to use a unique, organization-specific prefix for such attributes. .. _s-resource-defaults: Setting Global Defaults for Resource Meta-Attributes ____________________________________________________ To set a default value for a resource option, add it to the ``rsc_defaults`` section with ``crm_attribute``. For example, .. code-block:: none # crm_attribute --type rsc_defaults --name is-managed --update false would prevent the cluster from starting or stopping any of the resources in the configuration (unless of course the individual resources were specifically enabled by having their ``is-managed`` set to ``true``). Resource Instance Attributes ____________________________ The resource agents of some resource standards (lsb, systemd and upstart *not* among them) can be given parameters which determine how they behave and which instance of a service they control. If your resource agent supports parameters, you can add them with the ``crm_resource`` command. For example, .. code-block:: none # crm_resource --resource Public-IP --set-parameter ip --parameter-value 192.0.2.2 would create an entry in the resource like this: .. topic:: An example OCF resource with instance attributes .. code-block:: xml For an OCF resource, the result would be an environment variable called ``OCF_RESKEY_ip`` with a value of ``192.0.2.2``. The list of instance attributes supported by an OCF resource agent can be found by calling the resource agent with the ``meta-data`` command. The output contains an XML description of all the supported attributes, their purpose and default values. .. topic:: Displaying the metadata for the Dummy resource agent template .. code-block:: none # export OCF_ROOT=/usr/lib/ocf # $OCF_ROOT/resource.d/pacemaker/Dummy meta-data .. code-block:: xml 1.1 This is a dummy OCF resource agent. It does absolutely nothing except keep track of whether it is running or not, and can be configured so that actions fail or take a long time. Its purpose is primarily for testing, and to serve as a template for resource agent writers. Example stateless resource agent Location to store the resource state in. State file Fake password field Password Fake attribute that can be changed to cause a reload Fake attribute that can be changed to cause a reload Number of seconds to sleep during operations. This can be used to test how the cluster reacts to operation timeouts. Operation sleep duration in seconds. Start, migrate_from, and reload-agent actions will return failure if running on the host specified here, but the resource will run successfully anyway (future monitor calls will find it running). This can be used to test on-fail=ignore. Report bogus start failure on specified host If this is set, the environment will be dumped to this file for every call. Environment dump file