diff --git a/doc/sphinx/Pacemaker_Explained/collective.rst b/doc/sphinx/Pacemaker_Explained/collective.rst index 36142a7132..76f6a7845a 100644 --- a/doc/sphinx/Pacemaker_Explained/collective.rst +++ b/doc/sphinx/Pacemaker_Explained/collective.rst @@ -1,1203 +1,1204 @@ .. index: single: collective resource single: resource; collective Collective Resources -------------------- Pacemaker supports several types of *collective* resources, which consist of multiple, related resource instances. .. index: single: group resource single: resource; group .. _group-resources: Groups - A Syntactic Shortcut ############################# One of the most common elements of a cluster is a set of resources that need to be located together, start sequentially, and stop in the reverse order. To simplify this configuration, we support the concept of groups. .. topic:: A group of two primitive resources .. code-block:: xml Although the example above contains only two resources, there is no limit to the number of resources a group can contain. The example is also sufficient to explain the fundamental properties of a group: * Resources are started in the order they appear in (**Public-IP** first, then **Email**) * Resources are stopped in the reverse order to which they appear in (**Email** first, then **Public-IP**) If a resource in the group can't run anywhere, then nothing after that is allowed to run, too. * If **Public-IP** can't run anywhere, neither can **Email**; * but if **Email** can't run anywhere, this does not affect **Public-IP** in any way The group above is logically equivalent to writing: .. topic:: How the cluster sees a group resource .. code-block:: xml Obviously as the group grows bigger, the reduced configuration effort can become significant. Another (typical) example of a group is a DRBD volume, the filesystem mount, an IP address, and an application that uses them. .. index:: pair: XML element; group Group Properties ________________ .. list-table:: **Properties of a Group Resource** :widths: 25 75 :header-rows: 1 * - Field - Description * - id - .. index:: single: group; property, id single: property; id (group) single: id; group property A unique name for the group * - description - .. index:: single: group; attribute, description single: attribute; description (group) single: description; group attribute Arbitrary text for user's use (ignored by Pacemaker) Group Options _____________ Groups inherit the ``priority``, ``target-role``, and ``is-managed`` properties from primitive resources. See :ref:`resource_options` for information about those properties. Group Instance Attributes _________________________ Groups have no instance attributes. However, any that are set for the group object will be inherited by the group's children. Group Contents ______________ Groups may only contain a collection of cluster resources (see :ref:`primitive-resource`). To refer to a child of a group resource, just use the child's ``id`` instead of the group's. Group Constraints _________________ Although it is possible to reference a group's children in constraints, it is usually preferable to reference the group itself. .. topic:: Some constraints involving groups .. code-block:: xml .. index:: pair: resource-stickiness; group Group Stickiness ________________ Stickiness, the measure of how much a resource wants to stay where it is, is additive in groups. Every active resource of the group will contribute its stickiness value to the group's total. So if the default ``resource-stickiness`` is 100, and a group has seven members, five of which are active, then the group as a whole will prefer its current location with a score of 500. .. index:: single: clone single: resource; clone .. _s-resource-clone: Clones - Resources That Can Have Multiple Active Instances ########################################################## *Clone* resources are resources that can have more than one copy active at the same time. This allows you, for example, to run a copy of a daemon on every node. You can clone any primitive or group resource [#]_. Anonymous versus Unique Clones ______________________________ A clone resource is configured to be either *anonymous* or *globally unique*. Anonymous clones are the simplest. These behave completely identically everywhere they are running. Because of this, there can be only one instance of an anonymous clone active per node. The instances of globally unique clones are distinct entities. All instances are launched identically, but one instance of the clone is not identical to any other instance, whether running on the same node or a different node. As an example, a cloned IP address can use special kernel functionality such that each instance handles a subset of requests for the same IP address. .. index:: single: promotable clone single: resource; promotable .. _s-resource-promotable: Promotable clones _________________ If a clone is *promotable*, its instances can perform a special role that Pacemaker will manage via the ``promote`` and ``demote`` actions of the resource agent. Services that support such a special role have various terms for the special role and the default role: primary and secondary, master and replica, controller and worker, etc. Pacemaker uses the terms *promoted* and *unpromoted* to be agnostic to what the service calls them or what they do. All that Pacemaker cares about is that an instance comes up in the unpromoted role when started, and the resource agent supports the ``promote`` and ``demote`` actions to manage entering and exiting the promoted role. .. index:: pair: XML element; clone Clone Properties ________________ .. list-table:: **Properties of a Clone Resource** :widths: 25 75 :header-rows: 1 * - Field - Description * - id - .. index:: single: clone; property, id single: property; id (clone) single: id; clone property A unique name for the clone * - description - .. index:: single: clone; attribute, description single: attribute; description (clone) single: description; clone attribute Arbitrary text for user's use (ignored by Pacemaker) .. index:: pair: options; clone Clone Options _____________ :ref:`Options ` inherited from primitive resources: ``priority, target-role, is-managed`` .. list-table:: **Clone-Specific Configuration Options** :class: longtable :widths: 20 20 60 :header-rows: 1 * - Field - Default - Description * - globally-unique - **true** if clone-node-max is greater than 1 *(since 3.0.0)*, otherwise **false** - .. index:: single: clone; option, globally-unique single: option; globally-unique (clone) single: globally-unique; clone option If **true**, each clone instance performs a distinct function, such that a single node can run more than one instance at the same time * - clone-max - 0 - .. index:: single: clone; option, clone-max single: option; clone-max (clone) single: clone-max; clone option The maximum number of clone instances that can be started across the entire cluster. If 0, the number of nodes in the cluster will be used. * - clone-node-max - 1 - .. index:: single: clone; option, clone-node-max single: option; clone-node-max (clone) single: clone-node-max; clone option If the clone is globally unique, this is the maximum number of clone instances that can be started on a single node * - clone-min - 0 - .. index:: single: clone; option, clone-min single: option; clone-min (clone) single: clone-min; clone option Require at least this number of clone instances to be runnable before allowing resources depending on the clone to be runnable. A value of 0 means require all clone instances to be runnable. * - notify - false - .. index:: single: clone; option, notify single: option; notify (clone) single: notify; clone option Call the resource agent's **notify** action for all active instances, before and after starting or stopping any clone instance. The resource agent must support this action. Allowed values: **false**, **true** * - ordered - false - .. index:: single: clone; option, ordered single: option; ordered (clone) single: ordered; clone option If **true**, clone instances must be started sequentially instead of in parallel. Allowed values: **false**, **true** * - interleave - false - .. index:: single: clone; option, interleave single: option; interleave (clone) single: interleave; clone option When this clone is ordered relative to another clone, if this option is **false** (the default), the ordering is relative to *all* instances of the other clone, whereas if this option is **true**, the ordering is relative only to instances on the same node. Allowed values: **false**, **true** * - promotable - false - .. index:: single: clone; option, promotable single: option; promotable (clone) single: promotable; clone option If **true**, clone instances can perform a special role that Pacemaker will manage via the resource agent's **promote** and **demote** actions. The resource agent must support these actions. Allowed values: **false**, **true** * - promoted-max - 1 - .. index:: single: clone; option, promoted-max single: option; promoted-max (clone) single: promoted-max; clone option If ``promotable`` is **true**, the number of instances that can be promoted at one time across the entire cluster * - promoted-node-max - 1 - .. index:: single: clone; option, promoted-node-max single: option; promoted-node-max (clone) single: promoted-node-max; clone option If the clone is promotable and globally unique, this is the number of instances that can be promoted at one time on a single node (up to ``clone-node-max``) .. note:: **Deprecated Terminology** In older documentation and online examples, you may see promotable clones referred to as *multi-state*, *stateful*, or *master/slave*; these mean the same thing as *promotable*. Certain syntax is supported for backward compatibility, but is deprecated and will be removed in a future version: * Using the ``master-max`` meta-attribute instead of ``promoted-max`` * Using the ``master-node-max`` meta-attribute instead of ``promoted-node-max`` * Using ``Master`` as a role name instead of ``Promoted`` * Using ``Slave`` as a role name instead of ``Unpromoted`` Clone Contents ______________ Clones must contain exactly one primitive or group resource. .. topic:: A clone that runs a web server on all nodes .. code-block:: xml .. warning:: You should never reference the name of a clone's child (the primitive or group resource being cloned). If you think you need to do this, you probably need to re-evaluate your design. Clone Instance Attribute ________________________ Clones have no instance attributes; however, any that are set here will be inherited by the clone's child. .. index:: single: clone; constraint Clone Constraints _________________ In most cases, a clone will have a single instance on each active cluster node. If this is not the case, you can indicate which nodes the cluster should preferentially assign copies to with resource location constraints. These constraints are written no differently from those for primitive resources except that the clone's **id** is used. .. topic:: Some constraints involving clones .. code-block:: xml Ordering constraints behave slightly differently for clones. In the example above, ``apache-stats`` will wait until all copies of ``apache-clone`` that need to be started have done so before being started itself. Only if *no* copies can be started will ``apache-stats`` be prevented from being active. Additionally, the clone will wait for ``apache-stats`` to be stopped before stopping itself. Colocation of a primitive or group resource with a clone means that the resource can run on any node with an active instance of the clone. The cluster will choose an instance based on where the clone is running and the resource's own location preferences. Colocation between clones is also possible. If one clone **A** is colocated with another clone **B**, the set of allowed locations for **A** is limited to nodes on which **B** is (or will be) active. Placement is then performed normally. .. index:: single: promotable clone; constraint .. _promotable-clone-constraints: Promotable Clone Constraints ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For promotable clone resources, the ``first-action`` and/or ``then-action`` fields for ordering constraints may be set to ``promote`` or ``demote`` to constrain the promoted role, and colocation constraints may contain ``rsc-role`` and/or ``with-rsc-role`` fields. .. topic:: Constraints involving promotable clone resources .. code-block:: xml In the example above, **myApp** will wait until one of the database copies has been started and promoted before being started itself on the same node. Only if no copies can be promoted will **myApp** be prevented from being active. Additionally, the cluster will wait for **myApp** to be stopped before demoting the database. Colocation of a primitive or group resource with a promotable clone resource means that it can run on any node with an active instance of the promotable clone resource that has the specified role (``Promoted`` or ``Unpromoted``). In the example above, the cluster will choose a location based on where database is running in the promoted role, and if there are multiple promoted instances it will also factor in **myApp**'s own location preferences when deciding which location to choose. Colocation with regular clones and other promotable clone resources is also possible. In such cases, the set of allowed locations for the **rsc** clone is (after role filtering) limited to nodes on which the ``with-rsc`` promotable clone resource is (or will be) in the specified role. Placement is then performed as normal. Using Promotable Clone Resources in Colocation Sets ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When a promotable clone is used in a :ref:`resource set ` inside a colocation constraint, the resource set may take a ``role`` attribute. In the following example, an instance of **B** may be promoted only on a node where **A** is in the promoted role. Additionally, resources **C** and **D** must be located on a node where both **A** and **B** are promoted. .. topic:: Colocate C and D with A's and B's promoted instances .. code-block:: xml Using Promotable Clone Resources in Ordered Sets ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When a promotable clone is used in a :ref:`resource set ` inside an ordering constraint, the resource set may take an ``action`` attribute. .. topic:: Start C and D after first promoting A and B .. code-block:: xml In the above example, **B** cannot be promoted until **A** has been promoted. Additionally, resources **C** and **D** must wait until **A** and **B** have been promoted before they can start. .. index:: pair: resource-stickiness; clone .. _s-clone-stickiness: Clone Stickiness ________________ To achieve stable assignments, clones are slightly sticky by default. If no value for ``resource-stickiness`` is provided, the clone will use a value of 1. Being a small value, it causes minimal disturbance to the score calculations of other resources but is enough to prevent Pacemaker from needlessly moving instances around the cluster. .. note:: For globally unique clones, this may result in multiple instances of the clone staying on a single node, even after another eligible node becomes active (for example, after being put into standby mode then made active again). If you do not want this behavior, specify a ``resource-stickiness`` of 0 for the clone temporarily and let the cluster adjust, then set it back to 1 if you want the default behavior to apply again. .. important:: If ``resource-stickiness`` is set in the ``rsc_defaults`` section, it will apply to clone instances as well. This means an explicit ``resource-stickiness`` of 0 in ``rsc_defaults`` works differently from the implicit default used when ``resource-stickiness`` is not specified. Monitoring Promotable Clone Resources _____________________________________ The usual monitor actions are insufficient to monitor a promotable clone resource, because Pacemaker needs to verify not only that the resource is active, but also that its actual role matches its intended one. Define two monitoring actions: the usual one will cover the unpromoted role, and an additional one with ``role="Promoted"`` will cover the promoted role. .. topic:: Monitoring both states of a promotable clone resource .. code-block:: xml .. important:: It is crucial that *every* monitor operation has a different interval! Pacemaker currently differentiates between operations only by resource and interval; so if (for example) a promotable clone resource had the same monitor interval for both roles, Pacemaker would ignore the role when checking the status -- which would cause unexpected return codes, and therefore unnecessary complications. .. _s-promotion-scores: Determining Which Instance is Promoted ______________________________________ Pacemaker can choose a promotable clone instance to be promoted in one of two ways: * Promotion scores: These are node attributes set via the ``crm_attribute`` command using the ``--promotion`` option, which generally would be called by the resource agent's start action if it supports promotable clones. This tool automatically detects both the resource and host, and should be used to set a preference for being promoted. Based on this, ``promoted-max``, and ``promoted-node-max``, the instance(s) with the highest preference will be promoted. * Constraints: Location constraints can indicate which nodes are most preferred to be promoted. .. topic:: Explicitly preferring node1 to be promoted .. code-block:: xml .. index: single: bundle single: resource; bundle pair: container; Docker pair: container; podman .. _s-resource-bundle: Bundles - Containerized Resources ################################# Pacemaker supports a special syntax for launching a service inside a `container `_ with any infrastructure it requires: the *bundle*. Pacemaker bundles support `Docker `_ and `podman `_ *(since 2.0.1)* container technologies. [#]_ .. topic:: A bundle for a containerized web server .. code-block:: xml Bundle Prerequisites ____________________ Before configuring a bundle in Pacemaker, the user must install the appropriate container launch technology (Docker or podman), and supply a fully configured container image, on every node allowed to run the bundle. Pacemaker will create an implicit resource of type **ocf:heartbeat:docker** or **ocf:heartbeat:podman** to manage a bundle's container. The user must ensure that the appropriate resource agent is installed on every node allowed to run the bundle. .. index:: pair: XML element; bundle Bundle Properties _________________ .. list-table:: **XML Attributes of a bundle Element** :widths: 25 75 :header-rows: 1 * - Field - Description * - id - .. index:: single: bundle; attribute, id single: attribute; id (bundle) single: id; bundle attribute A unique name for the bundle (required) * - description - .. index:: single: bundle; attribute, description single: attribute; description (bundle) single: description; bundle attribute Arbitrary text for user's use (ignored by Pacemaker) A bundle must contain exactly one ``docker`` or ``podman`` element. .. index:: pair: XML element; docker pair: XML element; podman Bundle Container Properties ___________________________ .. list-table:: **XML Attributes of a docker or podman Element** :class: longtable :widths: 15 40 45 :header-rows: 1 * - Attribute - Default - Description * - image - - .. index:: single: docker; attribute, image single: attribute; image (docker) single: image; docker attribute single: podman; attribute, image single: attribute; image (podman) single: image; podman attribute Container image tag (required) * - replicas - Value of ``promoted-max`` if that is positive, else 1 - .. index:: single: docker; attribute, replicas single: attribute; replicas (docker) single: replicas; docker attribute single: podman; attribute, replicas single: attribute; replicas (podman) single: replicas; podman attribute A positive integer specifying the number of container instances to launch * - replicas-per-host - 1 - .. index:: single: docker; attribute, replicas-per-host single: attribute; replicas-per-host (docker) single: replicas-per-host; docker attribute single: podman; attribute, replicas-per-host single: attribute; replicas-per-host (podman) single: replicas-per-host; podman attribute A positive integer specifying the number of container instances allowed to run on a single node * - promoted-max - 0 - .. index:: single: docker; attribute, promoted-max single: attribute; promoted-max (docker) single: promoted-max; docker attribute single: podman; attribute, promoted-max single: attribute; promoted-max (podman) single: promoted-max; podman attribute A non-negative integer that, if positive, indicates that the containerized service should be treated as a promotable service, with this many replicas allowed to run the service in the promoted role * - network - - .. index:: single: docker; attribute, network single: attribute; network (docker) single: network; docker attribute single: podman; attribute, network single: attribute; network (podman) single: network; podman attribute If specified, this will be passed to the ``docker run`` or ``podman run`` command as the network setting for the container. * - run-command - ``/usr/sbin/pacemaker-remoted`` if bundle contains a **primitive**, otherwise none - .. index:: single: docker; attribute, run-command single: attribute; run-command (docker) single: run-command; docker attribute single: podman; attribute, run-command single: attribute; run-command (podman) single: run-command; podman attribute This command will be run inside the container when launching it ("PID 1"). If the bundle contains a **primitive**, this command *must* start ``pacemaker-remoted`` (but could, for example, be a script that does other stuff, too). * - options - - .. index:: single: docker; attribute, options single: attribute; options (docker) single: options; docker attribute single: podman; attribute, options single: attribute; options (podman) single: options; podman attribute Extra command-line options to pass to the ``docker run`` or ``podman run`` command .. note:: Considerations when using cluster configurations or container images from Pacemaker 1.1: * If the container image has a pre-2.0.0 version of Pacemaker, set ``run-command`` to ``/usr/sbin/pacemaker_remoted`` (note the underbar instead of dash). * ``masters`` is accepted as an alias for ``promoted-max``, but is deprecated since 2.0.0, and support for it will be removed in a future version. Bundle Network Properties _________________________ A bundle may optionally contain one ```` element. .. index:: pair: XML element; network single: bundle; network .. list-table:: **XML Attributes of a network Element** :class: longtable :widths: 20 20 60 :header-rows: 1 * - Attribute - Default - Description * - add-host - TRUE - .. index:: single: network; attribute, add-host single: attribute; add-host (network) single: add-host; network attribute If TRUE, and ``ip-range-start`` is used, Pacemaker will automatically ensure that ``/etc/hosts`` inside the containers has entries for each :ref:`replica name ` and its assigned IP. * - ip-range-start - - .. index:: single: network; attribute, ip-range-start single: attribute; ip-range-start (network) single: ip-range-start; network attribute If specified, Pacemaker will create an implicit ``ocf:heartbeat:IPaddr2`` resource for each container instance, starting with this IP address, using up to ``replicas`` sequential addresses. These addresses can be used from the host's network to reach the service inside the container, though it is not visible within the container itself. Only IPv4 addresses are currently supported. * - host-netmask - 32 - .. index:: single: network; attribute; host-netmask single: attribute; host-netmask (network) single: host-netmask; network attribute If ``ip-range-start`` is specified, the IP addresses are created with this CIDR netmask (as a number of bits). * - host-interface - - .. index:: single: network; attribute; host-interface single: attribute; host-interface (network) single: host-interface; network attribute If ``ip-range-start`` is specified, the IP addresses are created on this host interface (by default, it will be determined from the IP address). * - control-port - 3121 - .. index:: single: network; attribute; control-port single: attribute; control-port (network) single: control-port; network attribute If the bundle contains a ``primitive``, the cluster will use this integer TCP port for communication with Pacemaker Remote inside the container. Changing this is useful when the container is unable to listen on the default port, for example, when the container uses the host's network rather than ``ip-range-start`` (in which case ``replicas-per-host`` must be 1), or when the bundle may run on a Pacemaker Remote node that is already listening on the default port. Any ``PCMK_remote_port`` environment variable set on the host or in the container is ignored for bundle connections. .. _s-resource-bundle-note-replica-names: .. note:: Replicas are named by the bundle id plus a dash and an integer counter starting with zero. For example, if a bundle named **httpd-bundle** has **replicas=2**, its containers will be named **httpd-bundle-0** and **httpd-bundle-1**. .. index:: pair: XML element; port-mapping Additionally, a ``network`` element may optionally contain one or more ``port-mapping`` elements. .. list-table:: **Attributes of a port-mapping Element** :class: longtable :widths: 20 20 60 :header-rows: 1 * - Attribute - Default - Description * - id - - .. index:: single: port-mapping; attribute, id single: attribute; id (port-mapping) single: id; port-mapping attribute A unique name for the port mapping (required) * - port - - .. index:: single: port-mapping; attribute, port single: attribute; port (port-mapping) single: port; port-mapping attribute If this is specified, connections to this TCP port number on the host network (on the container's assigned IP address, if ``ip-range-start`` is specified) will be forwarded to the container network. Exactly one of ``port`` or ``range`` must be specified in a ``port-mapping``. * - internal-port - value of ``port`` - .. index:: single: port-mapping; attribute, internal-port single: attribute; internal-port (port-mapping) single: internal-port; port-mapping attribute If ``port`` and this are specified, connections to ``port`` on the host's network will be forwarded to this port on the container network. * - range - - .. index:: single: port-mapping; attribute, range single: attribute; range (port-mapping) single: range; port-mapping attribute If this is specified, connections to these TCP port numbers (expressed as *first_port*-*last_port*) on the host network (on the container's assigned IP address, if ``ip-range-start`` is specified) will be forwarded to the same ports in the container network. Exactly one of ``port`` or ``range`` must be specified in a ``port-mapping``. .. note:: If the bundle contains a ``primitive``, Pacemaker will automatically map the ``control-port``, so it is not necessary to specify that port in a ``port-mapping``. .. index: pair: XML element; storage pair: XML element; storage-mapping single: bundle; storage .. _s-bundle-storage: Bundle Storage Properties _________________________ A bundle may optionally contain one ``storage`` element. A ``storage`` element has no properties of its own, but may contain one or more ``storage-mapping`` elements. .. list-table:: **Attributes of a storage-mapping Element** :class: longtable :widths: 20 20 60 :header-rows: 1 * - Attribute - Default - Description * - id - - .. index:: single: storage-mapping; attribute, id single: attribute; id (storage-mapping) single: id; storage-mapping attribute A unique name for the storage mapping (required) * - source-dir - - .. index:: single: storage-mapping; attribute, source-dir single: attribute; source-dir (storage-mapping) single: source-dir; storage-mapping attribute The absolute path on the host's filesystem that will be mapped into the container. Exactly one of ``source-dir`` and ``source-dir-root`` must be specified in a ``storage-mapping``. * - source-dir-root - - .. index:: single: storage-mapping; attribute, source-dir-root single: attribute; source-dir-root (storage-mapping) single: source-dir-root; storage-mapping attribute The start of a path on the host's filesystem that will be mapped into the container, using a different subdirectory on the host for each container instance. The subdirectory will be named the same as the :ref:`replica name `. Exactly one of ``source-dir`` and ``source-dir-root`` must be specified in a ``storage-mapping``. * - target-dir - - .. index:: single: storage-mapping; attribute, target-dir single: attribute; target-dir (storage-mapping) single: target-dir; storage-mapping attribute The path name within the container where the host storage will be mapped (required) * - options - - .. index:: single: storage-mapping; attribute, options single: attribute; options (storage-mapping) single: options; storage-mapping attribute A comma-separated list of file system mount options to use when mapping the storage .. note:: Pacemaker does not define the behavior if the source directory does not already exist on the host. However, it is expected that the container technology and/or its resource agent will create the source directory in that case. .. note:: If the bundle contains a ``primitive``, Pacemaker will automatically map the equivalent of ``source-dir=/etc/pacemaker/authkey target-dir=/etc/pacemaker/authkey`` and ``source-dir-root=/var/log/pacemaker/bundles target-dir=/var/log`` into the container, so it is not necessary to specify those paths in a ``storage-mapping``. .. important:: The ``PCMK_authkey_location`` environment variable must not be set to anything other than the default of ``/etc/pacemaker/authkey`` on any node in the cluster. .. important:: If SELinux is used in enforcing mode on the host, you must ensure the container is allowed to use any storage you mount into it. For Docker and podman bundles, adding "Z" to the mount options will create a container-specific label for the mount that allows the container access. .. index:: single: bundle; primitive Bundle Primitive ________________ A bundle may optionally contain one :ref:`primitive ` resource. The primitive may have operations, instance attributes, and meta-attributes defined, as usual. If a bundle contains a primitive resource, the container image must include the Pacemaker Remote daemon, and at least one of ``ip-range-start`` or ``control-port`` must be configured in the bundle. Pacemaker will create an implicit **ocf:pacemaker:remote** resource for the connection, launch Pacemaker Remote within the container, and monitor and manage the primitive resource via Pacemaker Remote. If the bundle has more than one container instance (replica), the primitive resource will function as an implicit :ref:`clone ` -- a :ref:`promotable clone ` if the bundle has ``promoted-max`` greater than zero. .. note:: If you want to pass environment variables to a bundle's Pacemaker Remote connection or primitive, you have two options: * Environment variables whose value is the same regardless of the underlying host may be set using the container element's ``options`` attribute. * If you want variables to have host-specific values, you can use the - :ref:`storage-mapping ` element to map a file on the host as - ``/etc/pacemaker/pcmk-init.env`` in the container *(since 2.0.3)*. - Pacemaker Remote will parse this file as a shell-like format, with - variables set as NAME=VALUE, ignoring blank lines and comments starting - with "#". - + :ref:`storage-mapping ` element to map a file on the host + as |PCMK_INIT_ENV_FILE| in the container *(since 2.0.3)*. Pacemaker Remote + will parse this file in a manner similar to a POSIX shell, with variables + set as NAME=VALUE, ignoring blank lines and comments starting with ``#``. + An assignment may not span multiple lines, and multiple assignments per + line are not supported. + .. important:: When a bundle has a ``primitive``, Pacemaker on all cluster nodes must be able to contact Pacemaker Remote inside the bundle's containers. * The containers must have an accessible network (for example, ``network`` should not be set to "none" with a ``primitive``). * The default, using a distinct network space inside the container, works in combination with ``ip-range-start``. Any firewall must allow access from all cluster nodes to the ``control-port`` on the container IPs. * If the container shares the host's network space (for example, by setting ``network`` to "host"), a unique ``control-port`` should be specified for each bundle. Any firewall must allow access from all cluster nodes to the ``control-port`` on all cluster and remote node IPs. .. index:: single: bundle; node attributes .. _s-bundle-attributes: Bundle Node Attributes ______________________ If the bundle has a ``primitive``, the primitive's resource agent may want to set node attributes such as :ref:`promotion scores `. However, with containers, it is not apparent which node should get the attribute. If the container uses shared storage that is the same no matter which node the container is hosted on, then it is appropriate to use the promotion score on the bundle node itself. On the other hand, if the container uses storage exported from the underlying host, then it may be more appropriate to use the promotion score on the underlying host. Since this depends on the particular situation, the ``container-attribute-target`` resource meta-attribute allows the user to specify which approach to use. If it is set to ``host``, then user-defined node attributes will be checked on the underlying host. If it is anything else, the local node (in this case the bundle node) is used as usual. This only applies to user-defined attributes; the cluster will always check the local node for cluster-defined attributes such as ``#uname``. If ``container-attribute-target`` is ``host``, the cluster will pass additional environment variables to the primitive's resource agent that allow it to set node attributes appropriately: ``CRM_meta_container_attribute_target`` (identical to the meta-attribute value) and ``CRM_meta_physical_host`` (the name of the underlying host). .. note:: When called by a resource agent, the ``attrd_updater`` and ``crm_attribute`` commands will automatically check those environment variables and set attributes appropriately. .. index:: single: bundle; meta-attributes Bundle Meta-Attributes ______________________ Any meta-attribute set on a bundle will be inherited by the bundle's primitive and any resources implicitly created by Pacemaker for the bundle. This includes options such as ``priority``, ``target-role``, and ``is-managed``. See :ref:`resource_options` for more information. Bundles support clone meta-attributes including ``notify``, ``ordered``, and ``interleave``. Limitations of Bundles ______________________ Restarting pacemaker while a bundle is unmanaged or the cluster is in maintenance mode may cause the bundle to fail. Bundles may not be explicitly cloned or included in groups. This includes the bundle's primitive and any resources implicitly created by Pacemaker for the bundle. (If ``replicas`` is greater than 1, the bundle will behave like a clone implicitly.) Bundles do not have instance attributes, utilization attributes, or operations, though a bundle's primitive may have them. A bundle with a primitive can run on a Pacemaker Remote node only if the bundle uses a distinct ``control-port``. .. [#] Of course, the service must support running multiple instances. .. [#] Docker is a trademark of Docker, Inc. No endorsement by or association with Docker, Inc. is implied.