diff --git a/doc/sphinx/Pacemaker_Administration/agents.rst b/doc/sphinx/Pacemaker_Administration/agents.rst
index 2205e42e62..e65600e797 100644
--- a/doc/sphinx/Pacemaker_Administration/agents.rst
+++ b/doc/sphinx/Pacemaker_Administration/agents.rst
@@ -1,512 +1,518 @@
.. index::
single: resource agent
Resource Agents
---------------
Action Completion
#################
If one resource depends on another resource via constraints, the cluster will
interpret an expected result as sufficient to continue with dependent actions.
This may cause timing issues if the resource agent start returns before the
service is not only launched but fully ready to perform its function, or if the
resource agent stop returns before the service has fully released all its
claims on system resources. At a minimum, the start or stop should not return
before a status command would return the expected (started or stopped) result.
.. index::
single: OCF resource agent
single: resource agent; OCF
OCF Resource Agents
###################
.. index::
single: OCF resource agent; location
Location of Custom Scripts
__________________________
OCF Resource Agents are found in ``/usr/lib/ocf/resource.d/$PROVIDER``
When creating your own agents, you are encouraged to create a new directory
under ``/usr/lib/ocf/resource.d/`` so that they are not confused with (or
overwritten by) the agents shipped by existing providers.
So, for example, if you choose the provider name of big-corp and want a new
resource named big-app, you would create a resource agent called
``/usr/lib/ocf/resource.d/big-corp/big-app`` and define a resource:
.. code-block: xml
.. index::
single: OCF resource agent; action
Actions
_______
All OCF resource agents are required to implement the following actions.
.. list-table:: **Required Actions for OCF Agents**
:class: longtable
:widths: 1 4 3
:header-rows: 1
* - Action
- Description
- Instructions
* - .. _start_action:
.. index::
single: OCF resource agent; start
single: start action
start
- Start the resource
- - Return 0 on success and an appropriate error code otherwise. Must not
- report success until the resource is fully active.
+ - Return :ref:`OCF_SUCCESS ` on success and an appropriate
+ error code otherwise. Must not report success until the resource is fully
+ active.
* - .. _stop_action:
.. index::
single: OCF resource agent; stop
single: stop action
stop
- Stop the resource
- - Return 0 on success and an appropriate error code otherwise. Must not
- report success until the resource is fully stopped.
+ - Return :ref:`OCF_SUCCESS ` on success and an appropriate
+ error code otherwise. Must not report success until the resource is fully
+ stopped.
* - .. _monitor_action:
.. index::
single: OCF resource agent; monitor
single: monitor action
monitor
- Check the resource's state
- - Return 0 if the resource is running, 7 if it is stopped, and any other
- OCF exit code if it is failed. **Note:** The monitor action should test
- the state of the resource on the local machine only.
+ - Return :ref:`OCF_SUCCESS ` if the resource is running,
+ :ref:`OCF_NOT_RUNNING ` if it is stopped, and any other
+ :ref:`OCF exit code ` if it is failed. **Note:** The
+ monitor action should test the state of the resource on the local machine
+ only.
* - .. _meta_data_action:
.. index::
single: OCF resource agent; meta-data
single: meta-data action
meta-data
- Describe the resource
- Provide information about this resource in the XML format defined by the
- OCF standard. Return 0. **Note:** This is *not* required to be performed
- as root.
+ OCF standard. Return :ref:`OCF_SUCCESS `. **Note:** This is
+ *not* required to be performed as root.
OCF resource agents may optionally implement additional actions. Some are used
only with advanced resource types such as clones.
.. list-table:: **Optional Actions for OCF Resource Agents**
:class: longtable:
:widths: 1 4 3
:header-rows: 1
* - Action
- Description
- Instructions
* - .. _validate_all_action:
.. index::
single: OCF resource agent; validate-all
single: validate-all action
validate-all
- Validate the instance parameters provided.
- - Return 0 if parameters are valid, 2 if not valid, and 6 if resource is
- not configured.
+ - Return :ref:`OCF_SUCCESS ` if parameters are valid,
+ :ref:`OCF_ERR_ARGS ` if not valid, and
+ :ref:`OCF_ERR_CONFIGURED ` if resource is not
+ configured.
* - .. _promote_action:
.. index::
single: OCF resource agent; promote
single: promote action
promote
- Bring the local instance of a promotable clone resource to the promoted
role.
- - Return 0 on success.
+ - Return :ref:`OCF_SUCCESS ` on success.
* - .. _demote_action:
.. index::
single: OCF resource agent; demote
single: demote action
demote
- Bring the local instance of a promotable clone resource to the unpromoted
role.
- - Return 0 on success.
+ - Return :ref:`OCF_SUCCESS ` on success.
* - .. _notify_action:
.. index::
single: OCF resource agent; notify
single: notify action
notify
- Used by the cluster to send the agent pre- and post-notification events
telling the resource what has happened and what will happen.
- - Must not fail. Must return 0.
+ - Must not fail. Must return :ref:`OCF_SUCCESS `.
* - .. _reload_action:
.. index::
single: OCF resource agent; reload
single: reload action
reload
- Reload the service's own configuration.
- Not used by Pacemaker.
* - .. _reload_agent_action:
.. index::
single: OCF resource agent; reload-agent
single: reload-agent action
reload-agent
- Make effective any changes in instance parameters marked as reloadable in
the agent's meta-data.
- This is used when the agent can handle a change in some of its parameters
more efficiently than stopping and starting the resource.
* - .. _recover_action:
.. index::
single: OCF resource agent; recover
single: recover action
recover
- Restart the service.
- Not used by Pacemaker.
.. important::
If you create a new OCF resource agent, use `ocf-tester` to verify that the
agent complies with the OCF standard properly.
.. index::
single: OCF resource agent; return code
How Are OCF Return Codes Interpreted?
_____________________________________
The first thing the cluster does is to check the return code against the
expected result. If the result does not match the expected value, then the
operation is considered to have failed, and recovery action is initiated.
There are three types of failure recovery:
.. list-table:: **Types of Recovery Performed by the Cluster**
:class: longtable
:widths: 1 5 5
:header-rows: 1
* - Type
- Description
- Action Taken by the Cluster
* - .. _soft_error:
.. index::
single: OCF resource agent; soft error
soft
- A transient error
- Restart the resource or move it to a new location
* - .. _hard_error:
.. index::
single: OCF resource agent; hard error
hard
- A non-transient error that may be specific to the current node
- Move the resource elsewhere and prevent it from being retried on the
current node
* - .. _fatal_error:
.. index::
single: OCF resource agent; fatal error
fatal
- A non-transient error that will be common to all cluster nodes (for
example, a bad configuration was specified)
- Stop the resource and prevent it from being started on any cluster node
.. _ocf_return_codes:
OCF Return Codes
________________
The following table outlines the various OCF return codes and the type of
recovery the cluster will initiate when a failure code is received. Although
counterintuitive, even actions that return ``OCF_SUCCESS`` can be considered to
have failed, if ``OCF_SUCCESS`` was not the expected return value.
.. list-table:: **OCF Exit Codes and Their Recovery Types**
:class: longtable
:widths: 1 3 6 2
:header-rows: 1
* - Exit Code
- OCF Alias
- Description
- Recovery
* - .. _OCF_SUCCESS:
.. index::
single: OCF_SUCCESS
single: OCF return code; OCF_SUCCESS
pair: OCF return code; 0
0
- OCF_SUCCESS
- Success. The command completed successfully. This is the expected result
for all start, stop, promote, and demote actions.
- :ref:`soft `
* - .. _OCF_ERR_GENERIC:
.. index::
single: OCF_ERR_GENERIC
single: OCF return code; OCF_ERR_GENERIC
pair: OCF return code; 1
1
- OCF_ERR_GENERIC
- Generic "there was a problem" error code.
- :ref:`hard `
* - .. _OCF_ERR_ARGS:
.. index::
single: OCF_ERR_ARGS
single: OCF return code; OCF_ERR_ARGS
pair: OCF return code; 2
2
- OCF_ERR_ARGS
- The resource's parameter values are not valid on this machine (for
example, a value refers to a file not found on the local host).
- :ref:`hard `
* - .. _OCF_ERR_UNIMPLEMENTED:
.. index::
single: OCF_ERR_UNIMPLEMENTED
single: OCF return code; OCF_ERR_UNIMPLEMENTED
pair: OCF return code; 3
3
- OCF_ERR_UNIMPLEMENTED
- The requested action is not implemented.
- :ref:`hard `
* - .. _OCF_ERR_PERM:
.. index::
single: OCF_ERR_PERM
single: OCF return code; OCF_ERR_PERM
pair: OCF return code; 4
4
- OCF_ERR_PERM
- The resource agent does not have sufficient privileges to complete the
task.
- :ref:`hard `
* - .. _OCF_ERR_INSTALLED:
.. index::
single: OCF_ERR_INSTALLED
single: OCF return code; OCF_ERR_INSTALLED
pair: OCF return code; 5
5
- OCF_ERR_INSTALLED
- The tools required by the resource are not installed on this machine.
- :ref:`hard `
* - .. _OCF_ERR_CONFIGURED:
.. index::
single: OCF_ERR_CONFIGURED
single: OCF return code; OCF_ERR_CONFIGURED
pair: OCF return code; 6
6
- OCF_ERR_CONFIGURED
- The resource's parameter values are inherently invalid (for example, a
required parameter was not given).
- :ref:`fatal `
* - .. _OCF_NOT_RUNNING:
.. index::
single: OCF_NOT_RUNNING
single: OCF return code; OCF_NOT_RUNNING
pair: OCF return code; 7
7
- OCF_NOT_RUNNING
- The resource is safely stopped. This should only be returned by monitor
actions, not stop actions.
- N/A
* - .. _OCF_RUNNING_PROMOTED:
.. index::
single: OCF_RUNNING_PROMOTED
single: OCF return code; OCF_RUNNING_PROMOTED
pair: OCF return code; 8
8
- OCF_RUNNING_PROMOTED
- The resource is running in the promoted role.
- :ref:`soft `
* - .. _OCF_FAILED_PROMOTED:
.. index::
single: OCF_FAILED_PROMOTED
single: OCF return code; OCF_FAILED_PROMOTED
pair: OCF return code; 9
9
- OCF_FAILED_PROMOTED
- The resource is (or might be) in the promoted role but has failed. The
resource will be demoted, stopped, and then started (and possibly
promoted) again.
- :ref:`soft `
* - .. _OCF_DEGRADED:
.. index::
single: OCF_DEGRADED
single: OCF return code; OCF_DEGRADED
pair: OCF return code; 190
190
- OCF_DEGRADED
- The resource is properly active, but in such a condition that future
failures are more likely.
- none
* - .. _OCF_DEGRADED_PROMOTED:
.. index::
single: OCF_DEGRADED_PROMOTED
single: OCF return code; OCF_DEGRADED_PROMOTED
pair: OCF return code; 191
191
- OCF_DEGRADED_PROMOTED
- The resource is properly active in the promoted role, but in such a
condition that future failures are more likely.
- none
* - other
- *none*
- Custom error code.
- soft
Exceptions to the recovery handling described above:
* Probes (non-recurring monitor actions) that find a resource active
(or in the promoted role) will not result in recovery action unless it is
also found active elsewhere.
* The recovery action taken when a resource is found active more than
once is determined by the resource's ``multiple-active`` property.
* Recurring actions that return ``OCF_ERR_UNIMPLEMENTED``
do not cause any type of recovery.
* Actions that return one of the "degraded" codes will be treated the same as
if they had returned success, but status output will indicate that the
resource is degraded.
.. index::
single: resource agent; LSB
single: LSB resource agent
single: init script
LSB Resource Agents (Init Scripts)
##################################
LSB Compliance
______________
The relevant part of the
`LSB specifications `_
includes a description of all the return codes listed here.
Assuming `some_service` is configured correctly and currently
inactive, the following sequence will help you determine if it is
LSB-compatible:
#. Start (stopped):
.. code-block:: none
# /etc/init.d/some_service start ; echo "result: $?"
* Did the service start?
* Did the echo command print ``result: 0`` (in addition to the init script's
usual output)?
#. Status (running):
.. code-block:: none
# /etc/init.d/some_service status ; echo "result: $?"
* Did the script accept the command?
* Did the script indicate the service was running?
* Did the echo command print ``result: 0`` (in addition to the init script's
usual output)?
#. Start (running):
.. code-block:: none
# /etc/init.d/some_service start ; echo "result: $?"
* Is the service still running?
* Did the echo command print ``result: 0`` (in addition to the init
script's usual output)?
#. Stop (running):
.. code-block:: none
# /etc/init.d/some_service stop ; echo "result: $?"
* Was the service stopped?
* Did the echo command print ``result: 0`` (in addition to the init
script's usual output)?
#. Status (stopped):
.. code-block:: none
# /etc/init.d/some_service status ; echo "result: $?"
* Did the script accept the command?
* Did the script indicate the service was not running?
* Did the echo command print ``result: 3`` (in addition to the init
script's usual output)?
#. Stop (stopped):
.. code-block:: none
# /etc/init.d/some_service stop ; echo "result: $?"
* Is the service still stopped?
* Did the echo command print ``result: 0`` (in addition to the init
script's usual output)?
#. Status (failed):
This step is not readily testable and relies on manual inspection of the script.
The script can use one of the error codes (other than 3) listed in the
LSB spec to indicate that it is active but failed. This tells the
cluster that before moving the resource to another node, it needs to
stop it on the existing one first.
If the answer to any of the above questions is no, then the script is not
LSB-compliant. Your options are then to either fix the script or write an OCF
agent based on the existing script.