Attachment 231331 Details for Bug 247772 – Updated specification w/ example script which is being tested

Updated specification w/ example script which is being tested

specs.txt (text/plain), 9.06 KB, created by Lon Hohberger on 2007-10-18 17:55:50 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Lon Hohberger

Created: 2007-10-18 17:55:50 UTC

Size: 9.06 KB

patch

obsolete

>Basic configuration specification:
>
>  <rm>
>    <events>
>      <event class="node"/>        
>      <event class="node"
>             node="bar"/>     
>      <event class="node"
>             node="foo"
>             node_state="up"/>     
>      <event class="node"
>             node_id="3"
>             node_state="down"/>   
>
>          (note, all service ops and such deal with node ID, not
>           with node names)
>
>      <event class="service"/>     
>      <event class="service"
>             service_name="A"/>    
>      <event class="service"
>             service_name="B"
>	     service_state="started"/> 
>      <event class="service"
>             service_name="B"
>	     service_state="started"/>
>	     service_owner="3"/> 
>
>      <event class="service"
>             priority="1"
>	     service_state="started"/>
>	     service_owner="3"/> 
>
>
>    </events>
>    ...
>  </rm>
>
>General globals available from all scripts:
>
>   node_self - local node ID
>   event_type - event class, either:
>       EVENT_NONE - unspecified / unknown
>       EVENT_NODE - node transition
>       EVENT_SERVICE - service transition
>
>Node event globals (i.e. when event_type == EVENT_NODE):
>  
>   node_id - node ID which is transitioning
>   node_name - name of node which is transitioning
>   node_state - new node state (NODE_ONLINE or NODE_OFFLINE, or if you prefer,
>                1 or 0, respectively)
>   node_clean - 0 if the node has not been fenced, 1 if the node has been
>                fenced
>
>Service event globals (i.e. when event_type == EVENT_SERVICE):
>
>   service_name - Name of service which transitioned
>   service_state - new state of service
>   service_owner - new owner of service (or <0 if service is no longer
>		   running)
>
>Scripting functions - Informational:
>
>  node_list = nodes_online();
>
>	Returns a list of all online nodes.
>
>  service_list = service_list();
>
>	Returns a list of all configured services.
>
>  (restarts, last_owner, owner, state) = service_status(service_name);
>
>	Returns the state, owner, last_owner, and restarts.  Note that
>	all return values are optional, but are right-justified per S-Lang
>	specification.  This means if you only want the 'state', you can use:
>	
>	(state) = service_status(service_name);
>
>	However, if you need the restart count, you must provide all four 
>	return values as above.
>
>  (nofailback, restricted, ordered, node_list) =
>		service_domain_info(service_name);
>
>	Returns the failover domain specification, if it exists, for the
>	specified service name.  The node list returned is an ordered list
>	according to priority levels.  In the case of unordered domains, 
>	the ordering of the returned list is pseudo-random.
>
>Scripting functions - Operational:
>
>  err = service_start(service_name, node_list, [avoid_list]);
>
>	Start a non-running, (but runnable, i.e. not failed)
>	service on the first node in node_list.  Failing that, start it on
>	the second node in node_list and so forth.  One may also specify
>	an avoid list, but it's better to just use the subtract() function
>	below.
>
>  err = service_stop(service_name, [0 = stop, 1 = disable]);
>
>	Stop a running service.  The second parameter is optional, and if
>	non-zero is specified, the service will enter the disabled state.
>
>  ... stuff that's not done but needs to be:
>
>  err = service_relocate(service_name, node_list);
>
>	Move a running service to the specified node_list in order of
>	preference.  In the case of VMs, this is actually a migrate-or-
>	relocate operation.
>
>Utility functions - Node list manipulation
>
>  node_list = union(left_node_list, right_node_list);
>
>	Calculates the union between the two node list, removing duplicates
>	and preserving ordering according to left_node_list.  Any added
>	values from right_node_list will appear in their order, but
>	after left_node_list in the returned list.
>
>  node_list = intersection(left_node_list, right_node_list);
>
>	Calculates the intersection (items in both lists) between the two
>	node lists, removing duplicates and preserving ordering according
>	to left_node_list.  Any added values from right_node_list will
>	appear in their order, but after left_node_list in the returned list.
>
>  node_list = delta(left_node_list, right_node_list);
>
>	Calculates the delta (items not in both lists) between the two
>	node lists, removing duplicates and preserving ordering according
>	to left_node_list.  Any added values from right_node_list will
>	appear in their order, but after left_node_list in the returned list.
>
>  node_list = subtract(left_node_list, right_node_list);
>
>	Removes any duplicates as well as items specified in right_node_list
>	from left_node_list.  Example:
>
>	all_nodes = nodes_online();
>	allowed_nodes = subtract(nodes_online, node_to_avoid);
>
>Utility functions - Logging:
>
>  debug(item1, item2, ...);	LOG_DEBUG level
>  info(...);			LOG_INFO level
>  notice(...);			LOG_NOTICE level
>  warning(...);			LOG_WARNING level
>  err(...);			LOG_ERR level
>  crit(...);			LOG_CRIT level
>  alert(...);			LOG_ALERT level
>  emerg(...);			LOG_EMERG level
>
>	items - These can be strings, integer lists, or integers.  Logging
>		string lists is not supported.
>
>	level - the level is consistent with syslog(8)
>
>  stop_processing();
>
>	Calling this function will prevent further event scripts from being
>	executed on a particular event.  Call this script if, for example,
>	you do not wish for the default event handler to process the event.
>
>	Note: This does NOT terminate the caller script; that is, the
>	script being executed will run to completion.
>
>Event scripts are written in a language called S-Lang; documentation specifics
>about the language are available at http://www.s-lang.org
>
>Example script (creating a follows-but-avoid-after-start behavior):
>%
>% If the main queue server and replication queue server are on the same
>% node, relocate the replication server somewhere else if possible.
>%
>define my_sap_event_trigger()
>{
>	variable state, owner_rep, owner_main;
>	variable nodes, allowed;
>
>	%
>	% If this was a service event, don't execute the default event
>	% script trigger after this script completes.
>	%
>	if (event_type == EVENT_SERVICE) {
>		stop_processing();
>	}
>
>	(owner_main, state) = service_status("service:main_queue");
>	(owner_rep, state) = service_status("service:replication_server");
>
>	if ((event_type == EVENT_NODE) and (owner_main == node_id) and
>	    (node_state == NODE_OFFLINE) and (owner_rep >= 0)) {
>		%
>		% uh oh, the owner of the main server died.  Restart it
>		% on the node running the replication server
>		%
>		notice("Starting Main Queue Server on node ", owner_rep);
>		()=service_start("service:main_queue", owner_rep);
>		return;
>	}
>
>	%
>	% S-Lang doesn't short-circuit prior to 2.1.0
>	%
>	if ((owner_main >= 0) and
>	    ((owner_main == owner_rep) or (owner_rep < 0))) {
>
>		%
>		% Get all online nodes
>		%
>		nodes = nodes_online();
>
>		%
>		% Drop out the owner of the main server
>		%
>		allowed = subtract(nodes, owner_main);
>		if ((owner_rep >= 0) and (length(allowed) == 0)) {
>			%
>			% Only one node is online and the rep server is
>			% already running.  Don't do anything else.
>			%
>			return;
>		}
>
>		if ((length(allowed) == 0) and (owner_rep < 0)) {
>			%
>			% Only node online is the owner ... go ahead
>			% and start it, even though it doesn't increase
>			% availability to do so.
>			%
>			allowed = owner_main;
>		}
>
>		%
>		% Move the replication server off the node that is
>		% running the main server if a node's available.
>		%
>		if (owner_rep >= 0) {
>			()=service_stop("service:replication_server");
>		}
>		()=service_start("service:replication_server", allowed);
>	}
>
>	return;
>}
>
>my_sap_event_trigger();
>
>
>Relevant <rm> section from cluster.conf:
>
>        <rm central_processing="1">
>                <events>
>                        <event name="main-start" class="service"
>				service="service:main_queue"
>				service_state="started"
>				file="/tmp/sap.sl"/>
>                        <event name="rep-start" class="service"
>				service="service:replication_server"
>				service_state="started"
>				file="/tmp/sap.sl"/>
>                        <event name="node-up" node_state="up"
>				class="node"
>				file="/tmp/sap.sl"/>
>
>                        
>                        <event name="catchall"
>				priority="100"
>			file="/usr/share/cluster/default_event_script.sl"/>
>                </events>
>                <failoverdomains>
>                        <failoverdomain name="all" ordered="1" restricted="1">
>                                <failoverdomainnode name="molly"
>priority="2"/>
>                                <failoverdomainnode name="frederick"
>priority="1"/>
>                        </failoverdomain>
>                </failoverdomains>
>                <resources/>
>                <service name="main_queue"/>
>                <service name="replication_server" autostart="0"/>
>		
>        </rm>
>
>

Actions: View

Attachments on bug 247772: 158940 | 179501 | 231331 | 231411 | 231421 | 253261 | 253271