Zabbix Documentation 3.4

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manual:discovery:low_level_discovery

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manual:discovery:low_level_discovery [2015/06/15 06:35]
Igors H [3.6 Discovery of Windows services] added info about windows services
manual:discovery:low_level_discovery [2019/06/07 07:49]
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-==== - #3 Low-level discovery ==== 
  
-=== Overview === 
- 
-Low-level discovery provides a way to automatically create items, triggers, and graphs for different entities on a computer. For instance, Zabbix can automatically start monitoring file systems or network interfaces on your machine, without the need to create items for each file system or network interface manually. Additionally it is possible to configure Zabbix to remove unneeded entities automatically based on actual results of periodically performed discovery. 
- 
-In Zabbix, five types of item discovery are supported out of the box: 
- 
-  * discovery of file systems; 
-  * discovery of network interfaces; 
-  * discovery of CPUs and CPU cores; 
-  * discovery of SNMP OIDs; 
-  * discovery using ODBC SQL queries. 
-  * discovery of Windows services 
- 
-A user can define their own types of discovery, provided they follow a particular JSON protocol. 
- 
-The general architecture of the discovery process is as follows. 
- 
-First, a user creates a discovery rule in "​Configuration"​ -> "​Templates"​ -> "​Discovery"​ column. A discovery rule consists of (1) an item that discovers the necessary entities (for instance, file systems or network interfaces) and (2) prototypes of items, triggers, and graphs that should be created based on the value of that item. 
- 
-An item that discovers the necessary entities is like a regular item seen elsewhere: the server asks a Zabbix agent (or whatever the type of the item is set to) for a value of that item, the agent responds with a textual value. The difference is that the value the agent responds with should contain a list of discovered entities in a specific JSON format. While the details of this format are only important for implementers of custom discovery checks, it is necessary to know that the returned value contains a list of macro -> value pairs. For instance, item "​net.if.discovery"​ might return two pairs: "​{#​IFNAME}"​ -> "​lo"​ and "​{#​IFNAME}"​ -> "​eth0"​. 
- 
-<​note>​Low-level discovery items "​vfs.fs.discovery"​ and "​net.if.discovery"​ are supported since Zabbix agent version 2.0.\\ Discovery item "​system.cpu.discovery"​ is supported since Zabbix agent version 2.4.\\ Discovery of SNMP OIDs is supported since Zabbix server and proxy version 2.0.\\ Discovery using ODBC SQL queries is supported since Zabbix server and proxy version 3.0.</​note>​ 
- 
-<​note>​Return values of a low-level discovery rule are limited to 2048 bytes on a Zabbix proxy run with IBM DB2 database. This limit does not apply to Zabbix server as return values are processed without being stored in a database.</​note>​ 
- 
-These macros are then used in names, keys, and other prototype fields that are basis for creating real items, triggers, and graphs for each discovered entity. These macros can be used: 
- 
-  * for item prototypes in 
-    * names 
-    * key parameters 
-    * IPMI sensor 
-    * SNMP OIDs 
-    * units 
-    * calculated item formulas 
-    * SSH and Telnet scripts 
-    * database monitor item parameters 
-    * descriptions (supported since 2.2.0) 
-  * for trigger prototypes in 
-    * names 
-    * expressions (insofar as when referencing an item key prototype and as standalone constants) ​ 
-    * URLs (supported since 3.0.0) 
-    * descriptions (supported since 2.2.0) 
-  * for graph prototypes in 
-    * names 
- 
-When the server receives a value for a discovery item, it looks at the macro -> value pairs and for each pair generates real items, triggers, and graphs, based on their prototypes. In the example with "​net.if.discovery"​ above, the server would generate one set of items, triggers, and graphs for the loopback interface "​lo",​ and another set for interface "​eth0"​. 
- 
-The following sections illustrate the process described above in detail and serve as a how-to for performing all types of discovery mentioned above. The last section describes the JSON format for discovery items and gives an example of how to implement your own file system discoverer as a Perl script. 
- 
-=== - Discovery of file systems === 
- 
-To configure the discovery of file systems, do the following: 
- 
-  * Go to: //​Configuration//​ -> //​Templates// ​ 
-  * Click on //​Discovery//​ in the row of an appropriate template 
- 
-{{manual:​discovery:​low_level_discovery:​fs_templates.png|}} 
- 
-  * Click on //Create discovery rule// in the upper right corner of the screen 
-  * Fill in the form with the following details 
- 
-The **Discovery rule** tab contains general discovery rule attributes: ​ 
- 
-{{manual:​discovery:​low_level_discovery:​lld_rule_fs.png|}} 
- 
-^Parameter^Description^ 
-|//​Name// ​ |Name of discovery rule.  | 
-|//​Type// ​ |The type of check to perform discovery; should be //Zabbix agent// or //Zabbix agent (active)// for file system discovery. ​ | 
-|//​Key// ​ |An item with "​vfs.fs.discovery"​ key is built into the Zabbix agent on many platforms (see [[manual:​appendix:​items:​supported_by_platform|supported item key list]] for details), and will return a JSON with the list of file systems present on the computer and their types. ​ | 
-|//Update interval (in sec)// ​ |This field specifies how often Zabbix performs discovery. In the beginning, when you are just setting up file system discovery, you might wish to set it to a small interval, but once you know it works you can set it to 30 minutes or more, because file systems usually do not change very often.\\ //Note//: If set to '​0',​ the item will not be polled. However, if a flexible interval also exists with a non-zero value, the item will be polled during the flexible interval duration. ​ | 
-|//Flexible intervals// ​ |You can create exceptions to //Update interval//. For example:\\ Interval: **0**, Period: **6-7,​00:​00-24:​00** - will disable the polling at the weekend. Otherwise default update interval will be used.\\ Up to seven flexible intervals can be defined.\\ If multiple flexible intervals overlap, the smallest //​Interval//​ value is used for the overlapping period.\\ See [[manual:​appendix:​time_period|Time period specification]] page for description of the //Period// format.\\ //Note//: If set to '​0',​ the item will not be polled during the flexible interval duration and will resume polling according to the //Update interval// once the flexible interval period is over.  | 
-|//Keep lost resources period (in days)// ​ |This field allows you to specify for how many days the discovered entity will be retained (won't be deleted) once its discovery status becomes "Not discovered anymore"​ (max 3650 days). \\ //Note:// If set to "​0",​ entities will be deleted immediately. Using "​0"​ is not recommended,​ since just wrongly editing the filter may end up in the entity being deleted with all the historical data.   | 
-|//​Description// ​ |Enter a description. ​ | 
-|//​Enabled// ​ |If checked, the rule will be processed. ​ | 
- 
-The **Filters** tab contains discovery rule filter definitions: ​ 
- 
-{{manual:​discovery:​low_level_discovery:​lld_rule_fs2.png|}} 
- 
-^Parameter^Description^ 
-|//Type of calculation// ​ |The following options for calculating filters are available:​\\ **And** - all filters must be passed;\\ **Or** - enough if one filter is passed;\\ **And/Or** - uses //And// with different macro names and //Or// with the same macro name;\\ **Custom expression** - offers the possibility to define a custom calculation of filters. The formula must include all filters in the list. Limited to 255 symbols. ​ | 
-|//​Filters// ​ |A filter can be used to generate real items, triggers, and graphs only for certain file systems. It expects a [[manual:​regular_expressions|POSIX Extended Regular Expression]]. For instance, if you are only interested in C:, D:, and E: file systems, you could put {#FSNAME} into "​Macro"​ and <​nowiki>"​^C|^D|^E"</​nowiki>​ regular expression into "​Regular expression"​ text fields. Filtering is also possible by file system types using {#FSTYPE} macro (e.g. <​nowiki>"​^ext|^reiserfs"</​nowiki>​) and by drive types (supported only by Windows agent) using {#​FSDRIVETYPE} macro (e.g., <​nowiki>"​fixed"</​nowiki>​).\\ You can enter a regular expression or reference a global [[manual:​regular_expressions|regular expression]] in "​Regular expression"​ field.\\ In order to test a regular expression you can use "grep -E", for example: <code bash>for f in ext2 nfs reiserfs smbfs; do echo $f | grep -E '​^ext|^reiserfs'​ || echo "SKIP: $f"; done</​code>​{#​FSDRIVETYPE} macro on Windows is supported since Zabbix **3.0.0**.\\ Defining several filters is supported since Zabbix **2.4.0**.\\ Note that if some macro from the filter is missing in the response, the found entity will be ignored. ​ | 
- 
-<note important>​Zabbix database in MySQL must be created as case-sensitive if file system names that differ only by case are to be discovered correctly.</​note>​ 
- 
-<​note>​Discovery rule history is not preserved.</​note>​ 
- 
-Once a rule is created, go to the items for that rule and press "​Create prototype"​ to create an item prototype. Note how macro {#FSNAME} is used where a file system name is required. When the discovery rule is processed, this macro will be substituted with the discovered file system. 
- 
-{{manual:​discovery:​low_level_discovery:​item_prototype_fs.png|}} 
- 
-<​note>​If an item prototype is created with a //​Disabled//​ status, it will be added to a discovered entity, but in a disabled state.</​note>​ 
- 
-We can create several item prototypes for each file system metric we are interested in: 
- 
-{{manual:​discovery:​low_level_discovery:​item_prototypes_fs.png|}} 
- 
-Then, we create trigger prototypes in a similar way: 
- 
-{{manual:​discovery:​low_level_discovery:​trigger_prototype_fs.png|}} 
- 
-{{manual:​discovery:​low_level_discovery:​trigger_prototypes_fs.png|}} 
- 
-And graph prototypes too: 
- 
-{{manual:​discovery:​low_level_discovery:​graph_prototype_fs.png|}} 
- 
-{{manual:​discovery:​low_level_discovery:​graph_prototypes_fs.png|}} 
- 
-Finally, we have created a discovery rule that looks like shown below. It has five item prototypes, two trigger prototypes, and one graph prototype. 
- 
-{{manual:​discovery:​low_level_discovery:​lld_rules_fs.png|}} 
- 
-//Note//: For configuring host prototypes, see the section about [[:​manual/​vm_monitoring#​host_prototypes|host prototype]] configuration in virtual machine monitoring. 
- 
-The screenshots below illustrate how discovered items, triggers, and graphs look like in the host's configuration. Discovered entities are prefixed with a golden link to a discovery rule they come from. 
- 
-{{manual:​discovery:​low_level_discovery:​discovered_items.png|}} 
- 
-Note that discovered entities will not be created in case there are already existing entities with the same uniqueness criteria, for example, an item with the same key or graph with the same name. 
- 
-Items (similarly, triggers and graphs) created by a low-level discovery rule cannot be manually deleted. However, they will be deleted automatically if a discovered entity (file system, interface, etc) stops being discovered (or does not pass the filter anymore). In this case the items, triggers and graphs will be deleted after the days defined in the //Keep lost resources period// field pass. 
- 
-When discovered entities become 'Not discovered anymore',​ an orange lifetime indicator is displayed in the items list. Move your mouse pointer over it and a message will be displayed indicating how many days are left until the item will be deleted. 
- 
-{{1.9.9_lifetime_indicator.png|}} 
- 
-If entities were marked for deletion, but were not deleted at the expected time (disabled discovery rule or item host), they will be deleted the next time the discovery rule is processed. 
- 
-{{manual:​discovery:​low_level_discovery:​discovered_triggers.png|}} 
- 
-{{manual:​discovery:​low_level_discovery:​discovered_graphs.png|}} 
- 
-=== - Discovery of network interfaces === 
- 
-Discovery of network interfaces is done in exactly the same way as discovery of file systems, except that you use the discovery rule key "​net.if.discovery"​ instead of "​vfs.fs.discovery"​ and use macro {#IFNAME} instead of {#FSNAME} in filter and item/​trigger/​graph prototypes. 
- 
-Examples of item prototypes that you might wish to create based on "​net.if.discovery":​ "​net.if.in[{#​IFNAME},​bytes]",​ "​net.if.out[{#​IFNAME},​bytes]"​. 
- 
-[[#​discovery_of_file_systems|See above]] for more information about the filter. 
- 
-=== - Discovery of CPUs and CPU cores === 
- 
-Discovery of CPUs and CPU cores is done in a similar fashion as network interface discovery with the exception being that the discovery rule key is "​system.cpu.discovery"​. This discovery key returns two macros - {#​CPU.NUMBER} and {#​CPU.STATUS} identifying the CPU order number and status respectively. To note, a clear distinction cannot be made between actual, physical processors, cores and hyperthreads. {#​CPU.STATUS} on Linux, UNIX and BSD systems returns the status of the processor, which can be either "​online"​ or "​offline"​. On Windows systems, this same macro may represent a third value - "​unknown"​ - which indicates that a processor has been detected, but no information has been collected for it yet. 
- 
-CPU discovery relies on the agent'​s collector process to remain consistent with the data provided by the collector and save resources on obtaining the data. This has the effect of this item key not working with the test (-t) command line flag of the agent binary, which will return a NOT_SUPPORTED status and an accompanying message indicating that the collector process has not been started. 
- 
-Item prototypes that can be created based on CPU discovery include "​system.cpu.load[{#​CPU.NUMBER},​ <​mode>​]",​ "​system.cpu.util[{#​CPU.NUMBER},​ <​type>,​ <​mode>​]"​ et al. 
- 
-=== - Discovery of SNMP OIDs === 
- 
-In this example, we will perform SNMP discovery on a switch. First, go to "​Configuration"​ -> "​Templates"​. 
- 
-{{manual:​discovery:​low_level_discovery:​templates_snmp.png|}} 
- 
-To edit discovery rules for a template, click on the link in the "​Discovery"​ column. 
- 
-Then, press "​Create rule" and fill the form with the details in the screenshot below. 
- 
-Unlike file system and network interface discovery, the item does not necessarily have to have "​snmp.discovery"​ key - item type of SNMP agent is sufficient. 
- 
-The OIDs to discover are defined in SNMP OID field in the following format: ''​discovery[{#​MACRO1},​ oid1, {#MACRO2}, oid2, …,​]''​ 
- 
-where //​{#​MACRO1}//,​ //​{#​MACRO2}//​ …  are valid lld macro names and //oid1//, //oid2//... are OIDs capable of generating meaningful values for these macros. A built-in macro //​{#​SNMPINDEX}//​ containing index of the discovered OID is applied to discovered entities. The discovered entities are grouped by //​{#​SNMPINDEX}//​ macro value. 
- 
-To understand what we mean, let us perform few snmpwalks on our switch: ​ 
-  $ snmpwalk -v 2c -c public 192.168.1.1 IF-MIB::​ifDescr 
-  IF-MIB::​ifDescr.1 = STRING: WAN 
-  IF-MIB::​ifDescr.2 = STRING: LAN1 
-  IF-MIB::​ifDescr.3 = STRING: LAN2 
-  ​ 
-  $ snmpwalk -v 2c -c public 192.168.1.1 IF-MIB::​ifPhysAddress 
-  IF-MIB::​ifPhysAddress.1 = STRING: 8:​0:​27:​90:​7a:​75 
-  IF-MIB::​ifPhysAddress.2 = STRING: 8:​0:​27:​90:​7a:​76 
-  IF-MIB::​ifPhysAddress.3 = STRING: 8:​0:​27:​2b:​af:​9e 
- 
-And set SNMP OID to: ''​discovery[{#​IFDESCR},​ ifDescr, {#​IFPHYSADDRESS},​ ifPhysAddress]''​ 
- 
-Now this rule will discover entities with {#IFDESCR} macros set to **WAN**, **LAN1** and **LAN2**, {#​IFPHYSADDRESS} macros set to **8:​0:​27:​90:​7a:​75**,​ **8:​0:​27:​90:​7a:​76**,​ and **8:​0:​27:​2b:​af:​9e**,​ {#​SNMPINDEX} macros set to the discovered OIDs indexes **1**, **2** and **3**: 
-  { 
-      "​data":​ [ 
-          { 
-              "​{#​SNMPINDEX}":​ "​1",​ 
-              "​{#​IFDESCR}":​ "​lo",​ 
-              "​{#​IFPHYSADDRESS}":​ "​8:​0:​27:​90:​7a:​75"​ 
-          }, 
-          { 
-              "​{#​SNMPINDEX}":​ "​2",​ 
-              "​{#​IFDESCR}":​ "​eth1",​ 
-              "​{#​IFPHYSADDRESS}":​ "​8:​0:​27:​90:​7a:​75"​ 
-          }, 
-          { 
-              "​{#​SNMPINDEX}":​ "​3",​ 
-              "​{#​IFDESCR}":​ "​eth0",​ 
-              "​{#​IFPHYSADDRESS}":​ "​8:​0:​27:​2b:​af:​9e"​ 
-          } 
-      ] 
-  } 
- 
-If an entity does not have the specified OID, then the corresponding macro will be omitted for this entity. For example if we have the following data: 
-  ifDescr.1 "​Interface #1" 
-  ifDescr.2 "​Interface #2" 
-  ifDescr.4 "​Interface #4" 
-  ​ 
-  ifAlias.1 "​eth0"​ 
-  ifAlias.2 "​eth1"​ 
-  ifAlias.3 "​eth2"​ 
-  ifAlias.5 "​eth4"​ 
-  
-Then in this case SNMP discovery ''​discovery[{#​IFDESCR},​ ifDescr, {#IFALIAS}, ifAlias]''​ will return the following structure: ​ 
-  { 
-      "​data":​ [ 
-          { 
-              "​{#​SNMPINDEX}":​ 1, 
-              "​{#​IFDESCR}":​ "​Interface #1", 
-              "​{#​IFALIAS}":​ "​eth0"​ 
-          }, 
-          { 
-              "​{#​SNMPINDEX}":​ 2, 
-              "​{#​IFDESCR}":​ "​Interface #2", 
-              "​{#​IFALIAS}":​ "​eth1"​ 
-          }, 
-          { 
-              "​{#​SNMPINDEX}":​ 3, 
-              "​{#​IFALIAS}":​ "​eth2"​ 
-          }, 
-          { 
-              "​{#​SNMPINDEX}":​ 4, 
-              "​{#​IFDESCR}":​ "​Interface #4" 
-          }, 
-          { 
-              "​{#​SNMPINDEX}":​ 5, 
-              "​{#​IFALIAS}":​ "​eth4"​ 
-          } 
-      ] 
-  }  ​ 
- 
-{{manual:​discovery:​low_level_discovery:​lld_rule_snmp.png|}} 
- 
-The following screenshot illustrates how we can use these macros in item prototypes: 
- 
-{{manual:​discovery:​low_level_discovery:​item_prototype_snmp.png|}} 
- 
-Again, creating as many item prototypes as needed: 
- 
-{{manual:​discovery:​low_level_discovery:​item_prototypes_snmp.png|}} 
- 
-As well as trigger prototypes: 
- 
-{{manual:​discovery:​low_level_discovery:​trigger_prototype_snmp.png|}} 
- 
-{{manual:​discovery:​low_level_discovery:​trigger_prototypes_snmp.png|}} 
- 
-And graph prototypes: 
- 
-{{manual:​discovery:​low_level_discovery:​graph_prototype_snmp.png|}} 
- 
-{{manual:​discovery:​low_level_discovery:​graph_prototypes_snmp.png|}} 
- 
-A summary of our discovery rule: 
- 
-{{manual:​discovery:​low_level_discovery:​lld_rules_snmp.png?​600|}} 
- 
-When server runs, it will create real items, triggers, and graphs, based on the values "​snmp.discovery"​ returns. In host's configuration they will be prefixed with a golden link to a discovery rule they come from. 
- 
-{{manual:​discovery:​low_level_discovery:​discovered_items_snmp.png|}} 
- 
-{{manual:​discovery:​low_level_discovery:​discovered_triggers_snmp.png|}} 
- 
-{{manual:​discovery:​low_level_discovery:​discovered_graphs_snmp.png|}} 
- 
-=== - Discovery using ODBC SQL queries === 
- 
-This type of discovery is done using SQL queries, whose results get automatically transformed into a JSON object suitable for low-level discovery. SQL queries are performed using items of type "​Database monitor"​. Therefore, most of the instructions on [[:​manual/​config/​items/​itemtypes/​odbc_checks|ODBC monitoring]] page apply in order to get a working "​Database monitor"​ discovery rule, the only difference being that "​db.odbc.discovery[<​description>,<​dsn>​]"​ key should be used instead of "​db.odbc.select[<​description>,<​dsn>​]"​. 
- 
-As a practical example to illustrate how the SQL query is transformed into JSON, let us consider low-level discovery of Zabbix proxies by performing an ODBC query on Zabbix database. This is useful for automatic creation of "​zabbix[proxy,<​name>,​lastaccess]"​ [[:​manual/​config/​items/​itemtypes/​internal|internal items]] to monitor which proxies are alive. 
- 
-Let us start with discovery rule configuration:​ 
- 
-{{manual:​discovery:​low_level_discovery:​discovery_rule_odbc.png}} 
- 
-Here, the following direct query on Zabbix database is used to select all Zabbix proxies, together with the number of hosts they are monitoring. The number of hosts can be used, for instance, to filter out empty proxies: 
- 
-<​code>​ 
-mysql> SELECT h1.host, COUNT(h2.host) AS count FROM hosts h1 LEFT JOIN hosts h2 ON h1.hostid = h2.proxy_hostid WHERE h1.status IN (5, 6) GROUP BY h1.host; 
-+---------+-------+ 
-| host    | count | 
-+---------+-------+ 
-| Japan 1 |     5 | 
-| Japan 2 |    12 | 
-| Latvia ​ |     3 | 
-+---------+-------+ 
-3 rows in set (0.01 sec) 
-</​code>​ 
- 
-By the internal workings of "​db.odbc.discovery[]"​ item, the result of this query gets automatically transformed into the following JSON: 
- 
-<code js> 
-{ 
-    "​data":​ [ 
-        { 
-            "​{#​HOST}":​ "Japan 1", 
-            "​{#​COUNT}":​ "​5"​ 
-        }, 
-        { 
-            "​{#​HOST}":​ "Japan 2", 
-            "​{#​COUNT}":​ "​12"​ 
-        }, 
-        { 
-            "​{#​HOST}":​ "​Latvia",​ 
-            "​{#​COUNT}":​ "​3"​ 
-        } 
-    ] 
-} 
-</​code>​ 
- 
-It can be seen that column names become macro names and selected rows become the values of these macros. 
- 
-<​note>​ 
-If it is not obvious how a column name would be transformed into a macro name, it is suggested to use column aliases like "​COUNT(h2.host) AS count" in the example above. 
- 
-In case a column name cannot be converted into a valid macro name, the discovery rule becomes not supported, with the error message detailing the offending column number. If additional help is desired, the obtained column names are provided under DebugLevel=4 in Zabbix server log file: 
- 
-<​code>​ 
-$ grep db.odbc.discovery /​tmp/​zabbix_server.log 
- ... 
- ​23876:​20150114:​153410.856 In db_odbc_discovery() query:'​SELECT h1.host, COUNT(h2.host) FROM hosts h1 LEFT JOIN hosts h2 ON h1.hostid = h2.proxy_hostid WHERE h1.status IN (5, 6) GROUP BY h1.host;'​ 
- ​23876:​20150114:​153410.860 db_odbc_discovery() column[1]:'​host'​ 
- ​23876:​20150114:​153410.860 db_odbc_discovery() column[2]:'​COUNT(h2.host)'​ 
- ​23876:​20150114:​153410.860 End of db_odbc_discovery():​NOTSUPPORTED 
- ​23876:​20150114:​153410.860 Item [Zabbix server:​db.odbc.discovery[proxies,​{$DSN}]] error: Cannot convert column #2 name to macro. 
-</​code>​ 
-</​note>​ 
- 
-Now that we understand how a SQL query is transformed into a JSON object, we can use {#HOST} macro in item prototypes: 
- 
-{{manual:​discovery:​low_level_discovery:​item_prototype_odbc.png}} 
- 
-Once discovery is performed, an item will be created for each proxy: 
- 
-{{manual:​discovery:​low_level_discovery:​discovered_items_odbc.png}} 
- 
-=== - Discovery of Windows services === 
- 
-Discovery of Windows services is done in exactly the same way as discovery of file systems. The discovery rule key is "​service.discovery"​ and the following macros are supported in filter and item/​trigger/​graph prototypes: 
- 
-<​code>​ 
-#​SERVICE.NAME 
-#​SERVICE.DISPLAYNAME 
-#​SERVICE.DESCRIPTION 
-#​SERVICE.STATE 
-#​SERVICE.STATENAME 
-#​SERVICE.PATH 
-#​SERVICE.USER 
-#​SERVICE.STARTUP 
-#​SERVICE.STARTUPNAME 
-</​code>​ 
- 
-THe item prototype that can be created based on Windows service discovery is "​service.info[{#​SERVICE.NAME},​ <​param>​]",​ where //param// field can accept the following: //​displayname//,​ //state//, //path//, //user//, //startup// or //​description//​. For example, item "​service.info[{#​SERVICE.NAME},​ displayname]"​ should be used to acquire the display name of a service. The default parameter is //state// if //param// value is not specified ("​service.info[{#​SERVICE.NAME}]"​). ​ 
- 
-Macro #​SERVICE.STATE and macro #​SERVICE.STATENAME return the same values - #​SERVICE.STATE returns numerical value (0-7), but #​SERVICE.STATENAME returns text (running, paused, start pending, pause pending, continue pending, stop pending, stopped or unknown). The same applies to #​SERVICE.STARTUP (0-4) and #​SERVICE.STARTUPNAME (automatic, automatic delayed, manual, disabled, unknown). 
- 
-[[#​discovery_of_file_systems|See above]] for more information about the filter. 
-=== - Creating custom LLD rules === 
- 
-It is also possible to create a completely custom LLD rule, discovering any type of entities - for example, databases on a database server. 
- 
-To do so, a custom item should be created that returns JSON, specifying found objects and optionally - some properties of them. The amount of macros per entity is not limited - while the built-in discovery rules return either one or two macros (for example, two for filesystem discovery), it is possible to return more. 
- 
-The required JSON format is best illustrated with an example. Suppose we are running an old Zabbix 1.8 agent (one that does not support "​vfs.fs.discovery"​),​ but we still need to discover file systems. Here is a simple Perl script for Linux that discovers mounted file systems and outputs JSON, which includes both file system name and type. One way to use it would be as a UserParameter with key "​vfs.fs.discovery_perl":​ 
- 
-<code perl> 
-#​!/​usr/​bin/​perl 
- 
-$first = 1; 
- 
-print "​{\n";​ 
-print "​\t\"​data\":​[\n\n";​ 
- 
-for (`cat /​proc/​mounts`) 
-{ 
-    ($fsname, $fstype) = m/\S+ (\S+) (\S+)/; 
-    $fsname =~ s!/!\\/!g; 
- 
-    print "​\t,​\n"​ if not $first; 
-    $first = 0; 
- 
-    print "​\t{\n";​ 
-    print "​\t\t\"​{#​FSNAME}\":​\"​$fsname\",​\n";​ 
-    print "​\t\t\"​{#​FSTYPE}\":​\"​$fstype\"​\n";​ 
-    print "​\t}\n";​ 
-} 
- 
-print "​\n\t]\n";​ 
-print "​}\n";​ 
-</​code>​ 
- 
-<note important>​Allowed symbols for LLD macro names are **0-9** , **A-Z** , **_** , **.** \\ \\  Lowercase letters are not supported in the names.</​note>​ 
- 
-An example of its output (reformatted for clarity) is shown below. JSON for custom discovery checks has to follow the same format. 
- 
-  { 
-    "​data":​[ 
-    ​ 
-    { "​{#​FSNAME}":"​\/", ​                          "​{#​FSTYPE}":"​rootfs" ​  }, 
-    { "​{#​FSNAME}":"​\/​sys", ​                       "​{#​FSTYPE}":"​sysfs" ​   }, 
-    { "​{#​FSNAME}":"​\/​proc", ​                      "​{#​FSTYPE}":"​proc" ​    }, 
-    { "​{#​FSNAME}":"​\/​dev", ​                       "​{#​FSTYPE}":"​devtmpfs"​ }, 
-    { "​{#​FSNAME}":"​\/​dev\/​pts", ​                  "​{#​FSTYPE}":"​devpts" ​  }, 
-    { "​{#​FSNAME}":"​\/", ​                          "​{#​FSTYPE}":"​ext3" ​    }, 
-    { "​{#​FSNAME}":"​\/​lib\/​init\/​rw", ​             "​{#​FSTYPE}":"​tmpfs" ​   }, 
-    { "​{#​FSNAME}":"​\/​dev\/​shm", ​                  "​{#​FSTYPE}":"​tmpfs" ​   }, 
-    { "​{#​FSNAME}":"​\/​home", ​                      "​{#​FSTYPE}":"​ext3" ​    }, 
-    { "​{#​FSNAME}":"​\/​tmp", ​                       "​{#​FSTYPE}":"​ext3" ​    }, 
-    { "​{#​FSNAME}":"​\/​usr", ​                       "​{#​FSTYPE}":"​ext3" ​    }, 
-    { "​{#​FSNAME}":"​\/​var", ​                       "​{#​FSTYPE}":"​ext3" ​    }, 
-    { "​{#​FSNAME}":"​\/​sys\/​fs\/​fuse\/​connections",​ "​{#​FSTYPE}":"​fusectl" ​ } 
-    ​ 
-    ] 
-  } 
- 
-Then, in the discovery rule's "​Filter"​ field, we could specify "​{#​FSTYPE}"​ as a macro and "​rootfs|ext3"​ as a regular expression. 
- 
-<​note>​You don't have to use macro names FSNAME/​FSTYPE with custom LLD rules, you are free to use whatever names you like.</​note>​