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6 Reglas LLD personalizadas
Descripción general
También es posible crear una regla LLD completamente personalizada, descubriendo cualquier tipo de entidades, por ejemplo, bases de datos en un servidor de bases de datos.
Para hacerlo, se debe crear una métrica personalizada que devuelva JSON, especificando objetos encontrados y, opcionalmente, algunas propiedades de los mismos. La cantidad de macros por entidad no están limitadas, mientras que las reglas de descubrimiento integradas devuelven una o dos macros (por ejemplo, dos para el descubrimiento del sistema de archivos ), es posible devolver más.
Example
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":
#!/usr/bin/perl
$first = 1;
print "[\n";
for (`cat /proc/mounts`)
{
($fsname, $fstype) = m/\S+ (\S+) (\S+)/;
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";Allowed symbols for LLD macro names are 0-9 , A-Z , _ , . Lowercase letters are not supported in the names.
An example of its output (reformatted for clarity) is shown below. JSON for custom discovery checks has to follow the same format.
[
{ "{#FSNAME}":"/", "{#FSTYPE}":"rootfs" },
{ "{#FSNAME}":"/sys", "{#FSTYPE}":"sysfs" },
{ "{#FSNAME}":"/proc", "{#FSTYPE}":"proc" },
{ "{#FSNAME}":"/dev", "{#FSTYPE}":"devtmpfs" },
{ "{#FSNAME}":"/dev/pts", "{#FSTYPE}":"devpts" },
{ "{#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" }
]In the previous example it is required that the keys match the LLD macro names used in prototypes, the alternative is to extract LLD macro values using JSONPath {#FSNAME} → $.fsname and {#FSTYPE} → $.fstype, thus making such script possible:
#!/usr/bin/perl
$first = 1;
print "[\n";
for (`cat /proc/mounts`)
{
($fsname, $fstype) = m/\S+ (\S+) (\S+)/;
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";An example of its output (reformatted for clarity) is shown below. JSON for custom discovery checks has to follow the same format.
[
{ "fsname":"/", "fstype":"rootfs" },
{ "fsname":"/sys", "fstype":"sysfs" },
{ "fsname":"/proc", "fstype":"proc" },
{ "fsname":"/dev", "fstype":"devtmpfs" },
{ "fsname":"/dev/pts", "fstype":"devpts" },
{ "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.
You don't have to use macro names FSNAME/FSTYPE with custom LLD rules, you are free to use whatever names you like. In case JSONPath is used then LLD row will be an array element that can be an object, but it can be also another array or a value.
Note that, if using a user parameter, the return value is limited to 512 KB. For more details, see data limits for LLD return values.