LMD fetches Livestatus data from one or multiple sources and provides:

• A combined Livestatus API for those sources.
• A cache which makes Livestatus queries a lot faster than requesting them directly from the remote sources.
• A enhanced Livestatus API with more useful output formats and sorting. See list below.
• Aggregated Livestatus results for multiple backends.
• A Prometheus exporter for Livestatus based metrics for Nagios, Icinga, Shinken and Naemon.

So basically this is a "Livestatus In / Livestatus Out" daemon. Its main purpose is to provide the backend handling of the Thruk Monitoring Gui in a native compiled fast daemon, but it should work for everything which requires Livestatus.

Log table requests and commands are just passed through to the actual backends.

You will need

• Go >= 1.10

to compile lmd.

After starting LMD, it fetches all tables via Livestatus API from all configured remote backends. It then polls periodically all dynamic parts of the objects, like host status, plugin output or downtime status.

When there are no incoming connections to LMD, it switches into the idle mode with a slower poll interval. As soon as the first client requests some data, LMD will do a spin up and run a synchronous update (with small timeout) and change back to the normal poll interval.

If you want to use LMD with Thruk within OMD, see the omd/lmd page for a quick start. The OMD-Labs Edition is already prepared to use LMD.

    %> go get -u github.com/sni/lmd/lmd

Copy lmd.ini.example to lmd.ini and change to your needs. Then run lmd. You can specify the path to your config file with --config.

    lmd --config=/etc/lmd/lmd.ini

The configuration is explained in the lmd.ini.example in detail. There are several different connection types.

Remote Livestatus connections via tcp can be defined as:

    [[Connections]]
    name   = "Monitoring Site A"
    id     = "id1"
    source = ["192.168.33.10:6557"]

If the source is a cluster, you can specify multiple addresses like

    source = ["192.168.33.10:6557", "192.168.33.20:6557"]

Local unix sockets Livestatus connections can be defined as:

    [[Connections]]
    name   = "Monitoring Site A"
    id     = "id1"
    source = ["/var/tmp/nagios/live.sock"]

It is possible to operate LMD in a cluster mode which means multiple LMDs connect to a network and share the resources. All backend connections will be split up and divided upon all cluster nodes. Incoming requests will be forwared and merged.

In order to setup cluster operations, you need to add a http(s) listener and a list of nodes. All nodes should share the same configuration file.

Listen  = ["/var/tmp/lmd.sock", "http://*:8080"]
Nodes   = ["http://10.0.0.1:8080", "http://10.0.0.2:8080"]

There are some new/changed Livestatus query headers:

The default OutputFormat is wrapped_json but json is also supported.

The wrapped_json format will put the normal json result in a hash with some more extra meta data:

- columns: the column names (if requested)
- data: the original result.
- total_count: the number of matches in the result set _before_ the limit and offset applied.
- failed: a hash of backends which have errored for some reason.

The only ResponseHeader supported right now is fixed16.

There is a new Backends header which may set a space separated list of backends. If none specific, all are returned.

ex.:

Backends: id1 id2

The offset header can be used to only retrieve a subset of the complete result set. Best used together with the sort header.

Offset: 100
Limit: 10

This will return entrys 100-109 from the overal result set.

The sort header can be used to sort the results by one or more columns. Multiple sort header can be used.

Sort: <column name> <asc/desc>

Sorting by custom variables is possible like this:

Sort: custom_variables <name> <asc/desc>

ex.:

GET hosts
Sort: state asc
Sort: name desc
Sort: custom_variables WORKER asc

• peer_key: id of the backend where this object belongs too (all tables)
• peer_name: name of the backend where this object belongs too (all tables)
• has_long_plugin_output: flag if there is long_plugin_output or not (hosts/services table)

The improved performance comes at a price of course. The following numbers should give you a rough idea on what to expect: An example installation with 200.000 services at a 3 second update interval uses around 1.5gB of memory and 200kByte/s of bandwith. This makes an average of 7kB memory and 1Byte/s of bandwitdh usage per service.

However your milage may vary, these number heavily depend on the size of the plugin output and the check interval of your services. Use the Prometheus exporter to create nice graphs to see how your environment differs.

Btw, changing the update interval to 30 seconds does not reduce the used bandwith, you just have to update many services every 30 seconds than small packages every 3 seconds.

Some ideas may or may not be implemented in the future

• Add transparent and half-transparent mode which just handles the map/reduce without cache. This is implemented for log table and commands anyway already. Just requires an additional header.
• Cache last 24h of logfiles to speed up most logfile requests
• Fix updating comments (takes too long after sending commands)
• Make use of lmd_last_cache_update in federation mode
• deduplicate large stringlists like contacts, maybe hostgroups and servicegroups