# Icinga 2 Features <a id="icinga2-features"></a>

## Logging <a id="logging"></a>

Icinga 2 supports three different types of logging:

* File logging
* Syslog (on Linux/UNIX)
* Console logging (`STDOUT` on tty)

You can enable additional loggers using the `icinga2 feature enable`
and `icinga2 feature disable` commands to configure loggers:

Feature  | Description
---------|------------
debuglog | Debug log (path: `/var/log/icinga2/debug.log`, severity: `debug` or higher)
mainlog  | Main log (path: `/var/log/icinga2/icinga2.log`, severity: `information` or higher)
syslog   | Syslog (severity: `warning` or higher)

By default file the `mainlog` feature is enabled. When running Icinga 2
on a terminal log messages with severity `information` or higher are
written to the console.

### Log Rotation <a id="logging-logrotate"></a>

Packages provide a configuration file for [logrotate](https://linux.die.net/man/8/logrotate)
on Linux/Unix. Typically this is installed into `/etc/logrotate.d/icinga2`
and modifications won't be overridden on upgrade.

Instead of sending the reload HUP signal, logrotate
sends the USR1 signal to notify the Icinga daemon
that it has rotate the log file. Icinga reopens the log
files then:

* `/var/log/icinga2/icinga2.log` (requires `mainlog` enabled)
* `/var/log/icinga2/debug.log` (requires `debuglog` enabled)
* `/var/log/icinga2/erorr.log`

By default, log files will be rotated daily.

## Core Backends <a id="core-backends"></a>

### REST API <a id="core-backends-api"></a>

The REST API is documented [here](12-icinga2-api.md#icinga2-api) as a core feature.

### IDO Database (DB IDO) <a id="db-ido"></a>

The IDO (Icinga Data Output) feature for Icinga 2 takes care of exporting all
configuration and status information into a database. The IDO database is used
by Icinga Web 2 as data backend.

Details on the installation can be found in the [Configuring DB IDO](02-getting-started.md#configuring-db-ido-mysql)
chapter. Details on the configuration can be found in the
[IdoMysqlConnection](09-object-types.md#objecttype-idomysqlconnection) and
[IdoPgsqlConnection](09-object-types.md#objecttype-idopgsqlconnection)
object configuration documentation.

#### DB IDO Health <a id="db-ido-health"></a>

If the monitoring health indicator is critical in Icinga Web 2,
you can use the following queries to manually check whether Icinga 2
is actually updating the IDO database.

Icinga 2 writes its current status to the `icinga_programstatus` table
every 10 seconds. The query below checks 60 seconds into the past which is a reasonable
amount of time -- adjust it for your requirements. If the condition is not met,
the query returns an empty result.

> **Tip**
>
> Use [check plugins](05-service-monitoring.md#service-monitoring-plugins) to monitor the backend.

Replace the `default` string with your instance name if different.

Example for MySQL:

```
# mysql -u root -p icinga -e "SELECT status_update_time FROM icinga_programstatus ps
  JOIN icinga_instances i ON ps.instance_id=i.instance_id
  WHERE (UNIX_TIMESTAMP(ps.status_update_time) > UNIX_TIMESTAMP(NOW())-60)
  AND i.instance_name='default';"

+---------------------+
| status_update_time  |
+---------------------+
| 2014-05-29 14:29:56 |
+---------------------+
```

Example for PostgreSQL:

```
# export PGPASSWORD=icinga; psql -U icinga -d icinga -c "SELECT ps.status_update_time FROM icinga_programstatus AS ps
  JOIN icinga_instances AS i ON ps.instance_id=i.instance_id
  WHERE ((SELECT extract(epoch from status_update_time) FROM icinga_programstatus) > (SELECT extract(epoch from now())-60))
  AND i.instance_name='default'";

status_update_time
------------------------
 2014-05-29 15:11:38+02
(1 Zeile)
```

A detailed list on the available table attributes can be found in the [DB IDO Schema documentation](24-appendix.md#schema-db-ido).

#### DB IDO in Cluster HA Zones <a id="db-ido-cluster-ha"></a>

The DB IDO feature supports [High Availability](06-distributed-monitoring.md#distributed-monitoring-high-availability-db-ido) in
the Icinga 2 cluster.

By default, both endpoints in a zone calculate the
endpoint which activates the feature, the other endpoint
automatically pauses it. If the cluster connection
breaks at some point, the paused IDO feature automatically
does a failover.

You can disable this behaviour by setting `enable_ha = false`
in both feature configuration files.

#### DB IDO Cleanup <a id="db-ido-cleanup"></a>

Objects get deactivated when they are deleted from the configuration.
This is visible with the `is_active` column in the `icinga_objects` table.
Therefore all queries need to join this table and add `WHERE is_active=1` as
condition. Deleted objects preserve their history table entries for later SLA
reporting.

Historical data isn't purged by default. You can enable the least
kept data age inside the `cleanup` configuration attribute for the
IDO features [IdoMysqlConnection](09-object-types.md#objecttype-idomysqlconnection)
and [IdoPgsqlConnection](09-object-types.md#objecttype-idopgsqlconnection).

Example if you prefer to keep notification history for 30 days:

```
  cleanup = {
     notifications_age = 30d
     contactnotifications_age = 30d
  }
```

The historical tables are populated depending on the data `categories` specified.
Some tables are empty by default.

#### DB IDO Tuning <a id="db-ido-tuning"></a>

As with any application database, there are ways to optimize and tune the database performance.

General tips for performance tuning:

* [MariaDB KB](https://mariadb.com/kb/en/library/optimization-and-tuning/)
* [PostgreSQL Wiki](https://wiki.postgresql.org/wiki/Performance_Optimization)

Re-creation of indexes, changed column values, etc. will increase the database size. Ensure to
add health checks for this, and monitor the trend in your Grafana dashboards.

In order to optimize the tables, there are different approaches. Always keep in mind to have a
current backup and schedule maintenance downtime for these kind of tasks!

MySQL:

```
mariadb> OPTIMIZE TABLE icinga_statehistory;
```

> **Important**
>
> Tables might not support optimization at runtime. This can take a **long** time.
>
> `Table does not support optimize, doing recreate + analyze instead`.

If you want to optimize all tables in a specified database, there is a script called `mysqlcheck`.
This also allows to repair broken tables in the case of emergency.

```
mysqlcheck --optimize icinga
```

PostgreSQL:

```
icinga=# vacuum;
VACUUM
```

> **Note**
>
> Don't use `VACUUM FULL` as this has a severe impact on performance.


## Metrics <a id="metrics"></a>

Whenever a host or service check is executed, or received via the REST API,
best practice is to provide performance data.

This data is parsed by features sending metrics to time series databases (TSDB):

* [Graphite](14-features.md#graphite-carbon-cache-writer)
* [InfluxDB](14-features.md#influxdb-writer)
* [OpenTSDB](14-features.md#opentsdb-writer)

Metrics, state changes and notifications can be managed with the following integrations:

* [Elastic Stack](14-features.md#elastic-stack-integration)
* [Graylog](14-features.md#graylog-integration)


### Graphite Writer <a id="graphite-carbon-cache-writer"></a>

[Graphite](13-addons.md#addons-graphing-graphite) is a tool stack for storing
metrics and needs to be running prior to enabling the `graphite` feature.

Icinga 2 writes parsed metrics directly to Graphite's Carbon Cache
TCP port, defaulting to `2003`.

You can enable the feature using

```
# icinga2 feature enable graphite
```

By default the [GraphiteWriter](09-object-types.md#objecttype-graphitewriter) feature
expects the Graphite Carbon Cache to listen at `127.0.0.1` on TCP port `2003`.

#### Graphite Schema <a id="graphite-carbon-cache-writer-schema"></a>

The current naming schema is defined as follows. The [Icinga Web 2 Graphite module](https://github.com/icinga/icingaweb2-module-graphite)
depends on this schema.

The default prefix for hosts and services is configured using
[runtime macros](03-monitoring-basics.md#runtime-macros)like this:

```
icinga2.$host.name$.host.$host.check_command$
icinga2.$host.name$.services.$service.name$.$service.check_command$
```

You can customize the prefix name by using the `host_name_template` and
`service_name_template` configuration attributes.

The additional levels will allow fine granular filters and also template
capabilities, e.g. by using the check command `disk` for specific
graph templates in web applications rendering the Graphite data.

The following characters are escaped in prefix labels:

  Character	| Escaped character
  --------------|--------------------------
  whitespace	| _
  .		| _
  \		| _
  /		| _

Metric values are stored like this:

```
<prefix>.perfdata.<perfdata-label>.value
```

The following characters are escaped in performance labels
parsed from plugin output:

  Character	| Escaped character
  --------------|--------------------------
  whitespace	| _
  \		| _
  /		| _
  ::		| .

Note that labels may contain dots (`.`) allowing to
add more subsequent levels inside the Graphite tree.
`::` adds support for [multi performance labels](http://my-plugin.de/wiki/projects/check_multi/configuration/performance)
and is therefore replaced by `.`.

By enabling `enable_send_thresholds` Icinga 2 automatically adds the following threshold metrics:

```
<prefix>.perfdata.<perfdata-label>.min
<prefix>.perfdata.<perfdata-label>.max
<prefix>.perfdata.<perfdata-label>.warn
<prefix>.perfdata.<perfdata-label>.crit
```

By enabling `enable_send_metadata` Icinga 2 automatically adds the following metadata metrics:

```
<prefix>.metadata.current_attempt
<prefix>.metadata.downtime_depth
<prefix>.metadata.acknowledgement
<prefix>.metadata.execution_time
<prefix>.metadata.latency
<prefix>.metadata.max_check_attempts
<prefix>.metadata.reachable
<prefix>.metadata.state
<prefix>.metadata.state_type
```

Metadata metric overview:

  metric             | description
  -------------------|------------------------------------------
  current_attempt    | current check attempt
  max_check_attempts | maximum check attempts until the hard state is reached
  reachable          | checked object is reachable
  downtime_depth     | number of downtimes this object is in
  acknowledgement    | whether the object is acknowledged or not
  execution_time     | check execution time
  latency            | check latency
  state              | current state of the checked object
  state_type         | 0=SOFT, 1=HARD state

The following example illustrates how to configure the storage schemas for Graphite Carbon
Cache.

```
[icinga2_default]
# intervals like PNP4Nagios uses them per default
pattern = ^icinga2\.
retentions = 1m:2d,5m:10d,30m:90d,360m:4y
```

### InfluxDB Writer <a id="influxdb-writer"></a>

Once there are new metrics available, Icinga 2 will directly write them to the
defined InfluxDB HTTP API.

You can enable the feature using

```
# icinga2 feature enable influxdb
```

By default the [InfluxdbWriter](09-object-types.md#objecttype-influxdbwriter) feature
expects the InfluxDB daemon to listen at `127.0.0.1` on port `8086`.

Measurement names and tags are fully configurable by the end user. The InfluxdbWriter
object will automatically add a `metric` tag to each data point. This correlates to the
perfdata label. Fields (value, warn, crit, min, max, unit) are created from data if available
and the configuration allows it.  If a value associated with a tag is not able to be
resolved, it will be dropped and not sent to the target host.

Backslashes are allowed in tag keys, tag values and field keys, however they are also
escape characters when followed by a space or comma, but cannot be escaped themselves.
As a result all trailling slashes in these fields are replaced with an underscore.  This
predominantly affects Windows paths e.g. `C:\` becomes `C:_`.

The database is assumed to exist so this object will make no attempt to create it currently.

If [SELinux](22-selinux.md#selinux) is enabled, it will not allow access for Icinga 2 to InfluxDB until the [boolean](22-selinux.md#selinux-policy-booleans)
`icinga2_can_connect_all` is set to true as InfluxDB is not providing its own policy.

More configuration details can be found [here](09-object-types.md#objecttype-influxdbwriter).

#### Instance Tagging <a id="influxdb-writer-instance-tags"></a>

Consider the following service check:

```
apply Service "disk" for (disk => attributes in host.vars.disks) {
  import "generic-service"
  check_command = "disk"
  display_name = "Disk " + disk
  vars.disk_partitions = disk
  assign where host.vars.disks
}
```

This is a typical pattern for checking individual disks, NICs, SSL certificates etc associated
with a host.  What would be useful is to have the data points tagged with the specific instance
for that check.  This would allow you to query time series data for a check on a host and for a
specific instance e.g. /dev/sda.  To do this quite simply add the instance to the service variables:

```
apply Service "disk" for (disk => attributes in host.vars.disks) {
  ...
  vars.instance = disk
  ...
}
```

Then modify your writer configuration to add this tag to your data points if the instance variable
is associated with the service:

```
object InfluxdbWriter "influxdb" {
  ...
  service_template = {
    measurement = "$service.check_command$"
    tags = {
      hostname = "$host.name$"
      service = "$service.name$"
      instance = "$service.vars.instance$"
    }
  }
  ...
}
```

### Elastic Stack Integration <a id="elastic-stack-integration"></a>

[Icingabeat](https://github.com/icinga/icingabeat) is an Elastic Beat that fetches data
from the Icinga 2 API and sends it either directly to [Elasticsearch](https://www.elastic.co/products/elasticsearch)
or [Logstash](https://www.elastic.co/products/logstash).

More integrations:

* [Logstash output](https://github.com/Icinga/logstash-output-icinga) for the Icinga 2 API.
* [Logstash Grok Pattern](https://github.com/Icinga/logstash-grok-pattern) for Icinga 2 logs.

#### Elasticsearch Writer <a id="elasticsearch-writer"></a>

This feature forwards check results, state changes and notification events
to an [Elasticsearch](https://www.elastic.co/products/elasticsearch) installation over its HTTP API.

The check results include parsed performance data metrics if enabled.

> **Note**
>
> Elasticsearch 5.x or 6.x are required. This feature has been successfully tested with
> Elasticsearch 5.6.7 and 6.3.1.



Enable the feature and restart Icinga 2.

```
# icinga2 feature enable elasticsearch
```

The default configuration expects an Elasticsearch instance running on `localhost` on port `9200
 and writes to an index called `icinga2`.

More configuration details can be found [here](09-object-types.md#objecttype-elasticsearchwriter).

#### Current Elasticsearch Schema <a id="elastic-writer-schema"></a>

The following event types are written to Elasticsearch:

* icinga2.event.checkresult
* icinga2.event.statechange
* icinga2.event.notification

Performance data metrics must be explicitly enabled with the `enable_send_perfdata`
attribute.

Metric values are stored like this:

```
check_result.perfdata.<perfdata-label>.value
```

The following characters are escaped in perfdata labels:

  Character   | Escaped character
  ------------|--------------------------
  whitespace  | _
  \           | _
  /           | _
  ::          | .

Note that perfdata labels may contain dots (`.`) allowing to
add more subsequent levels inside the tree.
`::` adds support for [multi performance labels](http://my-plugin.de/wiki/projects/check_multi/configuration/performance)
and is therefore replaced by `.`.

Icinga 2 automatically adds the following threshold metrics
if existing:

```
check_result.perfdata.<perfdata-label>.min
check_result.perfdata.<perfdata-label>.max
check_result.perfdata.<perfdata-label>.warn
check_result.perfdata.<perfdata-label>.crit
```


### Graylog Integration <a id="graylog-integration"></a>

#### GELF Writer <a id="gelfwriter"></a>

The `Graylog Extended Log Format` (short: [GELF](http://docs.graylog.org/en/latest/pages/gelf.html))
can be used to send application logs directly to a TCP socket.

While it has been specified by the [Graylog](https://www.graylog.org) project as their
[input resource standard](http://docs.graylog.org/en/latest/pages/sending_data.html), other tools such as
[Logstash](https://www.elastic.co/products/logstash) also support `GELF` as
[input type](https://www.elastic.co/guide/en/logstash/current/plugins-inputs-gelf.html).

You can enable the feature using

```
# icinga2 feature enable gelf
```

By default the `GelfWriter` object expects the GELF receiver to listen at `127.0.0.1` on TCP port `12201`.
The default `source`  attribute is set to `icinga2`. You can customize that for your needs if required.

Currently these events are processed:
* Check results
* State changes
* Notifications


### OpenTSDB Writer <a id="opentsdb-writer"></a>

While there are some OpenTSDB collector scripts and daemons like tcollector available for
Icinga 1.x it's more reasonable to directly process the check and plugin performance
in memory in Icinga 2. Once there are new metrics available, Icinga 2 will directly
write them to the defined TSDB TCP socket.

You can enable the feature using

```
# icinga2 feature enable opentsdb
```

By default the `OpenTsdbWriter` object expects the TSD to listen at
`127.0.0.1` on port `4242`.

The current naming schema is

```
icinga.host.<metricname>
icinga.service.<servicename>.<metricname>
```

for host and service checks. The tag host is always applied.

To make sure Icinga 2 writes a valid metric into OpenTSDB some characters are replaced
with `_` in the target name:

```
\  (and space)
```

The resulting name in OpenTSDB might look like:

```
www-01 / http-cert / response time
icinga.http_cert.response_time
```

In addition to the performance data retrieved from the check plugin, Icinga 2 sends
internal check statistic data to OpenTSDB:

  metric             | description
  -------------------|------------------------------------------
  current_attempt    | current check attempt
  max_check_attempts | maximum check attempts until the hard state is reached
  reachable          | checked object is reachable
  downtime_depth     | number of downtimes this object is in
  acknowledgement    | whether the object is acknowledged or not
  execution_time     | check execution time
  latency            | check latency
  state              | current state of the checked object
  state_type         | 0=SOFT, 1=HARD state

While reachable, state and state_type are metrics for the host or service the
other metrics follow the current naming schema

```
icinga.check.<metricname>
```

with the following tags

  tag     | description
  --------|------------------------------------------
  type    | the check type, one of [host, service]
  host    | hostname, the check ran on
  service | the service name (if type=service)

> **Note**
>
> You might want to set the tsd.core.auto_create_metrics setting to `true`
> in your opentsdb.conf configuration file.


### Writing Performance Data Files <a id="writing-performance-data-files"></a>

PNP and Graphios use performance data collector daemons to fetch
the current performance files for their backend updates.

Therefore the Icinga 2 [PerfdataWriter](09-object-types.md#objecttype-perfdatawriter)
feature allows you to define the output template format for host and services helped
with Icinga 2 runtime vars.

```
host_format_template = "DATATYPE::HOSTPERFDATA\tTIMET::$icinga.timet$\tHOSTNAME::$host.name$\tHOSTPERFDATA::$host.perfdata$\tHOSTCHECKCOMMAND::$host.check_command$\tHOSTSTATE::$host.state$\tHOSTSTATETYPE::$host.state_type$"
service_format_template = "DATATYPE::SERVICEPERFDATA\tTIMET::$icinga.timet$\tHOSTNAME::$host.name$\tSERVICEDESC::$service.name$\tSERVICEPERFDATA::$service.perfdata$\tSERVICECHECKCOMMAND::$service.check_command$\tHOSTSTATE::$host.state$\tHOSTSTATETYPE::$host.state_type$\tSERVICESTATE::$service.state$\tSERVICESTATETYPE::$service.state_type$"
```

The default templates are already provided with the Icinga 2 feature configuration
which can be enabled using

```
# icinga2 feature enable perfdata
```

By default all performance data files are rotated in a 15 seconds interval into
the `/var/spool/icinga2/perfdata/` directory as `host-perfdata.<timestamp>` and
`service-perfdata.<timestamp>`.
External collectors need to parse the rotated performance data files and then
remove the processed files.



## Livestatus <a id="setting-up-livestatus"></a>

The [MK Livestatus](https://mathias-kettner.de/checkmk_livestatus.html) project
implements a query protocol that lets users query their Icinga instance for
status information. It can also be used to send commands.

The Livestatus component that is distributed as part of Icinga 2 is a
re-implementation of the Livestatus protocol which is compatible with MK
Livestatus.

> **Tip**
>
> Only install the Livestatus feature if your web interface or addon requires
> you to do so.
> [Icinga Web 2](02-getting-started.md#setting-up-icingaweb2) does not need
> Livestatus.

Details on the available tables and attributes with Icinga 2 can be found
in the [Livestatus Schema](24-appendix.md#schema-livestatus) section.

You can enable Livestatus using icinga2 feature enable:

```
# icinga2 feature enable livestatus
```

After that you will have to restart Icinga 2:

```
# systemctl restart icinga2
```

By default the Livestatus socket is available in `/var/run/icinga2/cmd/livestatus`.

In order for queries and commands to work you will need to add your query user
(e.g. your web server) to the `icingacmd` group:

```
# usermod -a -G icingacmd www-data
```

The Debian packages use `nagios` as the user and group name. Make sure to change `icingacmd` to
`nagios` if you're using Debian.

Change `www-data` to the user you're using to run queries.

In order to use the historical tables provided by the livestatus feature (for example, the
`log` table) you need to have the `CompatLogger` feature enabled. By default these logs
are expected to be in `/var/log/icinga2/compat`. A different path can be set using the
`compat_log_path` configuration attribute.

```
# icinga2 feature enable compatlog
```

### Livestatus Sockets <a id="livestatus-sockets"></a>

Other to the Icinga 1.x Addon, Icinga 2 supports two socket types

* Unix socket (default)
* TCP socket

Details on the configuration can be found in the [LivestatusListener](09-object-types.md#objecttype-livestatuslistener)
object configuration.

### Livestatus GET Queries <a id="livestatus-get-queries"></a>

> **Note**
>
> All Livestatus queries require an additional empty line as query end identifier.
> The `nc` tool (`netcat`) provides the `-U` parameter to communicate using
> a unix socket.

There also is a Perl module available in CPAN for accessing the Livestatus socket
programmatically: [Monitoring::Livestatus](http://search.cpan.org/~nierlein/Monitoring-Livestatus-0.74/)


Example using the unix socket:

```
# echo -e "GET services\n" | /usr/bin/nc -U /var/run/icinga2/cmd/livestatus

Example using the tcp socket listening on port `6558`:

# echo -e 'GET services\n' | netcat 127.0.0.1 6558

# cat servicegroups <<EOF
GET servicegroups

EOF

(cat servicegroups; sleep 1) | netcat 127.0.0.1 6558
```

### Livestatus COMMAND Queries <a id="livestatus-command-queries"></a>

A list of available external commands and their parameters can be found [here](24-appendix.md#external-commands-list-detail)

```
$ echo -e 'COMMAND <externalcommandstring>' | netcat 127.0.0.1 6558
```

### Livestatus Filters <a id="livestatus-filters"></a>

and, or, negate

  Operator  | Negate   | Description
  ----------|----------|-------------
   =        | !=       | Equality
   ~        | !~       | Regex match
   =~       | !=~      | Equality ignoring case
   ~~       | !~~      | Regex ignoring case
   <        |          | Less than
   >        |          | Greater than
   <=       |          | Less than or equal
   >=       |          | Greater than or equal


### Livestatus Stats <a id="livestatus-stats"></a>

Schema: "Stats: aggregatefunction aggregateattribute"

  Aggregate Function | Description
  -------------------|--------------
  sum                | &nbsp;
  min                | &nbsp;
  max                | &nbsp;
  avg                | sum / count
  std                | standard deviation
  suminv             | sum (1 / value)
  avginv             | suminv / count
  count              | ordinary default for any stats query if not aggregate function defined

Example:

```
GET hosts
Filter: has_been_checked = 1
Filter: check_type = 0
Stats: sum execution_time
Stats: sum latency
Stats: sum percent_state_change
Stats: min execution_time
Stats: min latency
Stats: min percent_state_change
Stats: max execution_time
Stats: max latency
Stats: max percent_state_change
OutputFormat: json
ResponseHeader: fixed16
```

### Livestatus Output <a id="livestatus-output"></a>

* CSV

CSV output uses two levels of array separators: The members array separator
is a comma (1st level) while extra info and host|service relation separator
is a pipe (2nd level).

Separators can be set using ASCII codes like:

```
Separators: 10 59 44 124
```

* JSON

Default separators.

### Livestatus Error Codes <a id="livestatus-error-codes"></a>

  Code      | Description
  ----------|--------------
  200       | OK
  404       | Table does not exist
  452       | Exception on query

### Livestatus Tables <a id="livestatus-tables"></a>

  Table         | Join      |Description
  --------------|-----------|----------------------------
  hosts         | &nbsp;    | host config and status attributes, services counter
  hostgroups    | &nbsp;    | hostgroup config, status attributes and host/service counters
  services      | hosts     | service config and status attributes
  servicegroups | &nbsp;    | servicegroup config, status attributes and service counters
  contacts      | &nbsp;    | contact config and status attributes
  contactgroups | &nbsp;    | contact config, members
  commands      | &nbsp;    | command name and line
  status        | &nbsp;    | programstatus, config and stats
  comments      | services  | status attributes
  downtimes     | services  | status attributes
  timeperiods   | &nbsp;    | name and is inside flag
  endpoints     | &nbsp;    | config and status attributes
  log           | services, hosts, contacts, commands | parses [compatlog](09-object-types.md#objecttype-compatlogger) and shows log attributes
  statehist     | hosts, services | parses [compatlog](09-object-types.md#objecttype-compatlogger) and aggregates state change attributes
  hostsbygroup  | hostgroups | host attributes grouped by hostgroup and its attributes
  servicesbygroup | servicegroups | service attributes grouped by servicegroup and its attributes
  servicesbyhostgroup  | hostgroups | service attributes grouped by hostgroup and its attributes

The `commands` table is populated with `CheckCommand`, `EventCommand` and `NotificationCommand` objects.

A detailed list on the available table attributes can be found in the [Livestatus Schema documentation](24-appendix.md#schema-livestatus).


## Deprecated Features <a id="deprecated-features"></a>

### Status Data Files <a id="status-data"></a>

> **Note**
>
> This feature is DEPRECATED and will be removed in Icinga 2 v2.11.

Icinga 1.x writes object configuration data and status data in a cyclic
interval to its `objects.cache` and `status.dat` files. Icinga 2 provides
the `StatusDataWriter` object which dumps all configuration objects and
status updates in a regular interval.

```
# icinga2 feature enable statusdata
```

If you are not using any web interface or addon which uses these files,
you can safely disable this feature.

### Compat Log Files <a id="compat-logging"></a>

> **Note**
>
> This feature is DEPRECATED and will be removed in Icinga 2 v2.11.

The Icinga 1.x log format is considered being the `Compat Log`
in Icinga 2 provided with the `CompatLogger` object.

These logs are used for informational representation in
external web interfaces parsing the logs, but also to generate
SLA reports and trends.
The [Livestatus](14-features.md#setting-up-livestatus) feature uses these logs
for answering queries to historical tables.

The `CompatLogger` object can be enabled with

```
# icinga2 feature enable compatlog
```

By default, the Icinga 1.x log file called `icinga.log` is located
in `/var/log/icinga2/compat`. Rotated log files are moved into
`var/log/icinga2/compat/archives`.

### External Command Pipe <a id="external-commands"></a>

> **Note**
>
> Please use the [REST API](12-icinga2-api.md#icinga2-api) as modern and secure alternative
> for external actions.

> **Note**
>
> This feature is DEPRECATED with 2.11 and will be removed in future releases.
> Check the [roadmap](https://github.com/Icinga/icinga2/milestones).

Icinga 2 provides an external command pipe for processing commands
triggering specific actions (for example rescheduling a service check
through the web interface).

In order to enable the `ExternalCommandListener` configuration use the
following command and restart Icinga 2 afterwards:

```
# icinga2 feature enable command
```

Icinga 2 creates the command pipe file as `/var/run/icinga2/cmd/icinga2.cmd`
using the default configuration.

Web interfaces and other Icinga addons are able to send commands to
Icinga 2 through the external command pipe, for example for rescheduling
a forced service check:

```
# /bin/echo "[`date +%s`] SCHEDULE_FORCED_SVC_CHECK;localhost;ping4;`date +%s`" >> /var/run/icinga2/cmd/icinga2.cmd

# tail -f /var/log/messages

Oct 17 15:01:25 icinga-server icinga2: Executing external command: [1382014885] SCHEDULE_FORCED_SVC_CHECK;localhost;ping4;1382014885
Oct 17 15:01:25 icinga-server icinga2: Rescheduling next check for service 'ping4'
```

A list of currently supported external commands can be found [here](24-appendix.md#external-commands-list-detail).

Detailed information on the commands and their required parameters can be found
on the [Icinga 1.x documentation](https://docs.icinga.com/latest/en/extcommands2.html).


### Check Result Files <a id="check-result-files"></a>

> **Note**
>
> This feature is DEPRECATED and will be removed in Icinga 2 v2.11.

Icinga 1.x writes its check result files to a temporary spool directory
where they are processed in a regular interval.
While this is extremely inefficient in performance regards it has been
rendered useful for passing passive check results directly into Icinga 1.x
skipping the external command pipe.

Several clustered/distributed environments and check-aggregation addons
use that method. In order to support step-by-step migration of these
environments, Icinga 2 supports the `CheckResultReader` object.

There is no feature configuration available, but it must be defined
on-demand in your Icinga 2 objects configuration.

```
object CheckResultReader "reader" {
  spool_dir = "/data/check-results"
}
```
