# Templates 

A template defines what kind of data a graph visualizes, which kind of graph to
use and its style. Essentially the Icinga Web Graphite Integration is using
templates to tell Graphite how to render which graphs.

* [Location](04-Templates.md#templates-location)
* [Structure](04-Templates.md#templates-structure)
    * [graph](04-Templates.md#templates-structure-graph)
    * [metric_filters](04-Templates.md#templates-structure-metric-filters)
    * [urlparams](04-Templates.md#templates-structure-urlparams)
    * [functions](04-Templates.md#templates-structure-functions)
* [Example](04-Templates.md#templates-example)
* [Default Template Settings](04-Templates.md#templates-default-settings)

## Template Location 

There are a bunch of templates already included, located in
the installation path. (e.g. `/usr/share/icingaweb2/modules/graphite`)

To add additional/customized templates, place them in its configuration path.
(e.g. `/etc/icingaweb2/modules/graphite/templates`) These will either extend
the available templates or override some of them. Subfolders placed here will
also be included in the same way, while additionally extending or overriding
templates of its parent folders.

> **Note:**
>
> Hidden files and directories (with a leading dot) are ignored.

## Template Structure 

Templates are organized within simple INI files. However, it is perfectly valid
to define multiple templates in a single file.

The name of a section consists of two parts separated by a dot:

    [hostalive-rta.graph]

The first part is the name of the template and the second part the name of one
of the following configuration topics:

> **Note:**
>
> Template file will be ignored if the [graph] or [metric_filters] section is missing.

### Template Structure: graph 

Supports a single option called `check_command` and should be set to the name
of a Icinga 2 [check-command](https://www.icinga.com/docs/icinga2/latest/doc/03-monitoring-basics/#check-commands).
To get multiple graphs for hosts and services with this check-command, multiple
templates can reference the same check-command.

If multiple check commands do effectively the same thing and yield the same
perfdata, all of them may be specified separated by comma. E.g.:

```ini
[ping-rta.graph]
check_command = "ping, ping4, ping6"
```

### Template Structure: metric_filters 

Define what metric to use and how many curves to display in the resulting graph.
Each option's key represents the name of a curve. Its value the path to the
metric in Icinga 2's [graphite naming schema](https://www.icinga.com/docs/icinga2/latest/doc/14-features/#current-graphite-schema).

Curve names are used to map Graphite functions to metrics. (More on this below)
However, they are fully arbitrary and have no further meaning outside template
configurations.

A curve's metric path must begin with either the macro `$host_name_template$`
or `$service_name_template$` and is substituted with Icinga 2's prefix label.
The rest of the path is arbitrary, but to get meaningful results use a valid
path to one of the performance data metrics:

    <prefix-label>.perfdata.<perfdata-label>.<metric>

An example path which points to the metric `value` of the `rta` perfdata-label
looks as follows:

    $host_name_template$.perfdata.rta.value

To dynamically render a graph for each performance data label found, define a
macro in place for the actual perfdata-label:

    $host_name_template$.perfdata.$perfdata_label$.value

You can also use wildcards. To define a wildcard, please use the following syntax:

    $macro:wildcard syntax here$
    
  Some Examples:

    $perfdata_label:{abc,def}$
    $perfdata_label:{a*c,de*}$
    $perfdata_label:{a[vbn]c,def}$

> **Note:**
>
> The name of the macro for the perfdata-label is also arbitrary. You may as
> well use a more descriptive name such as `$disk$` for the disk check. `$disk$` 
> is the same as `$disk:*$`.

### Template Structure: urlparams 

Allows to define additional URL parameters to be passed to Graphite's render
API.

Each option represents a single parameter's name and value. A list of all
supported parameters can be found [here](https://graphite.readthedocs.io/en/latest/render_api.html#graph-parameters).

If you have used a macro for the curve's perfdata-label you may utilize it
here as well:

    title = "Disk usage on $disk$"

You may also define URL parameters once for all templates
(including the shipped ones) in the `default_url_params` section in
`/etc/icingaweb2/modules/graphite/config.ini`:

    [default_url_params]
    yUnitSystem = "none"

These may be overridden in the template itself:

    yUnitSystem = "binary"

### Template Structure: functions 

Allows to define Graphite functions which are applied to the metric of a
specific curve on the graph.

Each option's key must match a curve's name in order to apply the function
to the curve's metric. A list of all supported functions can be found [here](https://graphite.readthedocs.io/en/latest/functions.html#functions).

The metric in question can be referenced in the function call using the macro
`$metric$` as shown in the following example:

    alias(color(scale($metric$, 1000), '#1a7dd7'), 'Round trip time (ms)')

In addition you may utilize all other macros here as well:

    alias(color(scale(divideSeries($metric$, $service_name_template$.perfdata.$disk$.max), 100), '#1a7dd7'), 'Used (%)')

## Template Example 

The configuration examples used in this document are borrowed from the template
for the `hostalive` check-command:

```ini
[hostalive-rta.graph]
check_command = "hostalive"

[hostalive-rta.metrics_filters]
rta.value = "$host_name_template$.perfdata.rta.value"

[hostalive-rta.urlparams]
areaAlpha = "0.5"
areaMode = "all"
min = "0"
yUnitSystem = "none"

[hostalive-rta.functions]
rta.value = "alias(color(scale($metric$, 1000), '#1a7dd7'), 'Round trip time (ms)')"


[hostalive-pl.graph]
check_command = "hostalive"

[hostalive-pl.metrics_filters]
pl.value = "$host_name_template$.perfdata.pl.value"

[hostalive-pl.urlparams]
areaAlpha = "0.5"
areaMode = "all"
min = "0"
yUnitSystem = "none"

[hostalive-pl.functions]
pl.value = "alias(color($metric$, '#1a7dd7'), 'Packet loss (%)')"
```

## Default Template Settings 

Next to maintaining templates for specific commands, you can
specify the default template settings in the [default.ini](https://github.com/Icinga/icingaweb2-module-graphite/blob/main/templates/default.ini)
configuration file.

The following example adjusts the background and foreground colors
to setup the "dark mode" for graphs.

First, copy the package provided configuration into the configuration
path. Then add the `bgcolor` and `fgcolor` settings into the [urlparams](04-Templates.md#templates-structure-urlparams)
sections for `default-host` and `default-service`.

```
cp /usr/share/icingaweb2/modules/graphite/templates/default.ini /etc/icingaweb2/modules/graphite/templates/default.ini

vim /etc/icingaweb2/modules/graphite/templates/default.ini

[default-host.urlparams]

bgcolor = "black"
fgcolor = "white"

[default-service.urlparams]

bgcolor = "black"
fgcolor = "white"
```

The settings make use the `urlparams` section which adds the
parameters to the render API.


> **Note**
>
> Instead of modifying the color settings in the default template,
> you can also change the Graphite configuration explained in
> [this community topic](https://community.icinga.com/t/how-to-adjust-the-graphite-background-color/3172/3).


## Further reading

* [Troubleshooting](05-Troubleshooting.md)
