YAML File - Global Variables

The YAML file used by this client is divided into several sections, each serving a distinct purpose:
Table 1. YAML File Structure
globalVariables Defines global variables that can be used throughout the YAML file.
defaultLabels Sets default labels to be applied to all metrics.
metricObjects Defines the metrics to be exposed to Prometheus, including their types and specific labels.
metricData Specifies the data points to be collected, along with any processing functions to be applied.

Overview

Global Variables in the Prometheus Client configuration are key-value pairs that provide a centralized way to define values which can be reused across the configuration.

Define Global Variables

  • Specified in the YAML configuration file under `globalVariables`.
  • Used for values that need to be consistent across various metric configurations.

Usage

  • Refer to these variables in other parts of the YAML file to maintain consistency and ease of updates.
  • Particularly useful for setting default values. See section [globalVariable].

Example

```yaml
globalVariables:
  environment: "production"
  serviceVersion: "1.2.3"
  version: !dpGet
    dpId:
      - "_DatabaseVersion.Major:_original.._value"
      - "_DatabaseVersion.Minor:_original.._value"
      - "_DatabaseVersion.Sub:_original.._value"
    fetch: onetime
    transformation: v => v.join('.')
  reduNum: ${this.wccoa.myReduHostNum()}
  systemNum: ${this.wccoa.getSystemId()}
```
This configuration for global variables in Prometheus integrates both static values and dynamic data fetching:
  1. Static values like `environment` and `serviceVersion` are directly set.
  2. Dynamic data fetching is used for `version` using `!dpGet`, combining major, minor, and sub-version numbers from the WinCC OA.

  3. `reduNum` and `systemNum` leverage WinCC OA functions (`wccoa.myReduHostNum()` and `wccoa.getSystemId()`) to dynamically assign values.