Support Grafana Template Variables

[YKawesome]

Description

Adds functionality for users to create text-based variables which are substituted at runtime via Grafana to allow for more dynamic queries/dashboards.

Changes

• TelemetryFields.tsx
  • Updates channelValues to construct new ComboboxOptions for variables
  • Adds getChannelOptionsWithVariables to remove normal channel options when variables are being used
  • Updates onChannelChange to parse custom channel constructions by matching against any component.channel pairs
  • Uses the MultiCombobox custom value/description protocol to create new options when users use variables
  • Adds visual autocomplete using infoOptions to show valid variable choices/combinations as users type
• datasource.ts
  • Loads template variables into the query at runtime
  • Shows the Key selector when a variable query resolution results in multi-key channels
  • Updates a useEffect to add a dependency for resolved channels so that changing variable values updates the key dropdown
• QueryEditor.test.tsx
  • Mocks @grafana/runtime using a custom getTemplateSrv stub

Screenshots

Notes

Warning

This feature has only been tested with Text Box variables.

Closes #113

[github-actions]

Grafana plugin dev build

A development build of the Grafana datasource plugin is available for this PR (updated on every push).

• Release: grafana-plugin-pr-124
• Download: nasa-hermes-datasource.zip
• Commit: 225e17c

To try it, set GF_INSTALL_PLUGINS to https://github.com/nasa/hermes/releases/download/grafana-plugin-pr-124/nasa-hermes-datasource.zip;nasa-hermes-datasource.