v0.4.2 - improved datasource and ERB template support

This release is dedicated to support different datasources properly. Additionally it contains an improved ERB interface.

• breaking changes
  • renamed global grafana-default-timeout asciidoctor variable to grafana_default_timeout to be consistent with other variable namings
• new features
  • now supporting custom datasource plugin implementations, including validation of return types and catching errors in case of datasource implementation internal issues
  • add support for InfluxDB raw queries (composed queries still on the roadmap)
  • add multiple column support for Graphite datasources
  • add multiple column support for Prometheus datasources
  • now row_divider and column_divider attributes are also respected for alert and annotation queries (as it has always been documented...)
• improvements
  • show error message if replace_values is called with a malformed regex
  • handle properly, if a dashboard datasource is not known to the reporter
  • improve README
  • ERB templates can now be created with easier syntax, e.g.

<%
dashboard = '<<your_dashboard_id>>'
instance = 'default'
panel = @report.grafana(instance).dashboard(dashboard).panel(<<your_panel_id>>)
query = QueryValueQuery.new(panel, variables: { 'result_type' => 'panel_value', 'query' => '<<your_panel_letter>>' })
%>
This is a test <%= query.execute %>.

• bugfixes
  • handle image rendering properly, if grafana cannot render an image
  • fixed SQL table column header generation
• nerd stuff
  • ERB environment is now running in a jail object binding, to handle available functions in templates easier
  • improved test coverage
  • DRYed and refactored code

Have fun!