Currently, Promxy generates hardcoded Prometheus-style GeneratorURLs for alerts, limiting integration with third-party alert UIs and workflows.

What's Missing with the Current Behavior?

1. Integration with Alerting UIs

   • Users might want to land on pages of other alert presentation and management software such as grafana alerting dashboards, alerts, other solutions
   • URLs cannot be customized based on context (labels like severity, team, or annotations).

2. Hardcoded Implementation Limitations

   • GeneratorURL is hardcoded in sendAlerts function
   • No configuration options available

Proposed Solution

Enable configurable Go templates for generatorURL: Support templates via CLI, config file, or external directory/file, and choose templates via alert labels/annotations.

Use Cases

1. Grafana Integration

   Direct users to specific alert in Grafana alerting interface

   https://grafana.example.com/alerting/groups?queryString=alertname%3D"{{.AlertName}}"%20cluster%3D"{{.Labels.cluster}}"
   

2. Incident Management Integration

   Route critical alerts directly to IRM systems

   https://company.pagerduty.com/incidents/new?alert={{.AlertName}}&severity={{.Labels.severity}}
   
   
   https://grafana.example.com/d/cpu-dashboard?var-instance={{.Labels.instance}}

3. Multi-Tenant Environments

   Route alerts to tenant-specific dashboards

   # URL includes tenant context
   https://{{.Labels.tenant}}.grafana.company.com/alerting/groups?alert={{.AlertName}}

Implementation Details

Configuration Structure (example)

promxy:
  alert_templates:
    # Default template used when no rules match
    default: "{{.ExternalURL}}/graph?g0.expr={{.Expr|urlquery}}&g0.tab=1"
    
    # Directory containing template files (*.tmpl)
    directory: "/etc/promxy/templates"
    
    # Named inline templates
    named:
      grafana: "https://grafana.example.com/d/alerts?alertname={{.AlertName|urlquery}}&severity={{.Labels.severity|urlquery}}"
      pagerduty: "https://pagerduty.example.com/incidents/new?title={{.AlertName|urlquery}}&description={{.Annotations.summary|urlquery}}"
      custom_dashboard: "https://monitoring.example.com/alerts/{{.AlertName}}?instance={{.Labels.instance|urlpath}}"
    
    # Template selection rules (evaluated top-to-bottom)
    rules:
      # Critical alerts go to PagerDuty
      - match_labels:
          severity: "critical"
        template: "pagerduty"
      
      # Frontend team alerts go to Grafana
      - match_labels:
          team: "frontend"
        template: "grafana"
      
      # Infrastructure alerts use custom dashboard
      - match_labels:
          component: "infrastructure"
        template: "custom_dashboard"
      
      # Inline template for specific alert
      - match_labels:
          alertname: "DatabaseDown"
        template: "https://db-dashboard.example.com/status?db={{.Labels.database|urlquery}}"

CLI Override Support

promxy --rules.alert.generator-url-template='https://grafana.example.com/alerting/groups?queryString=alertname%3D"{{.AlertName | urlquery}}"'

Template Directory

promxy --rules.alert.template-dir=/etc/promxy/templates

Template File Support

Templates can be loaded from a directory (template_directory) or specified inline under templates:.
Template selection logic can be driven by alert labels or annotations (template_rules).

Template Variables

type TemplateData struct {
    ExternalURL  string            // Promxy's external URL
    Expr         string                  // The PromQL expression that triggered the alert
    Labels       map[string]string     // Alert labels (alertname, instance, etc.)
    Annotations  map[string]string // Alert annotations (summary, description, etc.)
    AlertName    string
}

Template Functions

• urlquery: URL-encode for query params
• urlpath: URL-encode for path segments
• Standard Go template funcs.
• importing or implementing helpers from Prometheus/VictoriaMetrics (humanize, toUpper, etc.)

Backward Compatibility

If no template is supplied, Promxy continues using the current Prometheus-style GeneratorURL logic.