API endpoint for Peer Monitor metrics

[hsanjuan]

Basic information

• Type (mark as appropiate):
  • Bug
  • Feature request
  • Enhancement

Description

The Peer Monitor collects metrics and stores them by type and by peer.

type PeerMonitor interface {
        Component
        // LogMetric stores a metric. It can be used to manually inject
        // a metric to a monitor.
        LogMetric(api.Metric) error
        // PublishMetric sends a metric to the rest of the peers.
        // How to send it, and to who, is to be decided by the implementation.
        PublishMetric(api.Metric) error
        // LatestMetrics returns a map with the latest metrics of matching name
        // for the current cluster peers.
        LatestMetrics(name string) []api.Metric
        // Alerts delivers alerts generated when this peer monitor detects
        // a problem (i.e. metrics not arriving as expected). Alerts can be used
        // to trigger self-healing measures or re-pinnings of content.
        Alerts() <-chan api.Alert
}

The information from LatestMetrics() should be inspectable by the user through the rest api.

This implies:

• Coming up with the right restful endpoint (GET /health/metrics/<name>)
• Implement it in the api/rest component (the metrics can be requested via RPC request to PeerMonitorLatestMetrics)
• Support the new endpoint in rest/api/client
• Support the new method in ipfs-cluster-ctl. i.e. ipfs-cluster-ctl health metrics <name> would show the peers and the last list of metrics logged for each as returned by the Peer Monitor, in a friendly way.