llmgw/internal/web/dashboard.go

package web

import (
	"context"
	"log/slog"
	"net/http"
	"time"

	"gitea.mynodes.xyz/ilker/llmgw/internal/control/adminapi"
	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
)

// DashboardData is the whole page.
type DashboardData struct {
	Nodes    []adminapi.NodeView
	Models   []adminapi.ModelView
	Replicas []adminapi.ReplicaView
	Unplaced []adminapi.ExplainView
	Usage    []store.KeyUsage

	NodeCount     int
	ModelCount    int
	ReadyReplicas int
	TotalReplicas int

	AuthEnabled bool
	RefreshSec  int
	Version     string
	Now         string
}

// Source is what the dashboard reads. An interface so the page can be rendered
// in a test without a control plane.
type Source interface {
	Nodes() []adminapi.NodeView
	Models() []adminapi.ModelView
	Replicas(model string) []adminapi.ReplicaView
	Explain(model string) adminapi.ExplainView
}

// UsageSource is the accounting half, absent when authentication is off.
type UsageSource interface {
	UsageSince(ctx context.Context, since time.Time) ([]store.KeyUsage, error)
}

// Dashboard serves the read-only cluster view.
//
// It belongs on the admin listener and nowhere else. That listener is bound to
// loopback by default and also serves pprof, which can dump the process heap —
// where API keys live in plaintext. Exposing this page publicly would mean
// exposing that, so reaching it from elsewhere is an SSH tunnel's job:
//
//	ssh -L 9090:127.0.0.1:9090 llmgw-ctl
//
// Read-only on purpose. Anything that mints a credential stays in `llmgw keys`,
// where it needs a shell on the machine rather than a browser session this
// project has no way to authenticate.
func Dashboard(src Source, usage UsageSource, version string, refresh time.Duration,
	log *slog.Logger,
) http.HandlerFunc {
	if log == nil {
		log = slog.Default()
	}
	if refresh <= 0 {
		refresh = 5 * time.Second
	}
	return func(w http.ResponseWriter, r *http.Request) {
		d := DashboardData{
			RefreshSec:  int(refresh.Seconds()),
			Version:     version,
			Now:         time.Now().UTC().Format(time.RFC3339),
			AuthEnabled: usage != nil,
		}
		if src != nil {
			d.Nodes = src.Nodes()
			d.Models = src.Models()
			d.Replicas = src.Replicas("")
			d.NodeCount = len(d.Nodes)
			d.ModelCount = len(d.Models)
			d.TotalReplicas = len(d.Replicas)
			for _, rep := range d.Replicas {
				if rep.State == "ready" {
					d.ReadyReplicas++
				}
			}
			d.Unplaced = unplaced(src, d.Models)
		}
		if usage != nil {
			rows, err := usage.UsageSince(r.Context(), time.Now().Add(-24*time.Hour))
			if err != nil {
				// A reporting query failing must not take the page with it: the
				// cluster state above is what someone is most likely here for.
				log.Warn("could not read usage for the dashboard", "err", err)
			}
			d.Usage = rows
		}
		render(w, "dashboard", d)
	}
}

// unplaced collects the placement explanations for models short of replicas.
//
// Only for those: asking why a satisfied model was not placed produces an empty
// answer, and a page full of empty answers hides the one that matters.
func unplaced(src Source, models []adminapi.ModelView) []adminapi.ExplainView {
	var out []adminapi.ExplainView
	for _, m := range models {
		if m.Ready >= m.Min {
			continue
		}
		if e := src.Explain(m.Name); len(e.Rejections) > 0 {
			out = append(out, e)
		}
	}
	return out
}