TUN-1350: Enhance error messages with cloudflarestatus.com link, if relevant

origin/cloudflare_status_page.go

@@ -0,0 +1,117 @@
+package origin
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/cloudflare/golibs/lrucache"
+)
+
+// StatusPage.io API docs:
+// https://www.cloudflarestatus.com/api/v2/#incidents-unresolved
+const (
+	activeIncidentsURL    = "https://yh6f0r4529hb.statuspage.io/api/v2/incidents/unresolved.json"
+	argoTunnelKeyword     = "argo tunnel"
+	incidentDetailsPrefix = "https://www.cloudflarestatus.com/incidents/"
+)
+
+// IncidentLookup is an object that checks for active incidents in
+// the Cloudflare infrastructure.
+type IncidentLookup interface {
+	ActiveIncidents() []Incident
+}
+
+// NewIncidentLookup returns a new IncidentLookup instance that caches its
+// results with a 1-minute TTL.
+func NewIncidentLookup() IncidentLookup {
+	return newCachedIncidentLookup(fetchActiveIncidents)
+}
+
+type IncidentUpdate struct {
+	Body string
+}
+
+type Incident struct {
+	Name    string
+	ID      string           `json:"id"`
+	Updates []IncidentUpdate `json:"incident_updates"`
+}
+
+type StatusPage struct {
+	Incidents []Incident
+}
+
+func (i Incident) URL() string {
+	return incidentDetailsPrefix + i.ID
+}
+
+func parseStatusPage(data []byte) (*StatusPage, error) {
+	var result StatusPage
+	err := json.Unmarshal(data, &result)
+	return &result, err
+}
+
+func isArgoTunnelIncident(i Incident) bool {
+	if strings.Contains(strings.ToLower(i.Name), argoTunnelKeyword) {
+		return true
+	}
+	for _, u := range i.Updates {
+		if strings.Contains(strings.ToLower(u.Body), argoTunnelKeyword) {
+			return true
+		}
+	}
+	return false
+}
+
+func fetchActiveIncidents() (incidents []Incident) {
+	resp, err := http.Get(activeIncidentsURL)
+	if err != nil {
+		return
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return
+	}
+	statusPage, err := parseStatusPage(body)
+	if err != nil {
+		return
+	}
+	for _, i := range statusPage.Incidents {
+		if isArgoTunnelIncident(i) {
+			incidents = append(incidents, i)
+		}
+	}
+	return incidents
+}
+
+type cachedIncidentLookup struct {
+	cache          *lrucache.LRUCache
+	ttl            time.Duration
+	uncachedLookup func() []Incident
+}
+
+func newCachedIncidentLookup(uncachedLookup func() []Incident) *cachedIncidentLookup {
+	return &cachedIncidentLookup{
+		cache:          lrucache.NewLRUCache(1),
+		ttl:            time.Minute,
+		uncachedLookup: uncachedLookup,
+	}
+}
+
+// We only need one cache entry. Always use the empty string as its key.
+const cacheKey = ""
+
+func (c *cachedIncidentLookup) ActiveIncidents() []Incident {
+	if cached, ok := c.cache.GetNotStale(cacheKey); ok {
+		if incidents, ok := cached.([]Incident); ok {
+			return incidents
+		}
+	}
+	incidents := c.uncachedLookup()
+	c.cache.Set(cacheKey, incidents, time.Now().Add(c.ttl))
+	return incidents
+}