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package internal
import (
"context"
"encoding/json"
"fmt"
"net/http"
"net/url"
"os"
"time"
)
type peerReport struct {
LastUpdated string `json:"lastUpdated"`
}
func peerActive(ctx context.Context, conf config) (bool, string) {
if conf.PeerURL == "" {
return true, "Peer failover: disabled (PeerURL not set)"
}
hostname, err := os.Hostname()
if err != nil {
return true, fmt.Sprintf("Peer failover: hostname lookup failed (%v); staying active", err)
}
return peerActiveAt(ctx, conf, time.Now(), hostname, fetchPeerLastUpdated)
}
func peerActiveAt(
ctx context.Context,
conf config,
now time.Time,
hostname string,
fetch func(context.Context, string) (time.Time, error),
) (bool, string) {
if conf.PeerURL == "" {
return true, "Peer failover: disabled (PeerURL not set)"
}
primary := conf.PeerPrimaryName
if primary == "" {
primary = hostname
}
secondary := conf.PeerSecondaryName
if secondary == "" {
if parsedURL, err := url.Parse(conf.PeerURL); err == nil && parsedURL.Hostname() != "" {
secondary = parsedURL.Hostname()
}
}
if primary == "" || secondary == "" {
return true, "Peer failover: missing peer names; staying active"
}
if hostname != primary && hostname != secondary {
return true, fmt.Sprintf("Peer failover: local hostname %s not in [%s, %s]; staying active",
hostname, primary, secondary)
}
staleThresholdS := conf.PeerStaleThresholdS
if staleThresholdS == 0 {
staleThresholdS = 600
}
lastUpdated, err := fetch(ctx, conf.PeerURL)
if err != nil {
return true, fmt.Sprintf("Peer failover: peer check failed (%v); staying active", err)
}
age := now.Sub(lastUpdated)
if age > time.Duration(staleThresholdS)*time.Second {
return true, fmt.Sprintf("Peer failover: peer stale (%v > %ds); staying active",
age, staleThresholdS)
}
master := scheduledMaster(primary, secondary, now)
if hostname == master {
return true, fmt.Sprintf("Peer failover: peer healthy; scheduled master is %s", master)
}
return false, fmt.Sprintf("Peer failover: peer healthy; scheduled master is %s", master)
}
func scheduledMaster(primary, secondary string, now time.Time) string {
week := weekNumberSunday(now)
if week%2 == 0 {
return secondary
}
return primary
}
// weekNumberSunday matches strftime %U (Sunday-based week number, 00-53).
func weekNumberSunday(t time.Time) int {
tUTC := t.In(time.UTC)
yearStart := time.Date(tUTC.Year(), 1, 1, 0, 0, 0, 0, time.UTC)
// Find the first Sunday on or after Jan 1.
daysUntilSunday := (7 - int(yearStart.Weekday())) % 7
firstSunday := yearStart.AddDate(0, 0, daysUntilSunday)
if tUTC.Before(firstSunday) {
return 0
}
daysSinceFirstSunday := int(tUTC.Sub(firstSunday).Hours() / 24)
return 1 + (daysSinceFirstSunday / 7)
}
func fetchPeerLastUpdated(ctx context.Context, peerURL string) (time.Time, error) {
req, err := http.NewRequestWithContext(ctx, http.MethodGet, peerURL, nil)
if err != nil {
return time.Time{}, err
}
client := http.Client{
Timeout: 5 * time.Second,
}
resp, err := client.Do(req)
if err != nil {
return time.Time{}, err
}
defer resp.Body.Close()
if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
return time.Time{}, fmt.Errorf("unexpected status %d", resp.StatusCode)
}
var report peerReport
if err := json.NewDecoder(resp.Body).Decode(&report); err != nil {
return time.Time{}, err
}
if report.LastUpdated == "" {
return time.Time{}, fmt.Errorf("missing lastUpdated")
}
lastUpdated, err := time.Parse(time.RFC3339, report.LastUpdated)
if err != nil {
return time.Time{}, err
}
return lastUpdated, nil
}
|
