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origin_http.go
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origin_http.go
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package stargate
import (
"context"
"fmt"
"net/http"
"net/http/httputil"
"strings"
"sync"
"time"
"github.com/pkg/errors"
)
type httpOriginServer struct {
url string
backend *httputil.ReverseProxy
hcMut sync.RWMutex
alive bool
healthCheckRunning bool
}
func (origin *httpOriginServer) Address() string {
return origin.url
}
func (origin *httpOriginServer) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
origin.backend.ServeHTTP(rw, r)
}
func (origin *httpOriginServer) Healthy() bool {
origin.hcMut.RLock()
defer origin.hcMut.RUnlock()
if !origin.healthCheckRunning {
return true
}
return origin.alive
}
func (origin *httpOriginServer) Close() error {
Log.Debug("stopping health checker to %q", origin.url)
origin.healthCheckRunning = false
origin.alive = false
return nil
}
func (origin *httpOriginServer) startHealthCheck(options *HealthCheckOptions) {
interval := options.Interval
if interval == 0 {
interval = DefaultHealthCheckInterval
}
path := strings.TrimSpace(options.Path)
if path == "" {
path = DefaultHealthCheckPath
}
okStatus := options.HealthyStatus
if http.StatusText(okStatus) == "" {
okStatus = DefaultHealthCheckStatus
}
timeout := options.Timeout
if timeout <= 0 {
timeout = DefaultHealthCheckTimeout
}
unhealthyPings := options.UnhealthyPings
if unhealthyPings <= 0 {
unhealthyPings = DefaultUnhealthyPings
}
Log.Debug("pinging %q every %v at %q with a timeout of %v", origin.url, interval, path, timeout)
healthTicker := time.NewTicker(interval)
defer healthTicker.Stop()
counter := newHealthCounter(unhealthyPings)
origin.healthCheckRunning = true
for origin.healthCheckRunning {
err := origin.checkHealth(path, okStatus, timeout)
if err != nil {
Log.Error("%q: healthcheck failed: %v", origin.url, err)
counter.countUnhealthy()
} else {
counter.countHealthy()
}
origin.hcMut.Lock()
origin.alive = counter.ok()
origin.hcMut.Unlock()
<-healthTicker.C
}
}
func (origin *httpOriginServer) checkHealth(path string, status int, timeout time.Duration) error {
ctx, cancel := context.WithTimeout(context.Background(), timeout)
defer cancel()
address := fmt.Sprintf("%s/%s", origin.url, path)
req, err := http.NewRequest(http.MethodGet, address, nil)
if err != nil {
return err
}
resp, err := http.DefaultClient.Do(req.WithContext(ctx))
if err != nil {
return err
}
defer func() {
if err := resp.Body.Close(); err != nil {
Log.Error("cannot close response body of health check ping to %q: %v", address, err)
}
}()
if resp.StatusCode != status {
return errors.Errorf("invalid status %d (expected %d)", resp.StatusCode, status)
}
return nil
}