2019-09-03 13:10:11 -05:00
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// Copyright 2015 Matthew Holt and The Caddy Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package reverseproxy
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import (
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"net"
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"net/http"
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"net/url"
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"regexp"
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"strconv"
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"time"
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"github.com/caddyserver/caddy/v2"
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"github.com/caddyserver/caddy/v2/modules/caddyhttp"
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)
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2019-09-03 17:56:09 -05:00
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// HealthChecks holds configuration related to health checking.
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2019-09-03 13:10:11 -05:00
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type HealthChecks struct {
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Active *ActiveHealthChecks `json:"active,omitempty"`
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Passive *PassiveHealthChecks `json:"passive,omitempty"`
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}
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2019-09-03 17:56:09 -05:00
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// ActiveHealthChecks holds configuration related to active
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// health checks (that is, health checks which occur in a
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// background goroutine independently).
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2019-09-03 13:10:11 -05:00
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type ActiveHealthChecks struct {
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Path string `json:"path,omitempty"`
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Port int `json:"port,omitempty"`
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Interval caddy.Duration `json:"interval,omitempty"`
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Timeout caddy.Duration `json:"timeout,omitempty"`
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MaxSize int64 `json:"max_size,omitempty"`
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ExpectStatus int `json:"expect_status,omitempty"`
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ExpectBody string `json:"expect_body,omitempty"`
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stopChan chan struct{}
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httpClient *http.Client
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bodyRegexp *regexp.Regexp
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}
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2019-09-03 17:56:09 -05:00
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// PassiveHealthChecks holds configuration related to passive
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// health checks (that is, health checks which occur during
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// the normal flow of request proxying).
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2019-09-03 13:10:11 -05:00
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type PassiveHealthChecks struct {
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MaxFails int `json:"max_fails,omitempty"`
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FailDuration caddy.Duration `json:"fail_duration,omitempty"`
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UnhealthyRequestCount int `json:"unhealthy_request_count,omitempty"`
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UnhealthyStatus []int `json:"unhealthy_status,omitempty"`
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UnhealthyLatency caddy.Duration `json:"unhealthy_latency,omitempty"`
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}
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2019-09-03 20:06:54 -05:00
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// CircuitBreaker is a type that can act as an early-warning
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// system for the health checker when backends are getting
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// overloaded.
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type CircuitBreaker interface {
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OK() bool
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RecordMetric(statusCode int, latency time.Duration)
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}
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2019-09-03 17:56:09 -05:00
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// activeHealthChecker runs active health checks on a
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// regular basis and blocks until
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// h.HealthChecks.Active.stopChan is closed.
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2019-09-03 13:10:11 -05:00
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func (h *Handler) activeHealthChecker() {
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ticker := time.NewTicker(time.Duration(h.HealthChecks.Active.Interval))
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h.doActiveHealthChecksForAllHosts()
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for {
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select {
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case <-ticker.C:
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h.doActiveHealthChecksForAllHosts()
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case <-h.HealthChecks.Active.stopChan:
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ticker.Stop()
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return
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}
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}
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}
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2019-09-03 17:56:09 -05:00
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// doActiveHealthChecksForAllHosts immediately performs a
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// health checks for all hosts in the global repository.
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func (h *Handler) doActiveHealthChecksForAllHosts() {
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hosts.Range(func(key, value interface{}) bool {
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addr := key.(string)
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host := value.(Host)
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go func(addr string, host Host) {
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err := h.doActiveHealthCheck(addr, host)
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if err != nil {
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log.Printf("[ERROR] reverse_proxy: active health check for host %s: %v", addr, err)
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}
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}(addr, host)
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// continue to iterate all hosts
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return true
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})
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}
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// doActiveHealthCheck performs a health check to host which
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// can be reached at address hostAddr. The actual address for
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// the request will be built according to active health checker
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// config. The health status of the host will be updated
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// according to whether it passes the health check. An error is
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// returned only if the health check fails to occur or if marking
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// the host's health status fails.
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func (h *Handler) doActiveHealthCheck(hostAddr string, host Host) error {
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// create the URL for the health check
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u, err := url.Parse(hostAddr)
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if err != nil {
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return err
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}
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if h.HealthChecks.Active.Path != "" {
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u.Path = h.HealthChecks.Active.Path
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}
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if h.HealthChecks.Active.Port != 0 {
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portStr := strconv.Itoa(h.HealthChecks.Active.Port)
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u.Host = net.JoinHostPort(u.Hostname(), portStr)
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}
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req, err := http.NewRequest(http.MethodGet, u.String(), nil)
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if err != nil {
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return err
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}
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// do the request, careful to tame the response body
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resp, err := h.HealthChecks.Active.httpClient.Do(req)
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if err != nil {
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log.Printf("[INFO] reverse_proxy: active health check: %s is down (HTTP request failed: %v)", hostAddr, err)
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_, err2 := host.SetHealthy(false)
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if err2 != nil {
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return fmt.Errorf("marking unhealthy: %v", err2)
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}
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return nil
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}
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var body io.Reader = resp.Body
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if h.HealthChecks.Active.MaxSize > 0 {
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body = io.LimitReader(body, h.HealthChecks.Active.MaxSize)
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}
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defer func() {
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// drain any remaining body so connection can be re-used
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io.Copy(ioutil.Discard, body)
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resp.Body.Close()
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}()
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// if status code is outside criteria, mark down
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if h.HealthChecks.Active.ExpectStatus > 0 {
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if !caddyhttp.StatusCodeMatches(resp.StatusCode, h.HealthChecks.Active.ExpectStatus) {
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log.Printf("[INFO] reverse_proxy: active health check: %s is down (status code %d unexpected)", hostAddr, resp.StatusCode)
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_, err := host.SetHealthy(false)
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if err != nil {
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return fmt.Errorf("marking unhealthy: %v", err)
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}
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return nil
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}
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} else if resp.StatusCode < 200 || resp.StatusCode >= 400 {
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log.Printf("[INFO] reverse_proxy: active health check: %s is down (status code %d out of tolerances)", hostAddr, resp.StatusCode)
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_, err := host.SetHealthy(false)
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if err != nil {
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return fmt.Errorf("marking unhealthy: %v", err)
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}
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return nil
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}
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// if body does not match regex, mark down
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if h.HealthChecks.Active.bodyRegexp != nil {
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bodyBytes, err := ioutil.ReadAll(body)
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if err != nil {
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log.Printf("[INFO] reverse_proxy: active health check: %s is down (failed to read response body)", hostAddr)
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_, err := host.SetHealthy(false)
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if err != nil {
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return fmt.Errorf("marking unhealthy: %v", err)
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}
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return nil
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}
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if !h.HealthChecks.Active.bodyRegexp.Match(bodyBytes) {
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log.Printf("[INFO] reverse_proxy: active health check: %s is down (response body failed expectations)", hostAddr)
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_, err := host.SetHealthy(false)
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if err != nil {
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return fmt.Errorf("marking unhealthy: %v", err)
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}
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return nil
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}
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}
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// passed health check parameters, so mark as healthy
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swapped, err := host.SetHealthy(true)
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if swapped {
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log.Printf("[INFO] reverse_proxy: active health check: %s is back up", hostAddr)
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}
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if err != nil {
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return fmt.Errorf("marking healthy: %v", err)
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}
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return nil
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}
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// countFailure is used with passive health checks. It
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// remembers 1 failure for upstream for the configured
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// duration. If passive health checks are disabled or
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// failure expiry is 0, this is a no-op.
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func (h *Handler) countFailure(upstream *Upstream) {
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// only count failures if passive health checking is enabled
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// and if failures are configured have a non-zero expiry
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if h.HealthChecks == nil || h.HealthChecks.Passive == nil {
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return
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}
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failDuration := time.Duration(h.HealthChecks.Passive.FailDuration)
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if failDuration == 0 {
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return
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}
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// count failure immediately
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err := upstream.Host.CountFail(1)
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if err != nil {
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log.Printf("[ERROR] proxy: upstream %s: counting failure: %v",
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upstream.hostURL, err)
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}
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// forget it later
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go func(host Host, failDuration time.Duration) {
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time.Sleep(failDuration)
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err := host.CountFail(-1)
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if err != nil {
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log.Printf("[ERROR] proxy: upstream %s: expiring failure: %v",
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upstream.hostURL, err)
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}
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}(upstream.Host, failDuration)
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}
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