middleware/proxy: Allow non-HTTP upstreams to be health checked (#589)
Allow HTTP health check to be performed against a regular DNS upstream server. TODO: Add tests.
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parent
36c743a4d8
commit
dfc71df07d
2 changed files with 124 additions and 6 deletions
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@ -4,8 +4,10 @@ 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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"strconv"
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"strings"
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"sync/atomic"
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@ -14,7 +16,6 @@ import (
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"github.com/coredns/coredns/middleware"
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"github.com/coredns/coredns/middleware/pkg/dnsutil"
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"github.com/coredns/coredns/middleware/pkg/tls"
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"github.com/mholt/caddy/caddyfile"
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"github.com/miekg/dns"
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)
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@ -229,16 +230,38 @@ func parseBlock(c *caddyfile.Dispenser, u *staticUpstream) error {
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func (u *staticUpstream) healthCheck() {
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for _, host := range u.Hosts {
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port := ""
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if u.HealthCheck.Port != "" {
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port = ":" + u.HealthCheck.Port
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var hostName, checkPort string
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// The DNS server might be an HTTP server. If so, extract its name.
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if url, err := url.Parse(host.Name); err == nil {
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hostName = url.Host
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} else {
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hostName = host.Name
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}
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hostURL := host.Name + port + u.HealthCheck.Path
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// Extract the port number from the parsed server name.
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checkHostName, checkPort, err := net.SplitHostPort(hostName)
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if err != nil {
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checkHostName = hostName
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}
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if u.HealthCheck.Port != "" {
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checkPort = u.HealthCheck.Port
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}
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hostURL := "http://" + net.JoinHostPort(checkHostName, checkPort) + u.HealthCheck.Path
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host.Unhealthy = false
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if r, err := http.Get(hostURL); err == nil {
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io.Copy(ioutil.Discard, r.Body)
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r.Body.Close()
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host.Unhealthy = r.StatusCode < 200 || r.StatusCode >= 400
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if r.StatusCode < 200 || r.StatusCode >= 400 {
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log.Printf("[WARNING] Health check URL %s returned HTTP code %d\n",
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hostURL, r.StatusCode)
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host.Unhealthy = true
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}
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} else {
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log.Printf("[WARNING] Health check probe failed: %v\n", err)
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host.Unhealthy = true
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}
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}
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95
test/proxy_http_health_test.go
Normal file
95
test/proxy_http_health_test.go
Normal file
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@ -0,0 +1,95 @@
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package test
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import (
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"io"
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"io/ioutil"
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"log"
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"net/http"
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"net/http/httptest"
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"net/url"
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"testing"
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"github.com/coredns/coredns/middleware/proxy"
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"github.com/coredns/coredns/middleware/test"
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"github.com/coredns/coredns/request"
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"github.com/miekg/dns"
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)
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func TestProxyWithHTTPCheckOK(t *testing.T) {
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log.SetOutput(ioutil.Discard)
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healthCheckServer := httptest.NewServer(http.HandlerFunc(
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func(w http.ResponseWriter, r *http.Request) {
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w.WriteHeader(http.StatusOK)
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io.WriteString(w, "OK\n")
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}))
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defer healthCheckServer.Close()
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healthCheckURL, err := url.Parse(healthCheckServer.URL)
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if err != nil {
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t.Fatal(err)
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}
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healthCheckPort := healthCheckURL.Port()
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name, rm, err := test.TempFile(".", exampleOrg)
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if err != nil {
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t.Fatalf("failed to create zone: %s", err)
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}
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defer rm()
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// We have to bind to 127.0.0.1 because the server started by
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// httptest.NewServer does, and the IP addresses of the backend
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// DNS and HTTP servers must match.
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authoritativeCorefile := `example.org:0 {
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bind 127.0.0.1
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file ` + name + `
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}
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`
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authoritativeInstance, err := CoreDNSServer(authoritativeCorefile)
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if err != nil {
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t.Fatalf("Could not get CoreDNS authoritative instance: %s", err)
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}
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authoritativeAddr, _ := CoreDNSServerPorts(authoritativeInstance, 0)
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if authoritativeAddr == "" {
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t.Fatalf("Could not get CoreDNS authoritative instance UDP listening port")
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}
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defer authoritativeInstance.Stop()
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proxyCorefile := `example.org:0 {
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proxy . ` + authoritativeAddr + ` {
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health_check /health:` + healthCheckPort + ` 1s
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}
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}
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`
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proxyInstance, err := CoreDNSServer(proxyCorefile)
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if err != nil {
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t.Fatalf("Could not get CoreDNS proxy instance: %s", err)
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}
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proxyAddr, _ := CoreDNSServerPorts(proxyInstance, 0)
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if proxyAddr == "" {
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t.Fatalf("Could not get CoreDNS proxy instance UDP listening port")
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}
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defer proxyInstance.Stop()
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p := proxy.NewLookup([]string{proxyAddr})
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state := request.Request{W: &test.ResponseWriter{}, Req: new(dns.Msg)}
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resp, err := p.Lookup(state, "example.org.", dns.TypeA)
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if err != nil {
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t.Fatal("Expected to receive reply, but didn't")
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}
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// expect answer section with A record in it
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if len(resp.Answer) == 0 {
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t.Fatalf("Expected to at least one RR in the answer section, got none: %s", resp)
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}
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if resp.Answer[0].Header().Rrtype != dns.TypeA {
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t.Errorf("Expected RR to A, got: %d", resp.Answer[0].Header().Rrtype)
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}
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if resp.Answer[0].(*dns.A).A.String() != "127.0.0.1" {
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t.Errorf("Expected 127.0.0.1, got: %s", resp.Answer[0].(*dns.A).A.String())
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}
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}
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