Move daemon ping to use native Go code
@@ -4,22 +4,28 @@ import (
"archive/tar"
"bytes"
"context"
+ "errors"
"fmt"
"io"
"io/ioutil"
"log"
+ "net"
"net/http"
+ "net/http/httputil"
"os"
- "os/exec"
"strconv"
"strings"
"time"
)
+var (
+ errDockerPingNotOK = errors.New("Docker /_ping did not return OK")
+)
+
const (
healthcheckTimeout = 5 * time.Second
dockerSock = "/var/run/docker.sock"
- lgtm = "LGTM"
+ dockerPingOK = "LGTM"
httpMagicPort = ":44554" // chosen arbitrarily due to IANA availability -- might change
bucket = "editionsdiagnostics"
sessionIDField = "session"
@@ -39,22 +45,53 @@ func init() {
// for cloud editions.
type HTTPDiagnosticListener struct{}
+// UnixSocketRoundTripper provides a way to make HTTP request to Docker socket
+// directly.
+type UnixSocketRoundTripper struct{}
+
+// RoundTrip dials the Docker UNIX socket to make a HTTP request.
+func (u UnixSocketRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+ dial, err := net.Dial("unix", dockerSock)
+ if err != nil {
+ return nil, err
+ }
+ conn := httputil.NewClientConn(dial, nil)
+ defer conn.Close()
+ return conn.Do(req)
+}
+
// Listen starts the HTTPDiagnosticListener and sets up handlers for its endpoints
func (h HTTPDiagnosticListener) Listen() {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+ client := &http.Client{
+ Transport: &UnixSocketRoundTripper{},
+ }
+
+ req, err := http.NewRequest(http.MethodGet, "/_ping", nil)
+ if err != nil {
+ http.Error(w, "Error creating HTTP request to talk to Docker", http.StatusInternalServerError)
+ return
+ }
+
ctx, cancel := context.WithTimeout(context.Background(), healthcheckTimeout)
defer cancel()
- // Vendoring the Docker Go client is overkill for this
- // small program, and we can fairly safely rely on the
- // `docker` client's existence locally, so we just
- // shell out here.
- cmd := exec.CommandContext(ctx, "docker", "info")
+ req = req.WithContext(ctx)
+
errCh := make(chan error)
go func() {
- _, err := cmd.CombinedOutput()
+ resp, err := client.Do(req)
+ if err != nil {
errCh <- err
+ return
+ }
+ defer resp.Body.Close()
+ if resp.StatusCode != http.StatusOK {
+ errCh <- errDockerPingNotOK
+ return
+ }
+ errCh <- nil
}()
select {
@@ -68,7 +105,7 @@ func (h HTTPDiagnosticListener) Listen() {
return
}
- if _, err := w.Write([]byte(lgtm)); err != nil {
+ if _, err := w.Write([]byte(dockerPingOK)); err != nil {
log.Println("Error writing HTTP success response:", err)
return
}
