etcdhttp: add config/local/log endpoint

PUT on the endpoint sets the GlobalDebugLevel to json level value.
The action overwrites the origianl log level setting from
users. We need to write doc to warn this.

etcdserver/etcdhttp/client.go

@@ -27,6 +27,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/coreos/pkg/capnslog"
 	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/jonboulle/clockwork"
 	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus"
 	"github.com/coreos/etcd/Godeps/_workspace/src/golang.org/x/net/context"
@@ -52,6 +53,7 @@ const (
 	metricsPath              = "/metrics"
 	healthPath               = "/health"
 	versionPath              = "/version"
+	configPath               = "/config"
 )
 
 // NewClientHandler generates a muxed http.Handler with the given parameters to serve etcd client requests.
@@ -98,6 +100,7 @@ func NewClientHandler(server *etcdserver.EtcdServer) http.Handler {
 	mux.HandleFunc(statsPrefix+"/self", sh.serveSelf)
 	mux.HandleFunc(statsPrefix+"/leader", sh.serveLeader)
 	mux.HandleFunc(varsPath, serveVars)
+	mux.HandleFunc(configPath+"/local/log", logHandleFunc)
 	mux.Handle(metricsPath, prometheus.Handler())
 	mux.Handle(membersPrefix, mh)
 	mux.Handle(membersPrefix+"/", mh)
@@ -383,6 +386,30 @@ func serveVersion(w http.ResponseWriter, r *http.Request, clusterV string) {
 	w.Write(b)
 }
 
+func logHandleFunc(w http.ResponseWriter, r *http.Request) {
+	if !allowMethod(w, r.Method, "PUT") {
+		return
+	}
+
+	in := struct{ Level string }{}
+
+	d := json.NewDecoder(r.Body)
+	if err := d.Decode(&in); err != nil {
+		writeError(w, httptypes.NewHTTPError(http.StatusBadRequest, "Invalid json body"))
+		return
+	}
+
+	logl, err := capnslog.ParseLevel(strings.ToUpper(in.Level))
+	if err != nil {
+		writeError(w, httptypes.NewHTTPError(http.StatusBadRequest, "Invalid log level "+in.Level))
+		return
+	}
+
+	plog.Noticef("globalLogLevel set to %q", logl.String())
+	capnslog.SetGlobalLogLevel(logl)
+	w.WriteHeader(http.StatusNoContent)
+}
+
 // parseKeyRequest converts a received http.Request on keysPrefix to
 // a server Request, performing validation of supplied fields as appropriate.
 // If any validation fails, an empty Request and non-nil error is returned.