Merge pull request moby#2087 from fcrisciani/join-flag

Add an explicit flag to join network in diagnostic

cmd/diagnostic/Dockerfile.dind

@@ -1,4 +1,5 @@
 FROM docker:17.12-dind
 RUN apk add --no-cache curl
+ENV DIND_CLIENT=true
 COPY daemon.json /etc/docker/daemon.json
 COPY diagnosticClient /usr/local/bin/diagnosticClient

cmd/diagnostic/README.md

@@ -199,8 +199,18 @@ The following flags are supported:
 | -ip <string>  | The IP address to query. Defaults to 127.0.0.1. |
 | -net <string> | The target network ID.                          |
 | -port <int>   | The target port. (default port is 2000)         |
+| -a            | Join/leave network                              |
 | -v            | Enable verbose output.                          |
 
+*NOTE*
+By default the tool won't try to join the network. This is following the intent to not change
+the state on which the node is when the diagnostic client is run. This means that it is safe
+to run the diagnosticClient against a running daemon because it will just dump the current state.
+When using instead the diagnosticClient in the containerized version the flag `-a` MUST be passed
+to avoid retrieving empty results. On the other side using the `-a` flag against a loaded daemon
+will have the undesirable side effect to leave the network and so cutting down the data path for
+that daemon.
+
 ### Container version of the diagnostic tool
 
 The CLI is provided as a container with a 17.12 engine that needs to run using privileged mode.
@@ -242,11 +252,11 @@ Remember to use the full network ID, you can easily find that with `docker netwo
 **Service discovery and load balancer:**
 
 ```bash
-$ diagnostiClient -c sd -v -net n8a8ie6tb3wr2e260vxj8ncy4
+$ diagnostiClient -c sd -v -net n8a8ie6tb3wr2e260vxj8ncy4 -a
 ```
 
 **Overlay network:**
 
 ```bash
-$ diagnostiClient -port 2001 -c overlay -v -net n8a8ie6tb3wr2e260vxj8ncy4
+$ diagnostiClient -port 2001 -c overlay -v -net n8a8ie6tb3wr2e260vxj8ncy4 -a
 ```

cmd/diagnostic/main.go

@@ -45,6 +45,7 @@ func main() {
 	networkPtr := flag.String("net", "", "target network")
 	tablePtr := flag.String("t", "", "table to process <sd/overlay>")
 	remediatePtr := flag.Bool("r", false, "perform remediation deleting orphan entries")
+	joinPtr := flag.Bool("a", false, "join/leave network")
 	verbosePtr := flag.Bool("v", false, "verbose output")
 
 	flag.Parse()
@@ -53,6 +54,11 @@ func main() {
 		logrus.SetLevel(logrus.DebugLevel)
 	}
 
+	if _, ok := os.LookupEnv("DIND_CLIENT"); !ok && *joinPtr {
+		logrus.Fatal("you are not using the client in docker in docker mode, the use of the -a flag can be disruptive, " +
+			"please remove it (doc:https://github.com/docker/libnetwork/blob/master/cmd/diagnostic/README.md)")
+	}
+
 	logrus.Infof("Connecting to %s:%d checking ready", *ipPtr, *portPtr)
 	resp, err := http.Get(fmt.Sprintf(readyPath, *ipPtr, *portPtr))
 	if err != nil {
@@ -64,14 +70,20 @@ func main() {
 	var networkPeers map[string]string
 	var joinedNetwork bool
 	if *networkPtr != "" {
-		logrus.Infof("Joining the network:%s", *networkPtr)
-		resp, err = http.Get(fmt.Sprintf(joinNetwork, *ipPtr, *portPtr, *networkPtr))
-		if err != nil {
-			logrus.WithError(err).Fatalf("Failed joining the network")
+		if *joinPtr {
+			logrus.Infof("Joining the network:%q", *networkPtr)
+			resp, err = http.Get(fmt.Sprintf(joinNetwork, *ipPtr, *portPtr, *networkPtr))
+			if err != nil {
+				logrus.WithError(err).Fatalf("Failed joining the network")
+			}
+			httpIsOk(resp.Body)
+			joinedNetwork = true
 		}
-		httpIsOk(resp.Body)
+
 		networkPeers = fetchNodePeers(*ipPtr, *portPtr, *networkPtr)
-		joinedNetwork = true
+		if len(networkPeers) == 0 {
+			logrus.Warnf("There is no peer on network %q, check the network ID, and verify that is the non truncated version", *networkPtr)
+		}
 	}
 
 	switch *tablePtr {
@@ -82,6 +94,7 @@ func main() {
 	}
 
 	if joinedNetwork {
+		logrus.Infof("Leaving the network:%q", *networkPtr)
 		resp, err = http.Get(fmt.Sprintf(leaveNetwork, *ipPtr, *portPtr, *networkPtr))
 		if err != nil {
 			logrus.WithError(err).Fatalf("Failed leaving the network")
@@ -91,7 +104,12 @@ func main() {
 }
 
 func fetchNodePeers(ip string, port int, network string) map[string]string {
-	logrus.Infof("Fetch peers %s", network)
+	if network == "" {
+		logrus.Infof("Fetch cluster peers")
+	} else {
+		logrus.Infof("Fetch peers network:%q", network)
+	}
+
 	var path string
 	if network != "" {
 		path = fmt.Sprintf(networkPeers, ip, port, network)