fix: catch more ssh failure modes with help

cli/internal/cli.go

@@ -410,6 +410,24 @@ Good luck!
 
 `
 
+var ServerAddFailMsg = `
+Failed to add server %s.
+
+This could be caused by two things.
+
+Abra isn't picking up your SSH configuration or you need to specify it on the
+command-line (e.g you use a non-standard port or username to connect). Run
+"server add" with "-d/--debug" to learn more about what Abra is doing under the
+hood.
+
+Docker is not installed on your server. You can pass "-p/--provision" to
+install Docker and initialise Docker Swarm mode. See help output for "server
+add"
+
+See "abra server add -h" for more.
+
+`
+
 // SubCommandBefore wires up pre-action machinery (e.g. --debug handling).
 func SubCommandBefore(c *cli.Context) error {
 	if Debug {

cli/server/add.go

@@ -463,14 +463,17 @@ developer machine.
 
 		cl, err := newClient(c, domainName)
 		if err != nil {
-			logrus.Fatal(err)
+			cleanUp(domainName)
+			logrus.Debugf("failed to construct client for %s, saw %s", domainName, err.Error())
+			logrus.Fatalf(fmt.Sprintf(internal.ServerAddFailMsg, domainName))
 		}
 
 		if provision {
 			logrus.Debugf("attempting to construct SSH client for %s", domainName)
 			sshCl, err := ssh.New(domainName, sshAuth, username, port)
 			if err != nil {
-				logrus.Fatal(err)
+				cleanUp(domainName)
+				logrus.Fatalf(fmt.Sprintf(internal.ServerAddFailMsg, domainName))
 			}
 			defer sshCl.Close()
 			logrus.Debugf("successfully created SSH client for %s", domainName)
@@ -485,7 +488,7 @@ developer machine.
 
 		if _, err := cl.Info(context.Background()); err != nil {
 			cleanUp(domainName)
-			logrus.Fatalf("couldn't make a remote docker connection to %s? use --provision/-p to attempt to install", domainName)
+			logrus.Fatalf(fmt.Sprintf(internal.ServerAddFailMsg, domainName))
 		}
 
 		return nil