17682: Fix stutter in "arvados-client shell" output.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curii.com>

diff --git a/cmd/arvados-client/container_gateway.go b/cmd/arvados-client/container_gateway.go
index e3b6b9332c23c92c0d62ab9417c3af6d56d0c9c2..5359e00c66052d25512e89bd85906b268b1360e1 100644 (file)
--- a/cmd/arvados-client/container_gateway.go
+++ b/cmd/arvados-client/container_gateway.go
@@ -67,13 +67,19 @@ Options:
        // kex_exchange_identification: Connection closed by remote host
        // Connection closed by UNKNOWN port 65535
        // exit status 255
+       //
+       // In case our target is a container request, the probe also
+       // resolves it to a container, so we don't connect to two
+       // different containers in a race.
+       var probetarget bytes.Buffer
        exitcode := connectSSHCommand{}.RunCommand(
                "arvados-client connect-ssh",
                []string{"-detach-keys=" + *detachKeys, "-probe-only=true", target},
-               &bytes.Buffer{}, &bytes.Buffer{}, stderr)
+               &bytes.Buffer{}, &probetarget, stderr)
        if exitcode != 0 {
                return exitcode
        }
+       target = strings.Trim(probetarget.String(), "\n")
 
        selfbin, err := os.Readlink("/proc/self/exe")
        if err != nil {
@@ -119,7 +125,7 @@ Options:
 `)
                f.PrintDefaults()
        }
-       probeOnly := f.Bool("probe-only", false, "do not transfer IO, just exit 0 immediately if tunnel setup succeeds")
+       probeOnly := f.Bool("probe-only", false, "do not transfer IO, just setup tunnel, print target UUID, and exit")
        detachKeys := f.String("detach-keys", "", "set detach key sequence, as in docker-attach(1)")
        if err := f.Parse(args); err != nil {
                fmt.Fprintln(stderr, err)
@@ -181,6 +187,7 @@ Options:
        defer sshconn.Conn.Close()
 
        if *probeOnly {
+               fmt.Fprintln(stdout, targetUUID)
                return 0
        }