package command
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import (
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"flag"
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"fmt"
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"strings"
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"github.com/mitchellh/cli"
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)
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// RTTCommand is a Command implementation that allows users to query the
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// estimated round trip time between nodes using network coordinates.
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type RTTCommand struct {
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Ui cli.Ui
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}
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func (c *RTTCommand) Help() string {
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helpText := `
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Usage: serf rtt [options] node1 [node2]
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Estimates the round trip time between two nodes using Serf's network
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coordinate model of the cluster.
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At least one node name is required. If the second node name isn't given, it
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is set to the agent's node name. Note that these are node names as known to
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Serf as "serf members" would show, not IP addresses.
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Options:
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-rpc-addr=127.0.0.1:7373 RPC address of the Serf agent.
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-rpc-auth="" RPC auth token of the Serf agent.
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`
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return strings.TrimSpace(helpText)
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}
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func (c *RTTCommand) Run(args []string) int {
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cmdFlags := flag.NewFlagSet("rtt", flag.ContinueOnError)
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cmdFlags.Usage = func() { c.Ui.Output(c.Help()) }
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rpcAddr := RPCAddrFlag(cmdFlags)
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rpcAuth := RPCAuthFlag(cmdFlags)
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if err := cmdFlags.Parse(args); err != nil {
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return 1
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}
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// Create the RPC client.
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client, err := RPCClient(*rpcAddr, *rpcAuth)
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if err != nil {
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c.Ui.Error(fmt.Sprintf("Error connecting to Serf agent: %s", err))
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return 1
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}
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defer client.Close()
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// They must provide at least one node.
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nodes := cmdFlags.Args()
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if len(nodes) == 1 {
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stats, err := client.Stats()
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if err != nil {
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c.Ui.Error(fmt.Sprintf("Error querying agent: %s", err))
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return 1
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}
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nodes = append(nodes, stats["agent"]["name"])
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} else if len(nodes) != 2 {
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c.Ui.Error("One or two node names must be specified")
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c.Ui.Error("")
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c.Ui.Error(c.Help())
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return 1
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}
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// Get the coordinates.
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coord1, err := client.GetCoordinate(nodes[0])
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if err != nil {
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c.Ui.Error(fmt.Sprintf("Error getting coordinates: %s", err))
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return 1
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}
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if coord1 == nil {
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c.Ui.Error(fmt.Sprintf("Could not find a coordinate for node %q", nodes[0]))
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return 1
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}
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coord2, err := client.GetCoordinate(nodes[1])
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if err != nil {
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c.Ui.Error(fmt.Sprintf("Error getting coordinates: %s", err))
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return 1
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}
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if coord2 == nil {
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c.Ui.Error(fmt.Sprintf("Could not find a coordinate for node %q", nodes[1]))
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return 1
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}
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// Report the round trip time.
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dist := fmt.Sprintf("%.3f ms", coord1.DistanceTo(coord2).Seconds()*1000.0)
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c.Ui.Output(fmt.Sprintf("Estimated %s <-> %s rtt: %s", nodes[0], nodes[1], dist))
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return 0
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}
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func (c *RTTCommand) Synopsis() string {
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return "Estimates network round trip time between nodes"
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}
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