open-nomad/command/node_drain.go

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// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package command
import (
"context"
"fmt"
"strings"
"time"
"github.com/hashicorp/nomad/api"
"github.com/hashicorp/nomad/api/contexts"
flaghelper "github.com/hashicorp/nomad/helper/flags"
"github.com/posener/complete"
)
var (
// defaultDrainDuration is the default drain duration if it is not specified
// explicitly
defaultDrainDuration = 1 * time.Hour
)
type NodeDrainCommand struct {
Meta
}
func (c *NodeDrainCommand) Help() string {
helpText := `
Usage: nomad node drain [options] <node>
Toggles node draining on a specified node. It is required that either
-enable or -disable is specified, but not both. The -self flag is useful to
drain the local node.
If ACLs are enabled, this option requires a token with the 'node:write'
capability.
General Options:
` + generalOptionsUsage(usageOptsDefault|usageOptsNoNamespace) + `
Node Drain Options:
-disable
Disable draining for the specified node.
-enable
Enable draining for the specified node.
-deadline <duration>
Set the deadline by which all allocations must be moved off the node.
Remaining allocations after the deadline are forced removed from the node.
If unspecified, a default deadline of one hour is applied.
-detach
Return immediately instead of entering monitor mode.
-monitor
Enter monitor mode directly without modifying the drain status.
-force
Force remove allocations off the node immediately.
-no-deadline
No deadline allows the allocations to drain off the node without being force
stopped after a certain deadline.
-ignore-system
Ignore system allows the drain to complete without stopping system job
allocations. By default system jobs are stopped last.
-keep-ineligible
Keep ineligible will maintain the node's scheduling ineligibility even if
the drain is being disabled. This is useful when an existing drain is being
cancelled but additional scheduling on the node is not desired.
-m
Message for the drain update operation. Registered in drain metadata as
"message" during drain enable and "cancel_message" during drain disable.
-meta <key>=<value>
Custom metadata to store on the drain operation, can be used multiple times.
-self
Set the drain status of the local node.
-yes
Automatic yes to prompts.
`
return strings.TrimSpace(helpText)
}
func (c *NodeDrainCommand) Synopsis() string {
return "Toggle drain mode on a given node"
}
func (c *NodeDrainCommand) AutocompleteFlags() complete.Flags {
return mergeAutocompleteFlags(c.Meta.AutocompleteFlags(FlagSetClient),
complete.Flags{
"-disable": complete.PredictNothing,
"-enable": complete.PredictNothing,
"-deadline": complete.PredictAnything,
"-detach": complete.PredictNothing,
"-force": complete.PredictNothing,
"-no-deadline": complete.PredictNothing,
"-ignore-system": complete.PredictNothing,
"-keep-ineligible": complete.PredictNothing,
"-m": complete.PredictNothing,
"-meta": complete.PredictNothing,
"-self": complete.PredictNothing,
"-yes": complete.PredictNothing,
})
}
func (c *NodeDrainCommand) AutocompleteArgs() complete.Predictor {
return complete.PredictFunc(func(a complete.Args) []string {
client, err := c.Meta.Client()
if err != nil {
return nil
}
resp, _, err := client.Search().PrefixSearch(a.Last, contexts.Nodes, nil)
if err != nil {
return []string{}
}
return resp.Matches[contexts.Nodes]
})
}
func (c *NodeDrainCommand) Name() string { return "node drain" }
func (c *NodeDrainCommand) Run(args []string) int {
var enable, disable, detach, force,
noDeadline, ignoreSystem, keepIneligible,
self, autoYes, monitor bool
var deadline, message string
var metaVars flaghelper.StringFlag
flags := c.Meta.FlagSet(c.Name(), FlagSetClient)
flags.Usage = func() { c.Ui.Output(c.Help()) }
flags.BoolVar(&enable, "enable", false, "Enable drain mode")
flags.BoolVar(&disable, "disable", false, "Disable drain mode")
flags.StringVar(&deadline, "deadline", "", "Deadline after which allocations are force stopped")
flags.BoolVar(&detach, "detach", false, "")
flags.BoolVar(&force, "force", false, "Force immediate drain")
flags.BoolVar(&noDeadline, "no-deadline", false, "Drain node with no deadline")
flags.BoolVar(&ignoreSystem, "ignore-system", false, "Do not drain system job allocations from the node")
flags.BoolVar(&keepIneligible, "keep-ineligible", false, "Do not update the nodes scheduling eligibility")
flags.BoolVar(&self, "self", false, "")
flags.BoolVar(&autoYes, "yes", false, "Automatic yes to prompts.")
flags.BoolVar(&monitor, "monitor", false, "Monitor drain status.")
flags.StringVar(&message, "m", "", "Drain message")
flags.Var(&metaVars, "meta", "Drain metadata")
if err := flags.Parse(args); err != nil {
return 1
}
// Check that enable or disable is not set with monitor
if monitor && (enable || disable) {
c.Ui.Error("The -monitor flag cannot be used with the '-enable' or '-disable' flags")
c.Ui.Error(commandErrorText(c))
return 1
}
// Check that we got either enable or disable, but not both.
if (enable && disable) || (!monitor && !enable && !disable) {
c.Ui.Error("Either the '-enable' or '-disable' flag must be set, unless using '-monitor'")
c.Ui.Error(commandErrorText(c))
return 1
}
// Check that we got a node ID
args = flags.Args()
if l := len(args); self && l != 0 || !self && l != 1 {
c.Ui.Error("Node ID must be specified if -self isn't being used")
c.Ui.Error(commandErrorText(c))
return 1
}
// Validate a compatible set of flags were set
if disable && (deadline != "" || force || noDeadline || ignoreSystem) {
c.Ui.Error("-disable can't be combined with flags configuring drain strategy")
c.Ui.Error(commandErrorText(c))
return 1
}
if deadline != "" && (force || noDeadline) {
c.Ui.Error("-deadline can't be combined with -force or -no-deadline")
c.Ui.Error(commandErrorText(c))
return 1
}
if force && noDeadline {
c.Ui.Error("-force and -no-deadline are mutually exclusive")
c.Ui.Error(commandErrorText(c))
return 1
}
// Parse the duration
var d time.Duration
if force {
d = -1 * time.Second
} else if noDeadline {
d = 0
} else if deadline != "" {
dur, err := time.ParseDuration(deadline)
if err != nil {
c.Ui.Error(fmt.Sprintf("Failed to parse deadline %q: %v", deadline, err))
return 1
}
if dur <= 0 {
c.Ui.Error("A positive drain duration must be given")
return 1
}
d = dur
} else {
d = defaultDrainDuration
}
// Get the HTTP client
client, err := c.Meta.Client()
if err != nil {
c.Ui.Error(fmt.Sprintf("Error initializing client: %s", err))
return 1
}
// If -self flag is set then determine the current node.
var nodeID string
if !self {
nodeID = args[0]
} else {
var err error
if nodeID, err = getLocalNodeID(client); err != nil {
c.Ui.Error(err.Error())
return 1
}
}
// Check if node exists
if len(nodeID) == 1 {
c.Ui.Error("Identifier must contain at least two characters.")
return 1
}
nodeID = sanitizeUUIDPrefix(nodeID)
nodes, _, err := client.Nodes().PrefixList(nodeID)
if err != nil {
c.Ui.Error(fmt.Sprintf("Error toggling drain mode: %s", err))
return 1
}
// Return error if no nodes are found
if len(nodes) == 0 {
c.Ui.Error(fmt.Sprintf("No node(s) with prefix or id %q found", nodeID))
return 1
}
if len(nodes) > 1 {
c.Ui.Error(fmt.Sprintf("Prefix matched multiple nodes\n\n%s",
formatNodeStubList(nodes, true)))
return 1
}
// Prefix lookup matched a single node
node, meta, err := client.Nodes().Info(nodes[0].ID, nil)
if err != nil {
c.Ui.Error(fmt.Sprintf("Error toggling drain mode: %s", err))
return 1
}
// If monitoring the drain start the monitor and return when done
if monitor {
if node.DrainStrategy == nil {
c.Ui.Warn("No drain strategy set")
return 0
}
c.Ui.Info(fmt.Sprintf("%s: Monitoring node %q: Ctrl-C to detach monitoring", formatTime(time.Now()), node.ID))
c.monitorDrain(client, context.Background(), node, meta.LastIndex, ignoreSystem)
return 0
}
// Confirm drain if the node was a prefix match.
if nodeID != node.ID && !autoYes {
verb := "enable"
if disable {
verb = "disable"
}
question := fmt.Sprintf("Are you sure you want to %s drain mode for node %q? [y/N]", verb, node.ID)
answer, err := c.Ui.Ask(question)
if err != nil {
c.Ui.Error(fmt.Sprintf("Failed to parse answer: %v", err))
return 1
}
if answer == "" || strings.ToLower(answer)[0] == 'n' {
// No case
c.Ui.Output("Canceling drain toggle")
return 0
} else if strings.ToLower(answer)[0] == 'y' && len(answer) > 1 {
// Non exact match yes
c.Ui.Output("For confirmation, an exact y is required.")
return 0
} else if answer != "y" {
c.Ui.Output("No confirmation detected. For confirmation, an exact 'y' is required.")
return 1
}
}
var spec *api.DrainSpec
if enable {
spec = &api.DrainSpec{
Deadline: d,
IgnoreSystemJobs: ignoreSystem,
}
}
// propagate drain metadata if cancelling
drainMeta := make(map[string]string)
if disable && node.LastDrain != nil && node.LastDrain.Meta != nil {
drainMeta = node.LastDrain.Meta
}
if message != "" {
if enable {
drainMeta["message"] = message
} else {
drainMeta["cancel_message"] = message
}
}
for _, m := range metaVars {
if len(m) == 0 {
continue
}
kv := strings.SplitN(m, "=", 2)
if len(kv) == 2 {
drainMeta[kv[0]] = kv[1]
} else {
drainMeta[kv[0]] = ""
}
}
// Toggle node draining
drainResponse, err := client.Nodes().UpdateDrainOpts(node.ID,
&api.DrainOptions{
DrainSpec: spec,
MarkEligible: !keepIneligible,
Meta: drainMeta,
}, nil)
if err != nil {
c.Ui.Error(fmt.Sprintf("Error updating drain specification: %s", err))
return 1
}
if !enable || detach {
if enable {
c.Ui.Output(fmt.Sprintf("Node %q drain strategy set", node.ID))
} else {
c.Ui.Output(fmt.Sprintf("Node %q drain strategy unset", node.ID))
}
}
if enable && !detach {
now := time.Now()
c.Ui.Info(fmt.Sprintf("%s: Ctrl-C to stop monitoring: will not cancel the node drain", formatTime(now)))
c.Ui.Output(fmt.Sprintf("%s: Node %q drain strategy set", formatTime(now), node.ID))
c.monitorDrain(client, context.Background(), node, drainResponse.LastIndex, ignoreSystem)
}
return 0
}
func (c *NodeDrainCommand) monitorDrain(client *api.Client, ctx context.Context, node *api.Node, index uint64, ignoreSystem bool) {
outCh := client.Nodes().MonitorDrain(ctx, node.ID, index, ignoreSystem)
for msg := range outCh {
switch msg.Level {
case api.MonitorMsgLevelInfo:
c.Ui.Info(fmt.Sprintf("%s: %s", formatTime(time.Now()), msg))
case api.MonitorMsgLevelWarn:
c.Ui.Warn(fmt.Sprintf("%s: %s", formatTime(time.Now()), msg))
case api.MonitorMsgLevelError:
c.Ui.Error(fmt.Sprintf("%s: %s", formatTime(time.Now()), msg))
default:
c.Ui.Output(fmt.Sprintf("%s: %s", formatTime(time.Now()), msg))
}
}
}