open-nomad/command/monitor.go
2016-01-20 00:02:17 +01:00

362 lines
10 KiB
Go

package command
import (
"fmt"
"sync"
"time"
"github.com/hashicorp/nomad/api"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/mitchellh/cli"
)
const (
// updateWait is the amount of time to wait between status
// updates. Because the monitor is poll-based, we use this
// delay to avoid overwhelming the API server.
updateWait = time.Second
)
// evalState is used to store the current "state of the world"
// in the context of monitoring an evaluation.
type evalState struct {
status string
desc string
node string
job string
allocs map[string]*allocState
wait time.Duration
index uint64
}
// newEvalState creates and initializes a new monitorState
func newEvalState() *evalState {
return &evalState{
status: structs.EvalStatusPending,
allocs: make(map[string]*allocState),
}
}
// allocState is used to track the state of an allocation
type allocState struct {
id string
group string
node string
desired string
desiredDesc string
client string
clientDesc string
index uint64
// full is the allocation struct with full details. This
// must be queried for explicitly so it is only included
// if there is important error information inside.
full *api.Allocation
}
// monitor wraps an evaluation monitor and holds metadata and
// state information.
type monitor struct {
ui cli.Ui
client *api.Client
state *evalState
// length determines the number of characters for identifiers in the ui.
length int
sync.Mutex
}
// newMonitor returns a new monitor. The returned monitor will
// write output information to the provided ui. The length parameter determines
// the number of characters for identifiers in the ui.
func newMonitor(ui cli.Ui, client *api.Client, length int) *monitor {
mon := &monitor{
ui: &cli.PrefixedUi{
InfoPrefix: "==> ",
OutputPrefix: " ",
ErrorPrefix: "==> ",
Ui: ui,
},
client: client,
state: newEvalState(),
length: length,
}
return mon
}
// update is used to update our monitor with new state. It can be
// called whether the passed information is new or not, and will
// only dump update messages when state changes.
func (m *monitor) update(update *evalState) {
m.Lock()
defer m.Unlock()
existing := m.state
// Swap in the new state at the end
defer func() {
m.state = update
}()
// Check if the evaluation was triggered by a node
if existing.node == "" && update.node != "" {
m.ui.Output(fmt.Sprintf("Evaluation triggered by node %q",
update.node[:m.length]))
}
// Check if the evaluation was triggered by a job
if existing.job == "" && update.job != "" {
m.ui.Output(fmt.Sprintf("Evaluation triggered by job %q", update.job))
}
// Check the allocations
for allocID, alloc := range update.allocs {
if existing, ok := existing.allocs[allocID]; !ok {
switch {
case alloc.desired == structs.AllocDesiredStatusFailed:
// New allocs with desired state failed indicate
// scheduling failure.
m.ui.Output(fmt.Sprintf("Scheduling error for group %q (%s)",
alloc.group, alloc.desiredDesc))
// Log the client status, if any provided
if alloc.clientDesc != "" {
m.ui.Output("Client reported status: " + alloc.clientDesc)
}
// Generate a more descriptive error for why the allocation
// failed and dump it to the screen
if alloc.full != nil {
dumpAllocStatus(m.ui, alloc.full, m.length)
}
case alloc.index < update.index:
// New alloc with create index lower than the eval
// create index indicates modification
m.ui.Output(fmt.Sprintf(
"Allocation %q modified: node %q, group %q",
alloc.id[:m.length], alloc.node[:m.length], alloc.group))
case alloc.desired == structs.AllocDesiredStatusRun:
// New allocation with desired status running
m.ui.Output(fmt.Sprintf(
"Allocation %q created: node %q, group %q",
alloc.id[:m.length], alloc.node[:m.length], alloc.group))
}
} else {
switch {
case existing.client != alloc.client:
// Allocation status has changed
m.ui.Output(fmt.Sprintf(
"Allocation %q status changed: %q -> %q (%s)",
alloc.id[:m.length], existing.client, alloc.client, alloc.clientDesc))
}
}
}
// Check if the status changed. We skip any transitions to pending status.
if existing.status != "" &&
update.status != structs.AllocClientStatusPending &&
existing.status != update.status {
m.ui.Output(fmt.Sprintf("Evaluation status changed: %q -> %q",
existing.status, update.status))
}
}
// monitor is used to start monitoring the given evaluation ID. It
// writes output directly to the monitor's ui, and returns the
// exit code for the command. If allowPrefix is false, monitor will only accept
// exact matching evalIDs.
//
// The return code will be 0 on successful evaluation. If there are
// problems scheduling the job (impossible constraints, resources
// exhausted, etc), then the return code will be 2. For any other
// failures (API connectivity, internal errors, etc), the return code
// will be 1.
func (m *monitor) monitor(evalID string, allowPrefix bool) int {
// Track if we encounter a scheduling failure. This can only be
// detected while querying allocations, so we use this bool to
// carry that status into the return code.
var schedFailure bool
// The user may have specified a prefix as eval id. We need to lookup the
// full id from the database first. Since we do this in a loop we need a
// variable to keep track if we've already written the header message.
var headerWritten bool
// Add the initial pending state
m.update(newEvalState())
for {
// Query the evaluation
eval, _, err := m.client.Evaluations().Info(evalID, nil)
if err != nil {
if !allowPrefix {
m.ui.Error(fmt.Sprintf("No evaluation with id %q found", evalID))
return 1
}
evals, _, err := m.client.Evaluations().PrefixList(evalID)
if err != nil {
m.ui.Error(fmt.Sprintf("Error reading evaluation: %s", err))
return 1
}
if len(evals) == 0 {
m.ui.Error(fmt.Sprintf("No evaluation(s) with prefix or id %q found", evalID))
return 1
}
if len(evals) > 1 {
// Format the evaluations
out := make([]string, len(evals)+1)
out[0] = "ID|Priority|Type|TriggeredBy|Status"
for i, eval := range evals {
out[i+1] = fmt.Sprintf("%s|%d|%s|%s|%s",
eval.ID[:m.length],
eval.Priority,
eval.Type,
eval.TriggeredBy,
eval.Status)
}
m.ui.Output(fmt.Sprintf("Prefix matched multiple evaluations\n\n%s", formatList(out)))
return 0
}
// Prefix lookup matched a single evaluation
eval, _, err = m.client.Evaluations().Info(evals[0].ID, nil)
if err != nil {
m.ui.Error(fmt.Sprintf("Error reading evaluation: %s", err))
}
}
if !headerWritten {
m.ui.Info(fmt.Sprintf("Monitoring evaluation %q", eval.ID[:m.length]))
headerWritten = true
}
// Create the new eval state.
state := newEvalState()
state.status = eval.Status
state.desc = eval.StatusDescription
state.node = eval.NodeID
state.job = eval.JobID
state.wait = eval.Wait
state.index = eval.CreateIndex
// Query the allocations associated with the evaluation
allocs, _, err := m.client.Evaluations().Allocations(eval.ID, nil)
if err != nil {
m.ui.Error(fmt.Sprintf("Error reading allocations: %s", err))
return 1
}
// Add the allocs to the state
for _, alloc := range allocs {
state.allocs[alloc.ID] = &allocState{
id: alloc.ID,
group: alloc.TaskGroup,
node: alloc.NodeID,
desired: alloc.DesiredStatus,
desiredDesc: alloc.DesiredDescription,
client: alloc.ClientStatus,
clientDesc: alloc.ClientDescription,
index: alloc.CreateIndex,
}
// If we have a scheduling error, query the full allocation
// to get the details.
if alloc.DesiredStatus == structs.AllocDesiredStatusFailed {
schedFailure = true
failed, _, err := m.client.Allocations().Info(alloc.ID, nil)
if err != nil {
m.ui.Error(fmt.Sprintf("Error querying allocation: %s", err))
return 1
}
state.allocs[alloc.ID].full = failed
}
}
// Update the state
m.update(state)
switch eval.Status {
case structs.EvalStatusComplete, structs.EvalStatusFailed:
m.ui.Info(fmt.Sprintf("Evaluation %q finished with status %q",
eval.ID[:m.length], eval.Status))
default:
// Wait for the next update
time.Sleep(updateWait)
continue
}
// Monitor the next eval in the chain, if present
if eval.NextEval != "" {
m.ui.Info(fmt.Sprintf(
"Monitoring next evaluation %q in %s",
eval.NextEval, eval.Wait))
// Skip some unnecessary polling
time.Sleep(eval.Wait)
// Reset the state and monitor the new eval
m.state = newEvalState()
return m.monitor(eval.NextEval, allowPrefix)
}
break
}
// Treat scheduling failures specially using a dedicated exit code.
// This makes it easier to detect failures from the CLI.
if schedFailure {
return 2
}
return 0
}
// dumpAllocStatus is a helper to generate a more user-friendly error message
// for scheduling failures, displaying a high level status of why the job
// could not be scheduled out.
func dumpAllocStatus(ui cli.Ui, alloc *api.Allocation, length int) {
// Print filter stats
ui.Output(fmt.Sprintf("Allocation %q status %q (%d/%d nodes filtered)",
alloc.ID[:length], alloc.ClientStatus,
alloc.Metrics.NodesFiltered, alloc.Metrics.NodesEvaluated))
// Print a helpful message if we have an eligibility problem
if alloc.Metrics.NodesEvaluated == 0 {
ui.Output(" * No nodes were eligible for evaluation")
}
// Print a helpful message if the user has asked for a DC that has no
// available nodes.
for dc, available := range alloc.Metrics.NodesAvailable {
if available == 0 {
ui.Output(fmt.Sprintf(" * No nodes are available in datacenter %q", dc))
}
}
// Print filter info
for class, num := range alloc.Metrics.ClassFiltered {
ui.Output(fmt.Sprintf(" * Class %q filtered %d nodes", class, num))
}
for cs, num := range alloc.Metrics.ConstraintFiltered {
ui.Output(fmt.Sprintf(" * Constraint %q filtered %d nodes", cs, num))
}
// Print exhaustion info
if ne := alloc.Metrics.NodesExhausted; ne > 0 {
ui.Output(fmt.Sprintf(" * Resources exhausted on %d nodes", ne))
}
for class, num := range alloc.Metrics.ClassExhausted {
ui.Output(fmt.Sprintf(" * Class %q exhausted on %d nodes", class, num))
}
for dim, num := range alloc.Metrics.DimensionExhausted {
ui.Output(fmt.Sprintf(" * Dimension %q exhausted on %d nodes", dim, num))
}
// Print scores
for name, score := range alloc.Metrics.Scores {
ui.Output(fmt.Sprintf(" * Score %q = %f", name, score))
}
}