open-nomad/client/allocrunner/taskrunner/identity_hook.go

93 lines
2.1 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package taskrunner
import (
"context"
"fmt"
"path/filepath"
"sync"
log "github.com/hashicorp/go-hclog"
"github.com/hashicorp/nomad/client/allocrunner/interfaces"
"github.com/hashicorp/nomad/helper/users"
)
// identityHook sets the task runner's Nomad workload identity token
// based on the signed identity stored on the Allocation
const (
// wiTokenFile is the name of the file holding the Nomad token inside the
// task's secret directory
wiTokenFile = "nomad_token"
)
type identityHook struct {
tr *TaskRunner
logger log.Logger
taskName string
lock sync.Mutex
// tokenPath is the path in which to read and write the token
tokenPath string
}
func newIdentityHook(tr *TaskRunner, logger log.Logger) *identityHook {
h := &identityHook{
tr: tr,
taskName: tr.taskName,
}
h.logger = logger.Named(h.Name())
return h
}
func (*identityHook) Name() string {
return "identity"
}
func (h *identityHook) Prestart(ctx context.Context, req *interfaces.TaskPrestartRequest, resp *interfaces.TaskPrestartResponse) error {
h.lock.Lock()
defer h.lock.Unlock()
h.tokenPath = filepath.Join(req.TaskDir.SecretsDir, wiTokenFile)
return h.setToken()
}
func (h *identityHook) Update(_ context.Context, req *interfaces.TaskUpdateRequest, _ *interfaces.TaskUpdateResponse) error {
h.lock.Lock()
defer h.lock.Unlock()
return h.setToken()
}
// setToken adds the Nomad token to the task's environment and writes it to a
// file if requested by the jobsepc.
func (h *identityHook) setToken() error {
token := h.tr.alloc.SignedIdentities[h.taskName]
if token == "" {
return nil
}
h.tr.setNomadToken(token)
if id := h.tr.task.Identity; id != nil && id.File {
if err := h.writeToken(token); err != nil {
return err
}
}
return nil
}
// writeToken writes the given token to disk
func (h *identityHook) writeToken(token string) error {
// Write token as owner readable only
if err := users.WriteFileFor(h.tokenPath, []byte(token), h.tr.task.User); err != nil {
return fmt.Errorf("failed to write nomad token: %w", err)
}
return nil
}