open-nomad/client/allocrunner/taskrunner/envoy_bootstrap_hook.go
Seth Hoenig 238ac718f2 connect: use exp backoff when waiting on consul envoy bootstrap
This PR wraps the use of the consul envoy bootstrap command in
an expoenential backoff closure, configured to timeout after 60
seconds. This is an increase over the current behavior of making
3 attempts over 6 seconds.

Should help with #10451
2021-04-27 09:21:50 -06:00

551 lines
17 KiB
Go

package taskrunner
import (
"bytes"
"context"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"time"
"github.com/hashicorp/go-hclog"
"github.com/hashicorp/nomad/client/allocdir"
ifs "github.com/hashicorp/nomad/client/allocrunner/interfaces"
"github.com/hashicorp/nomad/client/taskenv"
agentconsul "github.com/hashicorp/nomad/command/agent/consul"
"github.com/hashicorp/nomad/helper"
"github.com/hashicorp/nomad/helper/exptime"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/hashicorp/nomad/nomad/structs/config"
"github.com/pkg/errors"
)
const envoyBootstrapHookName = "envoy_bootstrap"
const (
// envoyBootstrapWaitTime is the amount of time this hook should wait on Consul
// objects to be created before giving up.
envoyBootstrapWaitTime = 60 * time.Second
// envoyBootstrapInitialGap is the initial amount of time the envoy bootstrap
// retry loop will wait, exponentially increasing each iteration, not including
// jitter.
envoyBoostrapInitialGap = 1 * time.Second
// envoyBootstrapMaxJitter is the maximum amount of jitter applied to the
// wait gap each iteration of the envoy bootstrap retry loop.
envoyBootstrapMaxJitter = 500 * time.Millisecond
)
type consulTransportConfig struct {
HTTPAddr string // required
Auth string // optional, env CONSUL_HTTP_AUTH
SSL string // optional, env CONSUL_HTTP_SSL
VerifySSL string // optional, env CONSUL_HTTP_SSL_VERIFY
CAFile string // optional, arg -ca-file
CertFile string // optional, arg -client-cert
KeyFile string // optional, arg -client-key
Namespace string // optional, only consul Enterprise, env CONSUL_NAMESPACE
// CAPath (dir) not supported by Nomad's config object
}
func newConsulTransportConfig(consul *config.ConsulConfig) consulTransportConfig {
return consulTransportConfig{
HTTPAddr: consul.Addr,
Auth: consul.Auth,
SSL: decodeTriState(consul.EnableSSL),
VerifySSL: decodeTriState(consul.VerifySSL),
CAFile: consul.CAFile,
CertFile: consul.CertFile,
KeyFile: consul.KeyFile,
Namespace: consul.Namespace,
}
}
type envoyBootstrapHookConfig struct {
alloc *structs.Allocation
consul consulTransportConfig
consulNamespace string
logger hclog.Logger
}
func decodeTriState(b *bool) string {
switch {
case b == nil:
return ""
case *b:
return "true"
default:
return "false"
}
}
func newEnvoyBootstrapHookConfig(alloc *structs.Allocation, consul *config.ConsulConfig, consulNamespace string, logger hclog.Logger) *envoyBootstrapHookConfig {
return &envoyBootstrapHookConfig{
alloc: alloc,
consul: newConsulTransportConfig(consul),
consulNamespace: consulNamespace,
logger: logger,
}
}
const (
envoyBaseAdminPort = 19000
envoyAdminBindEnvPrefix = "NOMAD_ENVOY_ADMIN_ADDR_"
)
const (
grpcConsulVariable = "CONSUL_GRPC_ADDR"
grpcDefaultAddress = "127.0.0.1:8502"
)
// envoyBootstrapHook writes the bootstrap config for the Connect Envoy proxy
// sidecar.
type envoyBootstrapHook struct {
// alloc is the allocation with the envoy task being bootstrapped.
alloc *structs.Allocation
// Bootstrapping Envoy requires talking directly to Consul to generate
// the bootstrap.json config. Runtime Envoy configuration is done via
// Consul's gRPC endpoint. There are many security parameters to configure
// before contacting Consul.
consulConfig consulTransportConfig
// consulNamespace is the Consul namespace as set by in the job
consulNamespace string
// envoyBootstrapWaitTime is the total amount of time hook will wait for Consul
envoyBootstrapWaitTime time.Duration
// envoyBootstrapInitialGap is the initial wait gap when retyring
envoyBoostrapInitialGap time.Duration
// envoyBootstrapMaxJitter is the maximum amount of jitter applied to retries
envoyBootstrapMaxJitter time.Duration
// envoyBootstrapExpSleep controls exponential waiting
envoyBootstrapExpSleep func(time.Duration)
// logger is used to log things
logger hclog.Logger
}
func newEnvoyBootstrapHook(c *envoyBootstrapHookConfig) *envoyBootstrapHook {
return &envoyBootstrapHook{
alloc: c.alloc,
consulConfig: c.consul,
consulNamespace: c.consulNamespace,
envoyBootstrapWaitTime: envoyBootstrapWaitTime,
envoyBoostrapInitialGap: envoyBoostrapInitialGap,
envoyBootstrapMaxJitter: envoyBootstrapMaxJitter,
envoyBootstrapExpSleep: time.Sleep,
logger: c.logger.Named(envoyBootstrapHookName),
}
}
// getConsulNamespace will resolve the Consul namespace, choosing between
// - agent config (low precedence)
// - task group config (high precedence)
func (h *envoyBootstrapHook) getConsulNamespace() string {
var namespace string
if h.consulConfig.Namespace != "" {
namespace = h.consulConfig.Namespace
}
if h.consulNamespace != "" {
namespace = h.consulNamespace
}
return namespace
}
func (envoyBootstrapHook) Name() string {
return envoyBootstrapHookName
}
func isConnectKind(kind string) bool {
kinds := []string{structs.ConnectProxyPrefix, structs.ConnectIngressPrefix, structs.ConnectTerminatingPrefix}
return helper.SliceStringContains(kinds, kind)
}
func (_ *envoyBootstrapHook) extractNameAndKind(kind structs.TaskKind) (string, string, error) {
serviceName := kind.Value()
serviceKind := kind.Name()
if !isConnectKind(serviceKind) {
return "", "", errors.New("envoy must be used as connect sidecar or gateway")
}
if serviceName == "" {
return "", "", errors.New("envoy must be configured with a service name")
}
return serviceKind, serviceName, nil
}
func (h *envoyBootstrapHook) lookupService(svcKind, svcName, tgName string, taskEnv *taskenv.TaskEnv) (*structs.Service, error) {
tg := h.alloc.Job.LookupTaskGroup(h.alloc.TaskGroup)
interpolatedServices := taskenv.InterpolateServices(taskEnv, tg.Services)
var service *structs.Service
for _, s := range interpolatedServices {
if s.Name == svcName {
service = s
break
}
}
if service == nil {
if svcKind == structs.ConnectProxyPrefix {
return nil, errors.New("connect proxy sidecar task exists but no services configured with a sidecar")
} else {
return nil, errors.New("connect gateway task exists but no service associated")
}
}
return service, nil
}
// Prestart creates an envoy bootstrap config file.
//
// Must be aware of both launching envoy as a sidecar proxy, as well as a connect gateway.
func (h *envoyBootstrapHook) Prestart(ctx context.Context, req *ifs.TaskPrestartRequest, resp *ifs.TaskPrestartResponse) error {
if !req.Task.Kind.IsConnectProxy() && !req.Task.Kind.IsAnyConnectGateway() {
// Not a Connect proxy sidecar
resp.Done = true
return nil
}
serviceKind, serviceName, err := h.extractNameAndKind(req.Task.Kind)
if err != nil {
return err
}
service, err := h.lookupService(serviceKind, serviceName, h.alloc.TaskGroup, req.TaskEnv)
if err != nil {
return err
}
grpcAddr := h.grpcAddress(req.TaskEnv.EnvMap)
h.logger.Debug("bootstrapping Consul "+serviceKind, "task", req.Task.Name, "service", serviceName)
// Envoy runs an administrative API on the loopback interface. There is no
// way to turn this feature off.
// https://github.com/envoyproxy/envoy/issues/1297
envoyAdminBind := buildEnvoyAdminBind(h.alloc, serviceName, req.Task.Name, req.TaskEnv)
resp.Env = map[string]string{
helper.CleanEnvVar(envoyAdminBindEnvPrefix+serviceName, '_'): envoyAdminBind,
}
// Envoy bootstrap configuration may contain a Consul token, so write
// it to the secrets directory like Vault tokens.
bootstrapFilePath := filepath.Join(req.TaskDir.SecretsDir, "envoy_bootstrap.json")
siToken, err := h.maybeLoadSIToken(req.Task.Name, req.TaskDir.SecretsDir)
if err != nil {
h.logger.Error("failed to generate envoy bootstrap config", "sidecar_for", service.Name)
return errors.Wrap(err, "failed to generate envoy bootstrap config")
}
h.logger.Debug("check for SI token for task", "task", req.Task.Name, "exists", siToken != "")
bootstrap := h.newEnvoyBootstrapArgs(h.alloc.TaskGroup, service, grpcAddr, envoyAdminBind, siToken, bootstrapFilePath)
bootstrapArgs := bootstrap.args()
bootstrapEnv := bootstrap.env(os.Environ())
// keep track of latest error returned from exec-ing consul envoy bootstrap
var cmdErr error
// Since Consul services are registered asynchronously with this task
// hook running, retry until timeout or success.
if backoffErr := exptime.Backoff(func() (bool, error) {
// If hook is killed, just stop.
select {
case <-ctx.Done():
return false, nil
default:
}
// Prepare bootstrap command to run.
cmd := exec.CommandContext(ctx, "consul", bootstrapArgs...)
cmd.Env = bootstrapEnv
// Redirect stdout to secrets/envoy_bootstrap.json.
fd, fileErr := os.Create(bootstrapFilePath)
if fileErr != nil {
return false, fmt.Errorf("failed to create secrets/envoy_bootstrap.json for envoy: %w", fileErr)
}
cmd.Stdout = fd
// Redirect stderr into a buffer for later reading.
buf := bytes.NewBuffer(nil)
cmd.Stderr = buf
// Generate bootstrap
cmdErr = cmd.Run()
// Close bootstrap.json regardless of any command errors.
_ = fd.Close()
// Command succeeded, exit.
if cmdErr == nil {
// Bootstrap written. Mark as done and move on.
resp.Done = true
return false, nil
}
// Command failed, prepare for retry
//
// Cleanup the bootstrap file. An errors here is not
// important as (a) we test to ensure the deletion
// occurs, and (b) the file will either be rewritten on
// retry or eventually garbage collected if the task
// fails.
_ = os.Remove(bootstrapFilePath)
return true, cmdErr
}, exptime.BackoffOptions{
MaxSleepTime: h.envoyBootstrapWaitTime,
InitialGapSize: h.envoyBoostrapInitialGap,
MaxJitterSize: h.envoyBootstrapMaxJitter,
}); backoffErr != nil {
// Wrap the last error from Consul and set that as our status.
_, recoverable := cmdErr.(*exec.ExitError)
return structs.NewRecoverableError(
fmt.Errorf("error creating bootstrap configuration for Connect proxy sidecar: %v", cmdErr),
recoverable,
)
}
return nil
}
// buildEnvoyAdminBind determines a unique port for use by the envoy admin
// listener.
//
// In bridge mode, if multiple sidecars are running, the bind addresses need
// to be unique within the namespace, so we simply start at 19000 and increment
// by the index of the task.
//
// In host mode, use the port provided through the service definition, which can
// be a port chosen by Nomad.
func buildEnvoyAdminBind(alloc *structs.Allocation, serviceName, taskName string, taskEnv *taskenv.TaskEnv) string {
tg := alloc.Job.LookupTaskGroup(alloc.TaskGroup)
port := envoyBaseAdminPort
switch tg.Networks[0].Mode {
case "host":
interpolatedServices := taskenv.InterpolateServices(taskEnv, tg.Services)
for _, service := range interpolatedServices {
if service.Name == serviceName {
mapping := tg.Networks.Port(service.PortLabel)
port = mapping.Value
break
}
}
default:
for idx, task := range tg.Tasks {
if task.Name == taskName {
port += idx
break
}
}
}
return fmt.Sprintf("localhost:%d", port)
}
func (h *envoyBootstrapHook) writeConfig(filename, config string) error {
if err := ioutil.WriteFile(filename, []byte(config), 0440); err != nil {
_ = os.Remove(filename)
return err
}
return nil
}
func (h *envoyBootstrapHook) execute(cmd *exec.Cmd) (string, error) {
var (
stdout bytes.Buffer
stderr bytes.Buffer
)
cmd.Stdout = &stdout
cmd.Stderr = &stderr
if err := cmd.Run(); err != nil {
_, recoverable := err.(*exec.ExitError)
// ExitErrors are recoverable since they indicate the
// command was runnable but exited with a unsuccessful
// error code.
return stderr.String(), structs.NewRecoverableError(err, recoverable)
}
return stdout.String(), nil
}
// grpcAddress determines the Consul gRPC endpoint address to use.
//
// In host networking this will default to 127.0.0.1:8502.
// In bridge/cni networking this will default to unix://<socket>.
// In either case, CONSUL_GRPC_ADDR will override the default.
func (h *envoyBootstrapHook) grpcAddress(env map[string]string) string {
if address := env[grpcConsulVariable]; address != "" {
return address
}
tg := h.alloc.Job.LookupTaskGroup(h.alloc.TaskGroup)
switch tg.Networks[0].Mode {
case "host":
return grpcDefaultAddress
default:
return "unix://" + allocdir.AllocGRPCSocket
}
}
func (h *envoyBootstrapHook) proxyServiceID(group string, service *structs.Service) string {
return agentconsul.MakeAllocServiceID(h.alloc.ID, "group-"+group, service)
}
func (h *envoyBootstrapHook) newEnvoyBootstrapArgs(
group string, service *structs.Service,
grpcAddr, envoyAdminBind, siToken, filepath string,
) envoyBootstrapArgs {
var (
sidecarForID string // sidecar only
gateway string // gateway only
proxyID string // gateway only
namespace string
)
namespace = h.getConsulNamespace()
switch {
case service.Connect.HasSidecar():
sidecarForID = h.proxyServiceID(group, service)
case service.Connect.IsIngress():
proxyID = h.proxyServiceID(group, service)
gateway = "ingress"
case service.Connect.IsTerminating():
proxyID = h.proxyServiceID(group, service)
gateway = "terminating"
}
h.logger.Debug("bootstrapping envoy",
"sidecar_for", service.Name, "bootstrap_file", filepath,
"sidecar_for_id", sidecarForID, "grpc_addr", grpcAddr,
"admin_bind", envoyAdminBind, "gateway", gateway,
"proxy_id", proxyID, "namespace", namespace,
)
return envoyBootstrapArgs{
consulConfig: h.consulConfig,
sidecarFor: sidecarForID,
grpcAddr: grpcAddr,
envoyAdminBind: envoyAdminBind,
siToken: siToken,
gateway: gateway,
proxyID: proxyID,
namespace: namespace,
}
}
// envoyBootstrapArgs is used to accumulate CLI arguments that will be passed
// along to the exec invocation of consul which will then generate the bootstrap
// configuration file for envoy.
type envoyBootstrapArgs struct {
consulConfig consulTransportConfig
sidecarFor string // sidecars only
grpcAddr string
envoyAdminBind string
siToken string
gateway string // gateways only
proxyID string // gateways only
namespace string
}
// args returns the CLI arguments consul needs in the correct order, with the
// -token argument present or not present depending on whether it is set.
func (e envoyBootstrapArgs) args() []string {
arguments := []string{
"connect",
"envoy",
"-grpc-addr", e.grpcAddr,
"-http-addr", e.consulConfig.HTTPAddr,
"-admin-bind", e.envoyAdminBind,
"-bootstrap",
}
if v := e.sidecarFor; v != "" {
arguments = append(arguments, "-sidecar-for", v)
}
if v := e.gateway; v != "" {
arguments = append(arguments, "-gateway", v)
}
if v := e.proxyID; v != "" {
arguments = append(arguments, "-proxy-id", v)
}
if v := e.siToken; v != "" {
arguments = append(arguments, "-token", v)
}
if v := e.consulConfig.CAFile; v != "" {
arguments = append(arguments, "-ca-file", v)
}
if v := e.consulConfig.CertFile; v != "" {
arguments = append(arguments, "-client-cert", v)
}
if v := e.consulConfig.KeyFile; v != "" {
arguments = append(arguments, "-client-key", v)
}
if v := e.namespace; v != "" {
arguments = append(arguments, "-namespace", v)
}
return arguments
}
// env creates the context of environment variables to be used when exec-ing
// the consul command for generating the envoy bootstrap config. It is expected
// the value of os.Environ() is passed in to be appended to. Because these are
// appended at the end of what will be passed into Cmd.Env, they will override
// any pre-existing values (i.e. what the Nomad agent was launched with).
// https://golang.org/pkg/os/exec/#Cmd
func (e envoyBootstrapArgs) env(env []string) []string {
if v := e.consulConfig.Auth; v != "" {
env = append(env, fmt.Sprintf("%s=%s", "CONSUL_HTTP_AUTH", v))
}
if v := e.consulConfig.SSL; v != "" {
env = append(env, fmt.Sprintf("%s=%s", "CONSUL_HTTP_SSL", v))
}
if v := e.consulConfig.VerifySSL; v != "" {
env = append(env, fmt.Sprintf("%s=%s", "CONSUL_HTTP_SSL_VERIFY", v))
}
if v := e.namespace; v != "" {
env = append(env, fmt.Sprintf("%s=%s", "CONSUL_NAMESPACE", v))
}
return env
}
// maybeLoadSIToken reads the SI token saved to disk in the secrets directory
// by the service identities prestart hook. This envoy bootstrap hook blocks
// until the sids hook completes, so if the SI token is required to exist (i.e.
// Consul ACLs are enabled), it will be in place by the time we try to read it.
func (h *envoyBootstrapHook) maybeLoadSIToken(task, dir string) (string, error) {
tokenPath := filepath.Join(dir, sidsTokenFile)
token, err := ioutil.ReadFile(tokenPath)
if err != nil {
if !os.IsNotExist(err) {
h.logger.Error("failed to load SI token", "task", task, "error", err)
return "", errors.Wrapf(err, "failed to load SI token for %s", task)
}
h.logger.Trace("no SI token to load", "task", task)
return "", nil // token file does not exist
}
h.logger.Trace("recovered pre-existing SI token", "task", task)
return string(token), nil
}