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connect_native_hook.go
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connect_native_hook.go
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package taskrunner
import (
"context"
"fmt"
"io"
"os"
"path/filepath"
"github.com/hashicorp/go-hclog"
"github.com/hashicorp/nomad/client/allocdir"
ifs "github.com/hashicorp/nomad/client/allocrunner/interfaces"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/hashicorp/nomad/nomad/structs/config"
)
const (
connectNativeHookName = "connect_native"
)
type connectNativeHookConfig struct {
consulShareTLS bool
consul consulTransportConfig
alloc *structs.Allocation
logger hclog.Logger
}
func newConnectNativeHookConfig(alloc *structs.Allocation, consul *config.ConsulConfig, logger hclog.Logger) *connectNativeHookConfig {
return &connectNativeHookConfig{
alloc: alloc,
logger: logger,
consulShareTLS: consul.ShareSSL == nil || *consul.ShareSSL, // default enabled
consul: newConsulTransportConfig(consul),
}
}
// connectNativeHook manages additional automagic configuration for a connect
// native task.
//
// If nomad client is configured to talk to Consul using TLS (or other special
// auth), the native task will inherit that configuration EXCEPT for the consul
// token.
//
// If consul is configured with ACLs enabled, a Service Identity token will be
// generated on behalf of the native service and supplied to the task.
//
// If the alloc is configured with bridge networking enabled, the standard
// CONSUL_HTTP_ADDR environment variable is defaulted to the unix socket created
// for the alloc by the consul_grpc_sock_hook alloc runner hook.
type connectNativeHook struct {
// alloc is the allocation with the connect native task being run
alloc *structs.Allocation
// consulShareTLS is used to toggle whether the TLS configuration of the
// Nomad Client may be shared with Connect Native applications.
consulShareTLS bool
// consulConfig is used to enable the connect native enabled task to
// communicate with consul directly, as is necessary for the task to request
// its connect mTLS certificates.
consulConfig consulTransportConfig
// logger is used to log things
logger hclog.Logger
}
func newConnectNativeHook(c *connectNativeHookConfig) *connectNativeHook {
return &connectNativeHook{
alloc: c.alloc,
consulShareTLS: c.consulShareTLS,
consulConfig: c.consul,
logger: c.logger.Named(connectNativeHookName),
}
}
func (connectNativeHook) Name() string {
return connectNativeHookName
}
// merge b into a, overwriting on conflicts
func merge(a, b map[string]string) {
for k, v := range b {
a[k] = v
}
}
func (h *connectNativeHook) Prestart(
ctx context.Context,
request *ifs.TaskPrestartRequest,
response *ifs.TaskPrestartResponse) error {
if !request.Task.Kind.IsConnectNative() {
response.Done = true
return nil
}
environment := make(map[string]string)
if h.consulShareTLS {
// copy TLS certificates
if err := h.copyCertificates(h.consulConfig, request.TaskDir.SecretsDir); err != nil {
h.logger.Error("failed to copy Consul TLS certificates", "error", err)
return err
}
// set environment variables for communicating with Consul agent, but
// only if those environment variables are not already set
merge(environment, h.tlsEnv(request.TaskEnv.EnvMap))
}
if err := h.maybeSetSITokenEnv(request.TaskDir.SecretsDir, request.Task.Name, environment); err != nil {
h.logger.Error("failed to load Consul Service Identity Token", "error", err, "task", request.Task.Name)
return err
}
merge(environment, h.bridgeEnv(request.TaskEnv.EnvMap))
merge(environment, h.hostEnv(request.TaskEnv.EnvMap))
// tls/acl setup for native task done
response.Done = true
response.Env = environment
return nil
}
const (
secretCAFilename = "consul_ca_file.pem"
secretCertfileFilename = "consul_cert_file.pem"
secretKeyfileFilename = "consul_key_file.pem"
)
func (h *connectNativeHook) copyCertificates(consulConfig consulTransportConfig, dir string) error {
if err := h.copyCertificate(consulConfig.CAFile, dir, secretCAFilename); err != nil {
return err
}
if err := h.copyCertificate(consulConfig.CertFile, dir, secretCertfileFilename); err != nil {
return err
}
if err := h.copyCertificate(consulConfig.KeyFile, dir, secretKeyfileFilename); err != nil {
return err
}
return nil
}
func (connectNativeHook) copyCertificate(source, dir, name string) error {
if source == "" {
return nil
}
original, err := os.Open(source)
if err != nil {
return fmt.Errorf("failed to open consul TLS certificate: %w", err)
}
defer original.Close()
destination := filepath.Join(dir, name)
fd, err := os.Create(destination)
if err != nil {
return fmt.Errorf("failed to create secrets/%s: %w", name, err)
}
defer fd.Close()
if _, err := io.Copy(fd, original); err != nil {
return fmt.Errorf("failed to copy certificate secrets/%s: %w", name, err)
}
if err := fd.Sync(); err != nil {
return fmt.Errorf("failed to write secrets/%s: %w", name, err)
}
return nil
}
// tlsEnv creates a set of additional of environment variables to be used when launching
// the connect native task. This will enable the task to communicate with Consul
// if Consul has transport security turned on.
//
// We do NOT set CONSUL_HTTP_TOKEN from the nomad agent's consul config, as that
// is a separate security concern addressed by the service identity hook.
func (h *connectNativeHook) tlsEnv(env map[string]string) map[string]string {
m := make(map[string]string)
if _, exists := env["CONSUL_CACERT"]; !exists && h.consulConfig.CAFile != "" {
m["CONSUL_CACERT"] = filepath.Join("/secrets", secretCAFilename)
}
if _, exists := env["CONSUL_CLIENT_CERT"]; !exists && h.consulConfig.CertFile != "" {
m["CONSUL_CLIENT_CERT"] = filepath.Join("/secrets", secretCertfileFilename)
}
if _, exists := env["CONSUL_CLIENT_KEY"]; !exists && h.consulConfig.KeyFile != "" {
m["CONSUL_CLIENT_KEY"] = filepath.Join("/secrets", secretKeyfileFilename)
}
if _, exists := env["CONSUL_HTTP_SSL"]; !exists {
if v := h.consulConfig.SSL; v != "" {
m["CONSUL_HTTP_SSL"] = v
}
}
if _, exists := env["CONSUL_HTTP_SSL_VERIFY"]; !exists {
if v := h.consulConfig.VerifySSL; v != "" {
m["CONSUL_HTTP_SSL_VERIFY"] = v
}
}
return m
}
// bridgeEnv creates a set of additional environment variables to be used when launching
// the connect native task. This will enable the task to communicate with Consul
// if the task is running inside an alloc's network namespace (i.e. bridge mode).
//
// Sets CONSUL_HTTP_ADDR if not already set.
// Sets CONSUL_TLS_SERVER_NAME if not already set, and consul tls is enabled.
func (h *connectNativeHook) bridgeEnv(env map[string]string) map[string]string {
if h.alloc.AllocatedResources.Shared.Networks[0].Mode != "bridge" {
return nil
}
result := make(map[string]string)
if _, exists := env["CONSUL_HTTP_ADDR"]; !exists {
result["CONSUL_HTTP_ADDR"] = "unix:///" + allocdir.AllocHTTPSocket
}
if _, exists := env["CONSUL_TLS_SERVER_NAME"]; !exists {
if v := h.consulConfig.SSL; v != "" {
result["CONSUL_TLS_SERVER_NAME"] = "localhost"
}
}
return result
}
// hostEnv creates a set of additional environment variables to be used when launching
// the connect native task. This will enable the task to communicate with Consul
// if the task is running in host network mode.
//
// Sets CONSUL_HTTP_ADDR if not already set.
func (h *connectNativeHook) hostEnv(env map[string]string) map[string]string {
if h.alloc.AllocatedResources.Shared.Networks[0].Mode != "host" {
return nil
}
if _, exists := env["CONSUL_HTTP_ADDR"]; !exists {
return map[string]string{
"CONSUL_HTTP_ADDR": h.consulConfig.HTTPAddr,
}
}
return nil
}
// maybeSetSITokenEnv will set the CONSUL_HTTP_TOKEN environment variable in
// the given env map, if the token is found to exist in the task's secrets
// directory AND the CONSUL_HTTP_TOKEN environment variable is not already set.
//
// Following the pattern of the envoy_bootstrap_hook, the Consul Service Identity
// ACL Token is generated prior to this hook, if Consul ACLs are enabled. This is
// done in the sids_hook, which places the token at secrets/si_token in the task
// workspace. The content of that file is the SI token specific to this task
// instance.
func (h *connectNativeHook) maybeSetSITokenEnv(dir, task string, env map[string]string) error {
if _, exists := env["CONSUL_HTTP_TOKEN"]; exists {
// Consul token was already set - typically by using the Vault integration
// and a template block to set the environment. Ignore the SI token as
// the configured token takes precedence.
return nil
}
token, err := os.ReadFile(filepath.Join(dir, sidsTokenFile))
if err != nil {
if !os.IsNotExist(err) {
return fmt.Errorf("failed to load SI token for native task %s: %w", task, err)
}
h.logger.Trace("no SI token to load for native task", "task", task)
return nil // token file DNE; acls not enabled
}
h.logger.Trace("recovered pre-existing SI token for native task", "task", task)
env["CONSUL_HTTP_TOKEN"] = string(token)
return nil
}