// prepareContainerAccessEnvironment retrieves the environment, host machine, and access
// for working with containers.
func (p *ProvisionerAPI) prepareContainerAccessEnvironment() (environs.NetworkingEnviron, *state.Machine, common.AuthFunc, error) {
	cfg, err := p.st.EnvironConfig()
	if err != nil {
		return nil, nil, nil, errors.Annotate(err, "failed to get environment config")
	}
	environ, err := environs.New(cfg)
	if err != nil {
		return nil, nil, nil, errors.Annotate(err, "failed to construct an environment from config")
	}
	netEnviron, supported := environs.SupportsNetworking(environ)
	if !supported {
		// " not supported" will be appended to the message below.
		return nil, nil, nil, errors.NotSupportedf("environment %q networking", cfg.Name())
	}

	canAccess, err := p.getAuthFunc()
	if err != nil {
		return nil, nil, nil, errors.Annotate(err, "cannot authenticate request")
	}
	hostAuthTag := p.authorizer.GetAuthTag()
	if hostAuthTag == nil {
		return nil, nil, nil, errors.Errorf("authenticated entity tag is nil")
	}
	hostTag, err := names.ParseMachineTag(hostAuthTag.String())
	if err != nil {
		return nil, nil, nil, errors.Trace(err)
	}
	host, err := p.getMachine(canAccess, hostTag)
	if err != nil {
		return nil, nil, nil, errors.Trace(err)
	}
	return netEnviron, host, canAccess, nil
}

func (s *suite) bootstrapTestEnviron(c *gc.C) environs.NetworkingEnviron {
	env, err := bootstrap.Prepare(
		envtesting.BootstrapContext(c),
		s.ControllerStore,
		bootstrap.PrepareParams{
			ControllerConfig: testing.FakeControllerConfig(),
			ModelConfig:      s.TestConfig,
			ControllerName:   s.TestConfig["name"].(string),
			Cloud:            dummy.SampleCloudSpec(),
			AdminSecret:      AdminSecret,
		},
	)
	c.Assert(err, gc.IsNil, gc.Commentf("preparing environ %#v", s.TestConfig))
	c.Assert(env, gc.NotNil)
	netenv, supported := environs.SupportsNetworking(env)
	c.Assert(supported, jc.IsTrue)

	err = bootstrap.Bootstrap(envtesting.BootstrapContext(c), netenv, bootstrap.BootstrapParams{
		ControllerConfig: testing.FakeControllerConfig(),
		CloudName:        "dummy",
		Cloud: cloud.Cloud{
			Type:      "dummy",
			AuthTypes: []cloud.AuthType{cloud.EmptyAuthType},
		},
		AdminSecret:  AdminSecret,
		CAPrivateKey: testing.CAKey,
	})
	c.Assert(err, jc.ErrorIsNil)
	return netenv
}

func (*environSuite) TestSupportsNetworking(c *gc.C) {
	testConfig := minimalConfig(c)
	environ, err := local.Provider.Open(testConfig)
	c.Assert(err, jc.ErrorIsNil)
	_, ok := environs.SupportsNetworking(environ)
	c.Assert(ok, jc.IsFalse)
}

// ContainerManagerConfig returns information from the environment config that is
// needed for configuring the container manager.
func (p *ProvisionerAPI) ContainerManagerConfig(args params.ContainerManagerConfigParams) (params.ContainerManagerConfig, error) {
	var result params.ContainerManagerConfig
	config, err := p.st.EnvironConfig()
	if err != nil {
		return result, err
	}
	cfg := make(map[string]string)
	cfg[container.ConfigName] = container.DefaultNamespace

	switch args.Type {
	case instance.LXC:
		if useLxcClone, ok := config.LXCUseClone(); ok {
			cfg["use-clone"] = fmt.Sprint(useLxcClone)
		}
		if useLxcCloneAufs, ok := config.LXCUseCloneAUFS(); ok {
			cfg["use-aufs"] = fmt.Sprint(useLxcCloneAufs)
		}
		if lxcDefaultMTU, ok := config.LXCDefaultMTU(); ok {
			logger.Debugf("using default MTU %v for all LXC containers NICs", lxcDefaultMTU)
			cfg[container.ConfigLXCDefaultMTU] = fmt.Sprintf("%d", lxcDefaultMTU)
		}
	}

	if !environs.AddressAllocationEnabled() {
		// No need to even try checking the environ for support.
		logger.Debugf("address allocation feature flag not enabled")
		result.ManagerConfig = cfg
		return result, nil
	}

	// Create an environment to verify networking support.
	env, err := environs.New(config)
	if err != nil {
		return result, err
	}
	if netEnv, ok := environs.SupportsNetworking(env); ok {
		// Passing network.AnySubnet below should be interpreted by
		// the provider as "does ANY subnet support this".
		supported, err := netEnv.SupportsAddressAllocation(network.AnySubnet)
		if err == nil && supported {
			cfg[container.ConfigIPForwarding] = "true"
		} else if err != nil {
			// We log the error, but it's safe to ignore as it's not
			// critical.
			logger.Debugf("address allocation not supported (%v)", err)
		}
		// AWS requires NAT in place in order for hosted containers to
		// reach outside.
		if config.Type() == provider.EC2 {
			cfg[container.ConfigEnableNAT] = "true"
		}
	}

	result.ManagerConfig = cfg
	return result, nil
}

// NewWorker returns a machine undertaker worker that will watch for
// machines that need to be removed and remove them, cleaning up any
// necessary provider-level resources first.
func NewWorker(api Facade, env environs.Environ) (worker.Worker, error) {
	envNetworking, _ := environs.SupportsNetworking(env)
	w, err := watcher.NewNotifyWorker(watcher.NotifyConfig{
		Handler: &Undertaker{API: api, Releaser: envNetworking},
	})
	if err != nil {
		return nil, errors.Trace(err)
	}
	return w, nil
}

// networkingEnviron returns a environs.NetworkingEnviron instance from the
// current model config, if supported. If the model does not support
// environs.Networking, an error satisfying errors.IsNotSupported() will be
// returned.
func networkingEnviron(getter environs.EnvironConfigGetter) (environs.NetworkingEnviron, error) {
	env, err := environs.GetEnviron(getter, environs.New)
	if err != nil {
		return nil, errors.Annotate(err, "opening environment")
	}
	if netEnv, ok := environs.SupportsNetworking(env); ok {
		return netEnv, nil
	}
	return nil, errors.NotSupportedf("model networking features") // " not supported"
}

// NewWorker returns a worker that keeps track of
// IP address lifecycles, releaseing and removing Dead addresses.
func NewWorker(st stateAddresser) (worker.Worker, error) {
	config, err := st.EnvironConfig()
	if err != nil {
		return nil, errors.Trace(err)
	}
	environ, err := environs.New(config)
	if err != nil {
		return nil, errors.Trace(err)
	}
	// If netEnviron is nil the worker will start but won't do anything as
	// no IP addresses will be created or destroyed.
	netEnviron, _ := environs.SupportsNetworking(environ)
	a := newWorkerWithReleaser(st, netEnviron)
	return a, nil
}

// networkingEnviron returns a environs.NetworkingEnviron instance from the
// current model config, if supported. If the model does not support
// environs.Networking, an error satisfying errors.IsNotSupported() will be
// returned.
func networkingEnviron(api NetworkBacking) (environs.NetworkingEnviron, error) {
	envConfig, err := api.ModelConfig()
	if err != nil {
		return nil, errors.Annotate(err, "getting model config")
	}

	env, err := environs.New(envConfig)
	if err != nil {
		return nil, errors.Annotate(err, "opening model")
	}
	if netEnv, ok := environs.SupportsNetworking(env); ok {
		return netEnv, nil
	}
	return nil, errors.NotSupportedf("model networking features") // " not supported"
}

// networkingEnviron returns a environs.NetworkingEnviron instance
// from the current environment config, if supported. If the
// environment does not support environs.Networking, an error
// satisfying errors.IsNotSupported() will be returned.
func (api *subnetsAPI) networkingEnviron() (environs.NetworkingEnviron, error) {
	envConfig, err := api.backing.EnvironConfig()
	if err != nil {
		return nil, errors.Annotate(err, "getting environment config")
	}

	env, err := environs.New(envConfig)
	if err != nil {
		return nil, errors.Annotate(err, "opening environment")
	}
	if netEnv, ok := environs.SupportsNetworking(env); ok {
		return netEnv, nil
	}
	return nil, errors.NotSupportedf("environment networking features") // " not supported"
}

func (p *ProvisionerAPI) maybeGetNetworkingEnviron() (environs.NetworkingEnviron, error) {
	cfg, err := p.st.ModelConfig()
	if err != nil {
		return nil, errors.Annotate(err, "failed to get model config")
	}
	environ, err := environs.New(cfg)
	if err != nil {
		return nil, errors.Annotate(err, "failed to construct a model from config")
	}
	netEnviron, supported := environs.SupportsNetworking(environ)
	if !supported {
		// " not supported" will be appended to the message below.
		return nil, errors.NotSupportedf("model %q networking", cfg.Name())
	}
	return netEnviron, nil
}

func (s *suite) bootstrapTestEnviron(c *gc.C, preferIPv6 bool) environs.NetworkingEnviron {
	s.TestConfig["prefer-ipv6"] = preferIPv6
	cfg, err := config.New(config.NoDefaults, s.TestConfig)
	c.Assert(err, jc.ErrorIsNil)
	env, err := environs.Prepare(cfg, envtesting.BootstrapContext(c), s.ConfigStore)
	c.Assert(err, gc.IsNil, gc.Commentf("preparing environ %#v", s.TestConfig))
	c.Assert(env, gc.NotNil)
	netenv, supported := environs.SupportsNetworking(env)
	c.Assert(supported, jc.IsTrue)

	err = bootstrap.EnsureNotBootstrapped(netenv)
	c.Assert(err, jc.ErrorIsNil)
	err = bootstrap.Bootstrap(envtesting.BootstrapContext(c), netenv, bootstrap.BootstrapParams{})
	c.Assert(err, jc.ErrorIsNil)
	return netenv
}

// supportsSpaces checks if the environment implements NetworkingEnviron
// and also if it supports spaces.
func (api *spacesAPI) supportsSpaces() error {
	config, err := api.backing.EnvironConfig()
	if err != nil {
		return errors.Annotate(err, "getting environment config")
	}
	env, err := environs.New(config)
	if err != nil {
		return errors.Annotate(err, "validating environment config")
	}
	netEnv, ok := environs.SupportsNetworking(env)
	if !ok {
		return errors.NotSupportedf("networking")
	}
	ok, err = netEnv.SupportsSpaces()
	if err != nil {
		logger.Warningf("environment does not support spaces: %v", err)
	}
	return err
}

// getNetworkingEnviron checks if the environment implements NetworkingEnviron
// and also if it supports IP address allocation.
func (api *AddresserAPI) getNetworkingEnviron() (environs.NetworkingEnviron, bool, error) {
	config, err := api.st.EnvironConfig()
	if err != nil {
		return nil, false, errors.Annotate(err, "getting environment config")
	}
	env, err := environs.New(config)
	if err != nil {
		return nil, false, errors.Annotate(err, "validating environment config")
	}
	netEnv, ok := environs.SupportsNetworking(env)
	if !ok {
		return nil, false, nil
	}
	ok, err = netEnv.SupportsAddressAllocation(network.AnySubnet)
	if err != nil && !errors.IsNotSupported(err) {
		return nil, false, errors.Annotate(err, "checking allocation support")
	}
	return netEnv, ok, nil
}

// NetworkingEnvironFromModelConfig constructs and returns
// environs.NetworkingEnviron using the given configGetter. Returns an error
// satisfying errors.IsNotSupported() if the model config does not support
// networking features.
func NetworkingEnvironFromModelConfig(configGetter ModelConfigGetter) (environs.NetworkingEnviron, error) {
	modelConfig, err := configGetter.ModelConfig()
	if err != nil {
		return nil, errors.Annotate(err, "failed to get model config")
	}
	if modelConfig.Type() == "dummy" {
		return nil, errors.NotSupportedf("dummy provider network config")
	}
	model, err := environs.New(modelConfig)
	if err != nil {
		return nil, errors.Annotate(err, "failed to construct a model from config")
	}
	netEnviron, supported := environs.SupportsNetworking(model)
	if !supported {
		// " not supported" will be appended to the message below.
		return nil, errors.NotSupportedf("model %q networking", modelConfig.Name())
	}
	return netEnviron, nil
}

func (s *suite) bootstrapTestEnviron(c *gc.C, preferIPv6 bool) environs.NetworkingEnviron {
	s.TestConfig["prefer-ipv6"] = preferIPv6
	env, err := environs.Prepare(
		envtesting.BootstrapContext(c),
		s.ControllerStore,
		environs.PrepareParams{
			BaseConfig:     s.TestConfig,
			ControllerName: s.TestConfig["name"].(string),
			CloudName:      "dummy",
		},
	)
	c.Assert(err, gc.IsNil, gc.Commentf("preparing environ %#v", s.TestConfig))
	c.Assert(env, gc.NotNil)
	netenv, supported := environs.SupportsNetworking(env)
	c.Assert(supported, jc.IsTrue)

	err = bootstrap.Bootstrap(envtesting.BootstrapContext(c), netenv, bootstrap.BootstrapParams{})
	c.Assert(err, jc.ErrorIsNil)
	return netenv
}

func (dw *discoverspacesWorker) loop() (err error) {
	ensureClosed := func() {
		select {
		case <-dw.discoveringSpaces:
			// Already closed.
			return
		default:
			close(dw.discoveringSpaces)
		}
	}
	defer ensureClosed()
	modelCfg, err := dw.api.ModelConfig()
	if err != nil {
		return err
	}
	model, err := environs.New(modelCfg)
	if err != nil {
		return err
	}
	networkingModel, ok := environs.SupportsNetworking(model)

	if ok {
		err = dw.handleSubnets(networkingModel)
		if err != nil {
			return errors.Trace(err)
		}
	}
	close(dw.discoveringSpaces)

	// TODO(mfoord): we'll have a watcher here checking if we need to
	// update the spaces/subnets definition.
	dying := dw.tomb.Dying()
	for {
		select {
		case <-dying:
			return nil
		}
	}
	return nil
}

// SupportsSpaces checks if the environment implements NetworkingEnviron
// and also if it supports spaces.
func SupportsSpaces(backing NetworkBacking) error {
	config, err := backing.ModelConfig()
	if err != nil {
		return errors.Annotate(err, "getting model config")
	}
	env, err := environs.New(config)
	if err != nil {
		return errors.Annotate(err, "validating model config")
	}
	netEnv, ok := environs.SupportsNetworking(env)
	if !ok {
		return errors.NotSupportedf("networking")
	}
	ok, err = netEnv.SupportsSpaces()
	if !ok {
		if err != nil && !errors.IsNotSupported(err) {
			logger.Warningf("checking model spaces support failed with: %v", err)
		}
		return errors.NotSupportedf("spaces")
	}
	return nil
}

// Bootstrap bootstraps the given environment. The supplied constraints are
// used to provision the instance, and are also set within the bootstrapped
// environment.
func Bootstrap(ctx environs.BootstrapContext, environ environs.Environ, args BootstrapParams) error {
	cfg := environ.Config()
	network.InitializeFromConfig(cfg)
	if secret := cfg.AdminSecret(); secret == "" {
		return errors.Errorf("environment configuration has no admin-secret")
	}
	if authKeys := ssh.SplitAuthorisedKeys(cfg.AuthorizedKeys()); len(authKeys) == 0 {
		// Apparently this can never happen, so it's not tested. But, one day,
		// Config will act differently (it's pretty crazy that, AFAICT, the
		// authorized-keys are optional config settings... but it's impossible
		// to actually *create* a config without them)... and when it does,
		// we'll be here to catch this problem early.
		return errors.Errorf("environment configuration has no authorized-keys")
	}
	if _, hasCACert := cfg.CACert(); !hasCACert {
		return errors.Errorf("environment configuration has no ca-cert")
	}
	if _, hasCAKey := cfg.CAPrivateKey(); !hasCAKey {
		return errors.Errorf("environment configuration has no ca-private-key")
	}

	// Set default tools metadata source, add image metadata source,
	// then verify constraints. Providers may rely on image metadata
	// for constraint validation.
	var imageMetadata []*imagemetadata.ImageMetadata
	if args.MetadataDir != "" {
		var err error
		imageMetadata, err = setPrivateMetadataSources(environ, args.MetadataDir)
		if err != nil {
			return err
		}
	}
	if err := validateConstraints(environ, args.Constraints); err != nil {
		return err
	}

	_, supportsNetworking := environs.SupportsNetworking(environ)

	ctx.Infof("Bootstrapping environment %q", cfg.Name())
	logger.Debugf("environment %q supports service/machine networks: %v", cfg.Name(), supportsNetworking)
	disableNetworkManagement, _ := cfg.DisableNetworkManagement()
	logger.Debugf("network management by juju enabled: %v", !disableNetworkManagement)
	availableTools, err := findAvailableTools(environ, args.AgentVersion, args.Constraints.Arch, args.UploadTools)
	if errors.IsNotFound(err) {
		return errors.New(noToolsMessage)
	} else if err != nil {
		return err
	}
	if lxcMTU, ok := cfg.LXCDefaultMTU(); ok {
		logger.Debugf("using MTU %v for all created LXC containers' network interfaces", lxcMTU)
	}

	// If we're uploading, we must override agent-version;
	// if we're not uploading, we want to ensure we have an
	// agent-version set anyway, to appease FinishInstanceConfig.
	// In the latter case, setBootstrapTools will later set
	// agent-version to the correct thing.
	agentVersion := version.Current
	if args.AgentVersion != nil {
		agentVersion = *args.AgentVersion
	}
	if cfg, err = cfg.Apply(map[string]interface{}{
		"agent-version": agentVersion.String(),
	}); err != nil {
		return err
	}
	if err = environ.SetConfig(cfg); err != nil {
		return err
	}

	ctx.Infof("Starting new instance for initial state server")
	arch, series, finalizer, err := environ.Bootstrap(ctx, environs.BootstrapParams{
		Constraints:    args.Constraints,
		Placement:      args.Placement,
		AvailableTools: availableTools,
	})
	if err != nil {
		return err
	}

	matchingTools, err := availableTools.Match(coretools.Filter{
		Arch:   arch,
		Series: series,
	})
	if err != nil {
		return err
	}
	selectedTools, err := setBootstrapTools(environ, matchingTools)
	if err != nil {
		return err
	}
	if selectedTools.URL == "" {
		if !args.UploadTools {
			logger.Warningf("no prepackaged tools available")
		}
		ctx.Infof("Building tools to upload (%s)", selectedTools.Version)
		builtTools, err := sync.BuildToolsTarball(&selectedTools.Version.Number, cfg.AgentStream())
//.........这里部分代码省略.........

func (t *localServerSuite) TestSupportsNetworking(c *gc.C) {
	env := t.Prepare(c)
	_, supported := environs.SupportsNetworking(env)
	c.Assert(supported, jc.IsTrue)
}

func (t *localServerSuite) prepareEnviron(c *gc.C) environs.NetworkingEnviron {
	env := t.Prepare(c)
	netenv, supported := environs.SupportsNetworking(env)
	c.Assert(supported, jc.IsTrue)
	return netenv
}