// getJoinedRelations finds out what relations the unit is *really* part of,
// working around the fact that pre-1.19 (1.18.1?) unit agents don't write a
// state dir for a relation until a remote unit joins.
func (u *Uniter) getJoinedRelations() (map[int]*uniter.Relation, error) {
	var joinedRelationTags []string
	for {
		var err error
		joinedRelationTags, err = u.unit.JoinedRelations()
		if err == nil {
			break
		}
		if params.IsCodeNotImplemented(err) {
			logger.Infof("waiting for state server to be upgraded")
			select {
			case <-u.tomb.Dying():
				return nil, tomb.ErrDying
			case <-time.After(15 * time.Second):
				continue
			}
		}
		return nil, err
	}
	joinedRelations := make(map[int]*uniter.Relation)
	for _, tag := range joinedRelationTags {
		relation, err := u.st.Relation(tag)
		if err != nil {
			return nil, err
		}
		joinedRelations[relation.Id()] = relation
	}
	return joinedRelations, nil
}

func (c *DestroyEnvironmentCommand) Run(ctx *cmd.Context) (result error) {
	store, err := configstore.Default()
	if err != nil {
		return fmt.Errorf("cannot open environment info storage: %v", err)
	}
	environ, err := environs.NewFromName(c.envName, store)
	if err != nil {
		if environs.IsEmptyConfig(err) {
			// Delete the .jenv file and call it done.
			ctx.Infof("removing empty environment file")
			return environs.DestroyInfo(c.envName, store)
		}
		return err
	}
	if !c.assumeYes {
		fmt.Fprintf(ctx.Stdout, destroyEnvMsg, environ.Name(), environ.Config().Type())

		scanner := bufio.NewScanner(ctx.Stdin)
		scanner.Scan()
		err := scanner.Err()
		if err != nil && err != io.EOF {
			return fmt.Errorf("Environment destruction aborted: %s", err)
		}
		answer := strings.ToLower(scanner.Text())
		if answer != "y" && answer != "yes" {
			return errors.New("environment destruction aborted")
		}
	}
	// If --force is supplied, then don't attempt to use the API.
	// This is necessary to destroy broken environments, where the
	// API server is inaccessible or faulty.
	if !c.force {
		defer func() {
			if result == nil {
				return
			}
			logger.Errorf(`failed to destroy environment %q
        
If the environment is unusable, then you may run

    juju destroy-environment --force

to forcefully destroy the environment. Upon doing so, review
your environment provider console for any resources that need
to be cleaned up.

`, c.envName)
		}()
		apiclient, err := juju.NewAPIClientFromName(c.envName)
		if err != nil {
			return fmt.Errorf("cannot connect to API: %v", err)
		}
		defer apiclient.Close()
		err = apiclient.DestroyEnvironment()
		if err != nil && !params.IsCodeNotImplemented(err) {
			return fmt.Errorf("destroying environment: %v", err)
		}
	}
	return environs.Destroy(environ, store)
}

// Environment returns the environment entity.
func (st *State) Environment() (*Environment, error) {
	var result params.EnvironmentResult
	err := st.call("CurrentEnvironment", nil, &result)
	if params.IsCodeNotImplemented(err) {
		// Fall back to using the 1.16 API.
		return st.environment1dot16()
	}
	if err != nil {
		return nil, err
	}
	if err := result.Error; err != nil {
		return nil, err
	}
	return &Environment{
		name: result.Name,
		uuid: result.UUID,
	}, nil
}

// initVersions collects state relevant to an upgrade decision. The returned
// agent and client versions, and the list of currently available tools, will
// always be accurate; the chosen version, and the flag indicating development
// mode, may remain blank until uploadTools or validate is called.
func (c *UpgradeJujuCommand) initVersions(client *api.Client, cfg *config.Config) (*upgradeContext, error) {
	agent, ok := cfg.AgentVersion()
	if !ok {
		// Can't happen. In theory.
		return nil, fmt.Errorf("incomplete environment configuration")
	}
	if c.Version == agent {
		return nil, errUpToDate
	}
	clientVersion := version.Current.Number
	findResult, err := client.FindTools(clientVersion.Major, -1, "", "")
	var availableTools coretools.List
	if params.IsCodeNotImplemented(err) {
		availableTools, err = findTools1dot17(cfg)
	} else {
		availableTools = findResult.List
	}
	if err != nil {
		return nil, err
	}
	err = findResult.Error
	if findResult.Error != nil {
		if !params.IsCodeNotFound(err) {
			return nil, err
		}
		if !c.UploadTools {
			// No tools found and we shouldn't upload any, so if we are not asking for a
			// major upgrade, pretend there is no more recent version available.
			if c.Version == version.Zero && agent.Major == clientVersion.Major {
				return nil, errUpToDate
			}
			return nil, err
		}
	}
	return &upgradeContext{
		agent:     agent,
		client:    clientVersion,
		chosen:    c.Version,
		tools:     availableTools,
		apiClient: client,
		config:    cfg,
	}, nil
}

func (task *provisionerTask) startMachine(machine *apiprovisioner.Machine) error {
	provisioningInfo, err := task.provisioningInfo(machine)
	if err != nil {
		return err
	}
	possibleTools, err := task.possibleTools(provisioningInfo.Series, provisioningInfo.Constraints)
	if err != nil {
		return task.setErrorStatus("cannot find tools for machine %q: %v", machine, err)
	}
	inst, metadata, networkInfo, err := task.broker.StartInstance(environs.StartInstanceParams{
		Constraints:       provisioningInfo.Constraints,
		Tools:             possibleTools,
		MachineConfig:     provisioningInfo.MachineConfig,
		Placement:         provisioningInfo.Placement,
		DistributionGroup: machine.DistributionGroup,
	})
	if err != nil {
		// Set the state to error, so the machine will be skipped next
		// time until the error is resolved, but don't return an
		// error; just keep going with the other machines.
		return task.setErrorStatus("cannot start instance for machine %q: %v", machine, err)
	}
	nonce := provisioningInfo.MachineConfig.MachineNonce
	networks, ifaces := task.prepareNetworkAndInterfaces(networkInfo)

	err = machine.SetInstanceInfo(inst.Id(), nonce, metadata, networks, ifaces)
	if err != nil && params.IsCodeNotImplemented(err) {
		return fmt.Errorf("cannot provision instance %v for machine %q with networks: not implemented", inst.Id(), machine)
	} else if err == nil {
		logger.Infof("started machine %s as instance %s with hardware %q, networks %v, interfaces %v", machine, inst.Id(), metadata, networks, ifaces)
		return nil
	}
	// We need to stop the instance right away here, set error status and go on.
	task.setErrorStatus("cannot register instance for machine %v: %v", machine, err)
	if err := task.broker.StopInstances(inst.Id()); err != nil {
		// We cannot even stop the instance, log the error and quit.
		logger.Errorf("cannot stop instance %q for machine %v: %v", inst.Id(), machine, err)
		return err
	}
	return nil
}

func (task *provisionerTask) provisioningInfo(machine *apiprovisioner.Machine) (*provisioningInfo, error) {
	stateInfo, apiInfo, err := task.auth.SetupAuthentication(machine)
	if err != nil {
		logger.Errorf("failed to setup authentication: %v", err)
		return nil, err
	}
	// Generated a nonce for the new instance, with the format: "machine-#:UUID".
	// The first part is a badge, specifying the tag of the machine the provisioner
	// is running on, while the second part is a random UUID.
	uuid, err := utils.NewUUID()
	if err != nil {
		return nil, err
	}
	// ProvisioningInfo is new in 1.20; wait for the API server to be upgraded
	// so we don't spew errors on upgrade.
	var pInfo *params.ProvisioningInfo
	for {
		if pInfo, err = machine.ProvisioningInfo(); err == nil {
			break
		}
		if params.IsCodeNotImplemented(err) {
			logger.Infof("waiting for state server to be upgraded")
			select {
			case <-task.tomb.Dying():
				return nil, tomb.ErrDying
			case <-time.After(15 * time.Second):
				continue
			}
		}
		return nil, err
	}
	nonce := fmt.Sprintf("%s:%s", task.machineTag, uuid.String())
	machineConfig := environs.NewMachineConfig(machine.Id(), nonce, pInfo.Networks, stateInfo, apiInfo)
	return &provisioningInfo{
		Constraints:   pInfo.Constraints,
		Series:        pInfo.Series,
		Placement:     pInfo.Placement,
		MachineConfig: machineConfig,
	}, nil
}

// uploadTools compiles jujud from $GOPATH and uploads it into the supplied
// storage. If no version has been explicitly chosen, the version number
// reported by the built tools will be based on the client version number.
// In any case, the version number reported will have a build component higher
// than that of any otherwise-matching available envtools.
// uploadTools resets the chosen version and replaces the available tools
// with the ones just uploaded.
func (context *upgradeContext) uploadTools(series []string) (err error) {
	// TODO(fwereade): this is kinda crack: we should not assume that
	// version.Current matches whatever source happens to be built. The
	// ideal would be:
	//  1) compile jujud from $GOPATH into some build dir
	//  2) get actual version with `jujud version`
	//  3) check actual version for compatibility with CLI tools
	//  4) generate unique build version with reference to available tools
	//  5) force-version that unique version into the dir directly
	//  6) archive and upload the build dir
	// ...but there's no way we have time for that now. In the meantime,
	// considering the use cases, this should work well enough; but it
	// won't detect an incompatible major-version change, which is a shame.
	if context.chosen == version.Zero {
		context.chosen = context.client
	}
	context.chosen = uploadVersion(context.chosen, context.tools)

	builtTools, err := sync.BuildToolsTarball(&context.chosen)
	if err != nil {
		return err
	}
	defer os.RemoveAll(builtTools.Dir)

	var uploaded *coretools.Tools
	toolsPath := path.Join(builtTools.Dir, builtTools.StorageName)
	logger.Infof("uploading tools %v (%dkB) to Juju state server", builtTools.Version, (builtTools.Size+512)/1024)
	uploaded, err = context.apiClient.UploadTools(toolsPath, builtTools.Version, series...)
	if params.IsCodeNotImplemented(err) {
		uploaded, err = context.uploadTools1dot17(builtTools, series...)
	}
	if err != nil {
		return err
	}
	context.tools = coretools.List{uploaded}
	return nil
}

func containerManagerConfig(
	containerType instance.ContainerType,
	provisioner *apiprovisioner.State,
	agentConfig agent.Config,
) (container.ManagerConfig, error) {
	// Ask the provisioner for the container manager configuration.
	managerConfigResult, err := provisioner.ContainerManagerConfig(
		params.ContainerManagerConfigParams{Type: containerType},
	)
	if params.IsCodeNotImplemented(err) {
		// We currently don't support upgrading;
		// revert to the old configuration.
		managerConfigResult.ManagerConfig = container.ManagerConfig{container.ConfigName: "juju"}
	}
	if err != nil {
		return nil, err
	}
	// If a namespace is specified, that should instead be used as the config name.
	if namespace := agentConfig.Value(agent.Namespace); namespace != "" {
		managerConfigResult.ManagerConfig[container.ConfigName] = namespace
	}
	managerConfig := container.ManagerConfig(managerConfigResult.ManagerConfig)
	return managerConfig, nil
}

func (c *DeployCommand) Run(ctx *cmd.Context) error {
	client, err := juju.NewAPIClientFromName(c.EnvName)
	if err != nil {
		return err
	}
	defer client.Close()

	attrs, err := client.EnvironmentGet()
	if err != nil {
		return err
	}
	conf, err := config.New(config.NoDefaults, attrs)
	if err != nil {
		return err
	}

	curl, err := resolveCharmURL(c.CharmName, client, conf)
	if err != nil {
		return err
	}

	repo, err := charm.InferRepository(curl.Reference, ctx.AbsPath(c.RepoPath))
	if err != nil {
		return err
	}

	repo = config.SpecializeCharmRepo(repo, conf)

	curl, err = addCharmViaAPI(client, ctx, curl, repo)
	if err != nil {
		return err
	}

	if c.BumpRevision {
		ctx.Infof("--upgrade (or -u) is deprecated and ignored; charms are always deployed with a unique revision.")
	}

	requestedNetworks, err := networkNamesToTags(parseNetworks(c.Networks))
	if err != nil {
		return err
	}
	// We need to ensure network names are valid below, but we don't need them here.
	_, err = networkNamesToTags(c.Constraints.IncludeNetworks())
	if err != nil {
		return err
	}
	_, err = networkNamesToTags(c.Constraints.ExcludeNetworks())
	if err != nil {
		return err
	}
	haveNetworks := len(requestedNetworks) > 0 || c.Constraints.HaveNetworks()

	charmInfo, err := client.CharmInfo(curl.String())
	if err != nil {
		return err
	}

	numUnits := c.NumUnits
	if charmInfo.Meta.Subordinate {
		if !constraints.IsEmpty(&c.Constraints) {
			return errors.New("cannot use --constraints with subordinate service")
		}
		if numUnits == 1 && c.ToMachineSpec == "" {
			numUnits = 0
		} else {
			return errors.New("cannot use --num-units or --to with subordinate service")
		}
	}
	serviceName := c.ServiceName
	if serviceName == "" {
		serviceName = charmInfo.Meta.Name
	}

	var configYAML []byte
	if c.Config.Path != "" {
		configYAML, err = c.Config.Read(ctx)
		if err != nil {
			return err
		}
	}
	err = client.ServiceDeployWithNetworks(
		curl.String(),
		serviceName,
		numUnits,
		string(configYAML),
		c.Constraints,
		c.ToMachineSpec,
		requestedNetworks,
	)
	if params.IsCodeNotImplemented(err) {
		if haveNetworks {
			return errors.New("cannot use --networks/--constraints networks=...: not supported by the API server")
		}
		err = client.ServiceDeploy(
			curl.String(),
			serviceName,
			numUnits,
			string(configYAML),
			c.Constraints,
			c.ToMachineSpec)
//.........这里部分代码省略.........

func (c *AddMachineCommand) Run(ctx *cmd.Context) error {
	if c.Placement != nil && c.Placement.Scope == "ssh" {
		args := manual.ProvisionMachineArgs{
			Host:    c.Placement.Directive,
			EnvName: c.EnvName,
			Stdin:   ctx.Stdin,
			Stdout:  ctx.Stdout,
			Stderr:  ctx.Stderr,
		}
		_, err := manual.ProvisionMachine(args)
		return err
	}

	client, err := juju.NewAPIClientFromName(c.EnvName)
	if err != nil {
		return err
	}
	defer client.Close()

	if c.Placement != nil && c.Placement.Scope == instance.MachineScope {
		// It does not make sense to add-machine <id>.
		return fmt.Errorf("machine-id cannot be specified when adding machines")
	}

	machineParams := params.AddMachineParams{
		Placement:   c.Placement,
		Series:      c.Series,
		Constraints: c.Constraints,
		Jobs:        []params.MachineJob{params.JobHostUnits},
	}
	results, err := client.AddMachines([]params.AddMachineParams{machineParams})
	if params.IsCodeNotImplemented(err) {
		if c.Placement != nil {
			containerType, parseErr := instance.ParseContainerType(c.Placement.Scope)
			if parseErr != nil {
				// The user specified a non-container placement directive:
				// return original API not implemented error.
				return err
			}
			machineParams.ContainerType = containerType
			machineParams.ParentId = c.Placement.Directive
			machineParams.Placement = nil
		}
		logger.Infof(
			"AddMachinesWithPlacement not supported by the API server, " +
				"falling back to 1.18 compatibility mode",
		)
		results, err = client.AddMachines1dot18([]params.AddMachineParams{machineParams})
	}
	if err != nil {
		return err
	}

	// Currently, only one machine is added, but in future there may be several added in one call.
	machineInfo := results[0]
	if machineInfo.Error != nil {
		return machineInfo.Error
	}
	machineId := machineInfo.Machine

	if names.IsContainerMachine(machineId) {
		ctx.Infof("created container %v", machineId)
	} else {
		ctx.Infof("created machine %v", machineId)
	}
	return nil
}