// 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
}

// 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
	cfg := make(map[string]string)
	cfg[container.ConfigModelUUID] = p.st.ModelUUID()

	switch args.Type {
	case instance.LXD:
		// TODO(jam): DefaultMTU needs to be handled here
		// TODO(jam): Do we want to handle ImageStream here, or do we
		// hide it from them? (all cached images must come from the
		// same image stream?)
	}

	result.ManagerConfig = cfg
	return result, nil
}

// 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] = "juju"
	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)
		}
	}
	result.ManagerConfig = cfg
	return result, nil
}