github.com/axw/juju@v0.0.0-20161005053422-4bd6544d08d4/upgrades/environconfig.go (about)

     1  // Copyright 2015 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package upgrades
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  
     9  	"github.com/juju/juju/environs"
    10  	"github.com/juju/juju/environs/config"
    11  	"github.com/juju/juju/state"
    12  )
    13  
    14  // environConfigUpdater is an interface used atomically write environment
    15  // config changes to the global state.
    16  type environConfigUpdater interface {
    17  	// UpdateModelConfig atomically updates and removes environment
    18  	// config attributes to the global state.
    19  	UpdateModelConfig(map[string]interface{}, []string, state.ValidateConfigFunc) error
    20  }
    21  
    22  // environConfigReader is an interface used to read the current environment
    23  // config from global state.
    24  type environConfigReader interface {
    25  	// ModelConfig reads the current environment config from global
    26  	// state.
    27  	ModelConfig() (*config.Config, error)
    28  }
    29  
    30  func upgradeModelConfig(
    31  	reader environConfigReader,
    32  	updater environConfigUpdater,
    33  	registry environs.ProviderRegistry,
    34  ) error {
    35  	cfg, err := reader.ModelConfig()
    36  	if err != nil {
    37  		return errors.Annotate(err, "reading model config")
    38  	}
    39  	provider, err := registry.Provider(cfg.Type())
    40  	if err != nil {
    41  		return errors.Annotate(err, "getting provider")
    42  	}
    43  
    44  	upgrader, ok := provider.(environs.ModelConfigUpgrader)
    45  	if !ok {
    46  		logger.Debugf("provider %q has no upgrades", cfg.Type())
    47  		return nil
    48  	}
    49  	newCfg, err := upgrader.UpgradeConfig(cfg)
    50  	if err != nil {
    51  		return errors.Annotate(err, "upgrading config")
    52  	}
    53  
    54  	newAttrs := newCfg.AllAttrs()
    55  	var removedAttrs []string
    56  	for key := range cfg.AllAttrs() {
    57  		if _, ok := newAttrs[key]; !ok {
    58  			removedAttrs = append(removedAttrs, key)
    59  		}
    60  	}
    61  	if err := updater.UpdateModelConfig(newAttrs, removedAttrs, nil); err != nil {
    62  		return errors.Annotate(err, "updating config in state")
    63  	}
    64  	return nil
    65  }