github.com/mhilton/juju-juju@v0.0.0-20150901100907-a94dd2c73455/cmd/juju/environment/jenv.go

// Copyright 2015 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package environment

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/juju/cmd"
	"github.com/juju/errors"
	"github.com/juju/names"
	"gopkg.in/yaml.v1"

	"github.com/juju/juju/cmd/envcmd"
	"github.com/juju/juju/environs/configstore"
	"github.com/juju/juju/juju/osenv"
)

// JenvCommand imports the given Juju generated jenv file into the local
// JUJU_HOME environments directory.
type JenvCommand struct {
	cmd.CommandBase
	jenvFile cmd.FileVar
	envName  string
}

const jenvHelpDoc = `
Copy the provided Juju generated jenv file to the proper location inside your
local JUJU_HOME. Also switch to using the resulting environment as the default
one. This way it is possible to import and use jenv files generated by other
Juju commands such as "juju user add".

Example:

  juju environment jenv my-env.jenv (my-env.jenv is the path to the jenv file)
  juju environment jenv my-env.jenv ec2 (copy and rename the environment)
`

func (c *JenvCommand) Info() *cmd.Info {
	return &cmd.Info{
		Name:    "jenv",
		Args:    "<path/to/file.jenv> [<environment name>]",
		Purpose: "import previously generated Juju environment files",
		Doc:     strings.TrimSpace(jenvHelpDoc),
	}
}

func (c *JenvCommand) Init(args []string) error {
	if len(args) == 0 {
		return errors.New("no jenv file provided")
	}

	// Store the path to the jenv file.
	if err := c.jenvFile.Set(args[0]); err != nil {
		return errors.Annotate(err, "invalid jenv path")
	}
	args = args[1:]

	if len(args) > 0 {
		// Store and validate the provided environment name.
		c.envName, args = args[0], args[1:]
		if !names.IsValidUser(c.envName) {
			return errors.Errorf("invalid environment name %q", c.envName)
		}
	} else {
		// Retrieve the environment name from the jenv file name.
		base := filepath.Base(c.jenvFile.Path)
		c.envName = base[:len(base)-len(filepath.Ext(base))]
	}

	// No other arguments are expected.
	return cmd.CheckEmpty(args)
}

func (c *JenvCommand) Run(ctx *cmd.Context) error {
	// Read data from the provided jenv file.
	data, err := c.jenvFile.Read(ctx)
	if err != nil {
		if os.IsNotExist(errors.Cause(err)) {
			return errors.NotFoundf("jenv file %q", c.jenvFile.Path)
		}
		return errors.Annotatef(err, "cannot read the provided jenv file %q", c.jenvFile.Path)
	}

	// Open the config store.
	store, err := configstore.Default()
	if err != nil {
		return errors.Annotate(err, "cannot get config store")
	}

	// Create and update the new environment info object.
	info := store.CreateInfo(c.envName)
	if err := updateEnvironmentInfo(info, data); err != nil {
		return errors.Annotatef(err, "invalid jenv file %q", c.jenvFile.Path)
	}

	// Write the environment info to JUJU_HOME.
	if err := info.Write(); err != nil {
		if errors.Cause(err) == configstore.ErrEnvironInfoAlreadyExists {
			descriptiveErr := errors.Errorf("an environment named %q already exists: "+
				"you can provide a second parameter to rename the environment",
				c.envName)
			return errors.Wrap(err, descriptiveErr)
		}
		return errors.Annotate(err, "cannot write the jenv file")
	}

	// Switch to the new environment.
	oldEnvName, err := switchEnvironment(c.envName)
	if err != nil {
		return errors.Annotatef(err, "cannot switch to the new environment %q", c.envName)
	}
	if oldEnvName == "" {
		fmt.Fprintf(ctx.Stdout, "-> %s\n", c.envName)
	} else {
		fmt.Fprintf(ctx.Stdout, "%s -> %s\n", oldEnvName, c.envName)
	}
	return nil
}

// updateEnvironmentInfo updates the given environment info with the values
// stored in the provided YAML encoded data.
func updateEnvironmentInfo(info configstore.EnvironInfo, data []byte) error {
	var values configstore.EnvironInfoData
	if err := yaml.Unmarshal(data, &values); err != nil {
		return errors.Annotate(err, "cannot unmarshal jenv data")
	}

	// Ensure the required values are present.
	if missing := getMissingEnvironmentInfoFields(values); len(missing) != 0 {
		return errors.Errorf("missing required fields in jenv data: %s", strings.Join(missing, ", "))
	}

	// Update the environment info.
	info.SetAPICredentials(configstore.APICredentials{
		User:     values.User,
		Password: values.Password,
	})
	info.SetAPIEndpoint(configstore.APIEndpoint{
		Addresses:   values.StateServers,
		Hostnames:   values.ServerHostnames,
		CACert:      values.CACert,
		EnvironUUID: values.EnvironUUID,
	})
	info.SetBootstrapConfig(values.Config)
	return nil
}

// getMissingEnvironmentInfoFields returns a list of field names missing in the
// given environment info values. The only fields taken into consideration here
// are the ones explicitly set by the "juju user add" command.
func getMissingEnvironmentInfoFields(values configstore.EnvironInfoData) (missing []string) {
	if values.User == "" {
		missing = append(missing, "User")
	}
	if values.Password == "" {
		missing = append(missing, "Password")
	}
	if values.EnvironUUID == "" {
		missing = append(missing, "EnvironUUID")
	}
	if len(values.StateServers) == 0 {
		missing = append(missing, "StateServers")
	}
	if values.CACert == "" {
		missing = append(missing, "CACert")
	}
	return missing
}

// switchEnvironment changes the default environment to the given name and
// return, if set, the current default environment name.
func switchEnvironment(envName string) (string, error) {
	if defaultEnv := os.Getenv(osenv.JujuEnvEnvKey); defaultEnv != "" {
		return "", errors.Errorf("cannot switch when %s is overriding the environment (set to %q)", osenv.JujuEnvEnvKey, defaultEnv)
	}
	currentEnv, err := envcmd.GetDefaultEnvironment()
	if err != nil {
		return "", errors.Annotate(err, "cannot get the default environment")
	}
	if err := envcmd.WriteCurrentEnvironment(envName); err != nil {
		return "", errors.Trace(err)
	}
	return currentEnv, nil
}