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  • Committer: Nicholas Skaggs
  • Date: 2016-10-27 20:23:11 UTC
  • Revision ID: nicholas.skaggs@canonical.com-20161027202311-sux4jk2o73p1d6rg
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src/github.com/juju/juju/worker/apicaller/manifold.go
 
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// Copyright 2015 Canonical Ltd.
 
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// Licensed under the AGPLv3, see LICENCE file for details.
 
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package apicaller
 
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import (
 
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        "github.com/juju/errors"
 
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        "github.com/juju/juju/agent"
 
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        "github.com/juju/juju/api"
 
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        "github.com/juju/juju/api/base"
 
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        "github.com/juju/juju/worker"
 
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        "github.com/juju/juju/worker/dependency"
 
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)
 
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// ManifoldConfig defines the names of the manifolds on which a Manifold will depend.
 
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type ManifoldConfig struct {
 
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        AgentName string
 
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}
 
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// Manifold returns a manifold whose worker wraps an API connection made on behalf of
 
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// the dependency identified by AgentName.
 
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func Manifold(config ManifoldConfig) dependency.Manifold {
 
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        return dependency.Manifold{
 
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                Inputs: []string{
 
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                        config.AgentName,
 
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                },
 
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                Output: outputFunc,
 
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                Start:  startFunc(config),
 
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        }
 
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}
 
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// startFunc returns a StartFunc that creates a worker based on the manifolds
 
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// named in the supplied config.
 
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func startFunc(config ManifoldConfig) dependency.StartFunc {
 
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        return func(getResource dependency.GetResourceFunc) (worker.Worker, error) {
 
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                // Get dependencies and open a connection.
 
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                var a agent.Agent
 
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                if err := getResource(config.AgentName, &a); err != nil {
 
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                        return nil, err
 
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                }
 
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                conn, err := openConnection(a)
 
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                if err != nil {
 
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                        return nil, errors.Annotate(err, "cannot open api")
 
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                }
 
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                // Add the environment uuid to agent config if not present.
 
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                currentConfig := a.CurrentConfig()
 
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                if currentConfig.Model().Id() == "" {
 
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                        err := a.ChangeConfig(func(setter agent.ConfigSetter) error {
 
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                                modelTag, err := conn.ModelTag()
 
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                                if err != nil {
 
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                                        return errors.Annotate(err, "no model uuid set on api")
 
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                                }
 
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                                return setter.Migrate(agent.MigrateParams{
 
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                                        Model: modelTag,
 
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                                })
 
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                        })
 
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                        if err != nil {
 
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                                logger.Warningf("unable to save model uuid: %v", err)
 
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                                // Not really fatal, just annoying.
 
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                        }
 
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                }
 
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                // Return the worker.
 
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                return newApiConnWorker(conn)
 
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        }
 
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}
 
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// outputFunc extracts an API connection from a *apiConnWorker.
 
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func outputFunc(in worker.Worker, out interface{}) error {
 
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        inWorker, _ := in.(*apiConnWorker)
 
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        if inWorker == nil {
 
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                return errors.Errorf("in should be a %T; got %T", inWorker, in)
 
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        }
 
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        switch outPointer := out.(type) {
 
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        case *base.APICaller:
 
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                *outPointer = inWorker.conn
 
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        case *api.Connection:
 
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                // Using api.Connection is strongly discouraged as consumers
 
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                // of this API connection should not be able to close it. This
 
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                // option is only available to support legacy upgrade steps.
 
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                *outPointer = inWorker.conn
 
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        default:
 
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                return errors.Errorf("out should be *base.APICaller or *api.Connection; got %T", out)
 
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        }
 
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        return nil
 
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}