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| 1 // Copyright 2012, 2013 Canonical Ltd. | |
| 2 // Licensed under the AGPLv3, see LICENCE file for details. | |
| 3 | |
| 4 package apiuniter | |
| 5 | |
| 6 import ( | |
| 7 "errors" | |
| 8 "fmt" | |
| 9 "os" | |
| 10 | |
| 11 "launchpad.net/juju-core/charm" | |
| 12 "launchpad.net/juju-core/utils" | |
| 13 uhook "launchpad.net/juju-core/worker/apiuniter/hook" | |
| 14 ) | |
| 15 | |
| 16 // Op enumerates the operations the uniter can perform. | |
| 17 type Op string | |
| 18 | |
| 19 const ( | |
| 20 // Install indicates that the uniter is installing the charm. | |
| 21 Install Op = "install" | |
| 22 | |
| 23 // RunHook indicates that the uniter is running a hook. | |
| 24 RunHook Op = "run-hook" | |
| 25 | |
| 26 // Upgrade indicates that the uniter is upgrading the charm. | |
| 27 Upgrade Op = "upgrade" | |
| 28 | |
| 29 // Continue indicates that the uniter should run ModeContinue | |
| 30 // to determine the next operation. | |
| 31 Continue Op = "continue" | |
| 32 ) | |
| 33 | |
| 34 // OpStep describes the recorded progression of an operation. | |
| 35 type OpStep string | |
| 36 | |
| 37 const ( | |
| 38 // Queued indicates that the uniter should undertake the operation | |
| 39 // as soon as possible. | |
| 40 Queued OpStep = "queued" | |
| 41 | |
| 42 // Pending indicates that the uniter has started, but not completed, | |
| 43 // the operation. | |
| 44 Pending OpStep = "pending" | |
| 45 | |
| 46 // Done indicates that the uniter has completed the operation, | |
| 47 // but may not yet have synchronized all necessary secondary state. | |
| 48 Done OpStep = "done" | |
| 49 ) | |
| 50 | |
| 51 // State defines the local persistent state of the uniter, excluding relation | |
| 52 // state. | |
| 53 type State struct { | |
| 54 // Started indicates whether the start hook has run. | |
| 55 Started bool | |
| 56 | |
| 57 // Op indicates the current operation. | |
| 58 Op Op | |
| 59 | |
| 60 // OpStep indicates the current operation's progression. | |
| 61 OpStep OpStep | |
| 62 | |
| 63 // Hook holds hook information relevant to the current operation. If Op | |
| 64 // is Continue, it holds the last hook that was executed; if Op is RunHo
ok, | |
| 65 // it holds the running hook; if Op is Upgrade, a non-nil hook indicates | |
| 66 // that the uniter should return to that hook's Pending state after the | |
| 67 // upgrade is complete (instead of running an upgrade-charm hook). | |
| 68 Hook *uhook.Info `yaml:"hook,omitempty"` | |
| 69 | |
| 70 // Charm describes the charm being deployed by an Install or Upgrade | |
| 71 // operation, and is otherwise blank. | |
| 72 CharmURL *charm.URL `yaml:"charm,omitempty"` | |
| 73 } | |
| 74 | |
| 75 // validate returns an error if the state violates expectations. | |
| 76 func (st State) validate() (err error) { | |
| 77 defer utils.ErrorContextf(&err, "invalid uniter state") | |
| 78 hasHook := st.Hook != nil | |
| 79 hasCharm := st.CharmURL != nil | |
| 80 switch st.Op { | |
| 81 case Install: | |
| 82 if hasHook { | |
| 83 return fmt.Errorf("unexpected hook info") | |
| 84 } | |
| 85 fallthrough | |
| 86 case Upgrade: | |
| 87 if !hasCharm { | |
| 88 return fmt.Errorf("missing charm URL") | |
| 89 } | |
| 90 case Continue, RunHook: | |
| 91 if !hasHook { | |
| 92 return fmt.Errorf("missing hook info") | |
| 93 } else if hasCharm { | |
| 94 return fmt.Errorf("unexpected charm URL") | |
| 95 } | |
| 96 default: | |
| 97 return fmt.Errorf("unknown operation %q", st.Op) | |
| 98 } | |
| 99 switch st.OpStep { | |
| 100 case Queued, Pending, Done: | |
| 101 default: | |
| 102 return fmt.Errorf("unknown operation step %q", st.OpStep) | |
| 103 } | |
| 104 if hasHook { | |
| 105 return st.Hook.Validate() | |
| 106 } | |
| 107 return nil | |
| 108 } | |
| 109 | |
| 110 // StateFile holds the disk state for a uniter. | |
| 111 type StateFile struct { | |
| 112 path string | |
| 113 } | |
| 114 | |
| 115 // NewStateFile returns a new StateFile using path. | |
| 116 func NewStateFile(path string) *StateFile { | |
| 117 return &StateFile{path} | |
| 118 } | |
| 119 | |
| 120 var ErrNoStateFile = errors.New("uniter state file does not exist") | |
| 121 | |
| 122 // Read reads a State from the file. If the file does not exist it returns | |
| 123 // ErrNoStateFile. | |
| 124 func (f *StateFile) Read() (*State, error) { | |
| 125 var st State | |
| 126 if err := utils.ReadYaml(f.path, &st); err != nil { | |
| 127 if os.IsNotExist(err) { | |
| 128 return nil, ErrNoStateFile | |
| 129 } | |
| 130 } | |
| 131 if err := st.validate(); err != nil { | |
| 132 return nil, fmt.Errorf("cannot read charm state at %q: %v", f.pa
th, err) | |
| 133 } | |
| 134 return &st, nil | |
| 135 } | |
| 136 | |
| 137 // Write stores the supplied state to the file. | |
| 138 func (f *StateFile) Write(started bool, op Op, step OpStep, hi *uhook.Info, url
*charm.URL) error { | |
| 139 st := &State{ | |
| 140 Started: started, | |
| 141 Op: op, | |
| 142 OpStep: step, | |
| 143 Hook: hi, | |
| 144 CharmURL: url, | |
| 145 } | |
| 146 if err := st.validate(); err != nil { | |
| 147 panic(err) | |
| 148 } | |
| 149 return utils.WriteYaml(f.path, st) | |
| 150 } | |
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