forked from hashicorp/terraform
/
plan.go
176 lines (152 loc) · 4.56 KB
/
plan.go
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package terraform
import (
"bytes"
"encoding/gob"
"errors"
"fmt"
"io"
"log"
"sync"
"github.com/hashicorp/terraform/config/module"
)
func init() {
gob.Register(make([]interface{}, 0))
gob.Register(make([]map[string]interface{}, 0))
gob.Register(make(map[string]interface{}))
gob.Register(make(map[string]string))
}
// Plan represents a single Terraform execution plan, which contains
// all the information necessary to make an infrastructure change.
//
// A plan has to contain basically the entire state of the world
// necessary to make a change: the state, diff, config, backend config, etc.
// This is so that it can run alone without any other data.
type Plan struct {
Diff *Diff
Module *module.Tree
State *State
Vars map[string]interface{}
Targets []string
// Backend is the backend that this plan should use and store data with.
Backend *BackendState
once sync.Once
}
// Context returns a Context with the data encapsulated in this plan.
//
// The following fields in opts are overridden by the plan: Config,
// Diff, Variables.
//
// If State is not provided, it is set from the plan. If it _is_ provided,
// it must be Equal to the state stored in plan, but may have a newer
// serial.
func (p *Plan) Context(opts *ContextOpts) (*Context, error) {
opts.Diff = p.Diff
opts.Module = p.Module
opts.Targets = p.Targets
// If we are given a state in "base" then we'll use it, and otherwise
// we'll fall back on the state stashed in the plan. We do this because
// sometimes the caller has already persisted the plan's state by the
// time we get here, and we don't want to regress to the plan-time state
// serial if so.
if opts.State == nil {
opts.State = p.State
} else if !opts.State.Equal(p.State) {
// Even if we're overriding the state, it should be logically equal
// to what's in plan. The only valid change to have made by the time
// we get here is to have incremented the serial.
//
// Due to the fact that serialization may change the representation of
// the state, there is little chance that these aren't actually equal.
// Log the error condition for reference, but continue with the state
// we have.
log.Println("[ERROR] plan state and ContextOpts state are not equal")
}
opts.Variables = make(map[string]interface{})
for k, v := range p.Vars {
opts.Variables[k] = v
}
return NewContext(opts)
}
func (p *Plan) String() string {
buf := new(bytes.Buffer)
buf.WriteString("DIFF:\n\n")
buf.WriteString(p.Diff.String())
buf.WriteString("\n\nSTATE:\n\n")
buf.WriteString(p.State.String())
return buf.String()
}
func (p *Plan) init() {
p.once.Do(func() {
if p.Diff == nil {
p.Diff = new(Diff)
p.Diff.init()
}
if p.State == nil {
p.State = new(State)
p.State.init()
}
if p.Vars == nil {
p.Vars = make(map[string]interface{})
}
})
}
// The format byte is prefixed into the plan file format so that we have
// the ability in the future to change the file format if we want for any
// reason.
const planFormatMagic = "tfplan"
const planFormatVersion byte = 1
// ReadPlan reads a plan structure out of a reader in the format that
// was written by WritePlan.
func ReadPlan(src io.Reader) (*Plan, error) {
var result *Plan
var err error
n := 0
// Verify the magic bytes
magic := make([]byte, len(planFormatMagic))
for n < len(magic) {
n, err = src.Read(magic[n:])
if err != nil {
return nil, fmt.Errorf("error while reading magic bytes: %s", err)
}
}
if string(magic) != planFormatMagic {
return nil, fmt.Errorf("not a valid plan file")
}
// Verify the version is something we can read
var formatByte [1]byte
n, err = src.Read(formatByte[:])
if err != nil {
return nil, err
}
if n != len(formatByte) {
return nil, errors.New("failed to read plan version byte")
}
if formatByte[0] != planFormatVersion {
return nil, fmt.Errorf("unknown plan file version: %d", formatByte[0])
}
dec := gob.NewDecoder(src)
if err := dec.Decode(&result); err != nil {
return nil, err
}
return result, nil
}
// WritePlan writes a plan somewhere in a binary format.
func WritePlan(d *Plan, dst io.Writer) error {
// Write the magic bytes so we can determine the file format later
n, err := dst.Write([]byte(planFormatMagic))
if err != nil {
return err
}
if n != len(planFormatMagic) {
return errors.New("failed to write plan format magic bytes")
}
// Write a version byte so we can iterate on version at some point
n, err = dst.Write([]byte{planFormatVersion})
if err != nil {
return err
}
if n != 1 {
return errors.New("failed to write plan version byte")
}
return gob.NewEncoder(dst).Encode(d)
}