github.com/turtlemonvh/terraform@v0.6.9-0.20151204001754-8e40b6b855e8/terraform/plan.go (about)

     1  package terraform
     2  
     3  import (
     4  	"bytes"
     5  	"encoding/gob"
     6  	"errors"
     7  	"fmt"
     8  	"io"
     9  	"sync"
    10  
    11  	"github.com/hashicorp/terraform/config/module"
    12  )
    13  
    14  func init() {
    15  	gob.Register(make([]interface{}, 0))
    16  	gob.Register(make([]map[string]interface{}, 0))
    17  	gob.Register(make(map[string]interface{}))
    18  	gob.Register(make(map[string]string))
    19  }
    20  
    21  // Plan represents a single Terraform execution plan, which contains
    22  // all the information necessary to make an infrastructure change.
    23  type Plan struct {
    24  	Diff   *Diff
    25  	Module *module.Tree
    26  	State  *State
    27  	Vars   map[string]string
    28  
    29  	once sync.Once
    30  }
    31  
    32  // Context returns a Context with the data encapsulated in this plan.
    33  //
    34  // The following fields in opts are overridden by the plan: Config,
    35  // Diff, State, Variables.
    36  func (p *Plan) Context(opts *ContextOpts) *Context {
    37  	opts.Diff = p.Diff
    38  	opts.Module = p.Module
    39  	opts.State = p.State
    40  	opts.Variables = p.Vars
    41  	return NewContext(opts)
    42  }
    43  
    44  func (p *Plan) String() string {
    45  	buf := new(bytes.Buffer)
    46  	buf.WriteString("DIFF:\n\n")
    47  	buf.WriteString(p.Diff.String())
    48  	buf.WriteString("\n\nSTATE:\n\n")
    49  	buf.WriteString(p.State.String())
    50  	return buf.String()
    51  }
    52  
    53  func (p *Plan) init() {
    54  	p.once.Do(func() {
    55  		if p.Diff == nil {
    56  			p.Diff = new(Diff)
    57  			p.Diff.init()
    58  		}
    59  
    60  		if p.State == nil {
    61  			p.State = new(State)
    62  			p.State.init()
    63  		}
    64  
    65  		if p.Vars == nil {
    66  			p.Vars = make(map[string]string)
    67  		}
    68  	})
    69  }
    70  
    71  // The format byte is prefixed into the plan file format so that we have
    72  // the ability in the future to change the file format if we want for any
    73  // reason.
    74  const planFormatMagic = "tfplan"
    75  const planFormatVersion byte = 1
    76  
    77  // ReadPlan reads a plan structure out of a reader in the format that
    78  // was written by WritePlan.
    79  func ReadPlan(src io.Reader) (*Plan, error) {
    80  	var result *Plan
    81  	var err error
    82  	n := 0
    83  
    84  	// Verify the magic bytes
    85  	magic := make([]byte, len(planFormatMagic))
    86  	for n < len(magic) {
    87  		n, err = src.Read(magic[n:])
    88  		if err != nil {
    89  			return nil, fmt.Errorf("error while reading magic bytes: %s", err)
    90  		}
    91  	}
    92  	if string(magic) != planFormatMagic {
    93  		return nil, fmt.Errorf("not a valid plan file")
    94  	}
    95  
    96  	// Verify the version is something we can read
    97  	var formatByte [1]byte
    98  	n, err = src.Read(formatByte[:])
    99  	if err != nil {
   100  		return nil, err
   101  	}
   102  	if n != len(formatByte) {
   103  		return nil, errors.New("failed to read plan version byte")
   104  	}
   105  
   106  	if formatByte[0] != planFormatVersion {
   107  		return nil, fmt.Errorf("unknown plan file version: %d", formatByte[0])
   108  	}
   109  
   110  	dec := gob.NewDecoder(src)
   111  	if err := dec.Decode(&result); err != nil {
   112  		return nil, err
   113  	}
   114  
   115  	return result, nil
   116  }
   117  
   118  // WritePlan writes a plan somewhere in a binary format.
   119  func WritePlan(d *Plan, dst io.Writer) error {
   120  	// Write the magic bytes so we can determine the file format later
   121  	n, err := dst.Write([]byte(planFormatMagic))
   122  	if err != nil {
   123  		return err
   124  	}
   125  	if n != len(planFormatMagic) {
   126  		return errors.New("failed to write plan format magic bytes")
   127  	}
   128  
   129  	// Write a version byte so we can iterate on version at some point
   130  	n, err = dst.Write([]byte{planFormatVersion})
   131  	if err != nil {
   132  		return err
   133  	}
   134  	if n != 1 {
   135  		return errors.New("failed to write plan version byte")
   136  	}
   137  
   138  	return gob.NewEncoder(dst).Encode(d)
   139  }