terraform/backend/local/backend_plan.go

package local

import (
	"context"
	"fmt"
	"log"
	"os"
	"strings"

	"github.com/hashicorp/errwrap"
	"github.com/hashicorp/terraform/backend"
	"github.com/hashicorp/terraform/command/format"
	"github.com/hashicorp/terraform/terraform"
)

func (b *Local) opPlan(
	ctx context.Context,
	op *backend.Operation,
	runningOp *backend.RunningOperation) {
	log.Printf("[INFO] backend/local: starting Plan operation")

	if b.CLI != nil && op.Plan != nil {
		b.CLI.Output(b.Colorize().Color(
			"[reset][bold][yellow]" +
				"The plan command received a saved plan file as input. This command\n" +
				"will output the saved plan. This will not modify the already-existing\n" +
				"plan. If you wish to generate a new plan, please pass in a configuration\n" +
				"directory as an argument.\n\n"))
	}

	// Setup our count hook that keeps track of resource changes
	countHook := new(CountHook)
	if b.ContextOpts == nil {
		b.ContextOpts = new(terraform.ContextOpts)
	}
	old := b.ContextOpts.Hooks
	defer func() { b.ContextOpts.Hooks = old }()
	b.ContextOpts.Hooks = append(b.ContextOpts.Hooks, countHook)

	// Get our context
	tfCtx, _, err := b.context(op)
	if err != nil {
		runningOp.Err = err
		return
	}

	// Setup the state
	runningOp.State = tfCtx.State()

	// If we're refreshing before plan, perform that
	if op.PlanRefresh {
		log.Printf("[INFO] backend/local: plan calling Refresh")

		b.CLI.Output(b.Colorize().Color(strings.TrimSpace(planRefreshing) + "\n"))
		_, err := tfCtx.Refresh()
		if err != nil {
			runningOp.Err = errwrap.Wrapf("Error refreshing state: {{err}}", err)
			return
		}
	}

	// Perform the plan
	log.Printf("[INFO] backend/local: plan calling Plan")
	plan, err := tfCtx.Plan()
	if err != nil {
		runningOp.Err = errwrap.Wrapf("Error running plan: {{err}}", err)
		return
	}

	// Record state
	runningOp.PlanEmpty = plan.Diff.Empty()

	// Save the plan to disk
	if path := op.PlanOutPath; path != "" {
		// Write the backend if we have one
		plan.Backend = op.PlanOutBackend

		log.Printf("[INFO] backend/local: writing plan output to: %s", path)
		f, err := os.Create(path)
		if err == nil {
			err = terraform.WritePlan(plan, f)
		}
		f.Close()
		if err != nil {
			runningOp.Err = fmt.Errorf("Error writing plan file: %s", err)
			return
		}
	}

	// Perform some output tasks if we have a CLI to output to.
	if b.CLI != nil {
		if plan.Diff.Empty() {
			b.CLI.Output(b.Colorize().Color(strings.TrimSpace(planNoChanges)))
			return
		}

		if path := op.PlanOutPath; path == "" {
			b.CLI.Output(strings.TrimSpace(planHeaderNoOutput) + "\n")
		} else {
			b.CLI.Output(fmt.Sprintf(
				strings.TrimSpace(planHeaderYesOutput)+"\n",
				path))
		}

		b.CLI.Output(format.Plan(&format.PlanOpts{
			Plan:        plan,
			Color:       b.Colorize(),
			ModuleDepth: -1,
		}))

		b.CLI.Output(b.Colorize().Color(fmt.Sprintf(
			"[reset][bold]Plan:[reset] "+
				"%d to add, %d to change, %d to destroy.",
			countHook.ToAdd+countHook.ToRemoveAndAdd,
			countHook.ToChange,
			countHook.ToRemove+countHook.ToRemoveAndAdd)))
	}
}

const planHeaderNoOutput = `
The Terraform execution plan has been generated and is shown below.
Resources are shown in alphabetical order for quick scanning. Green resources
will be created (or destroyed and then created if an existing resource
exists), yellow resources are being changed in-place, and red resources
will be destroyed. Cyan entries are data sources to be read.

Note: You didn't specify an "-out" parameter to save this plan, so when
"apply" is called, Terraform can't guarantee this is what will execute.
`

const planHeaderYesOutput = `
The Terraform execution plan has been generated and is shown below.
Resources are shown in alphabetical order for quick scanning. Green resources
will be created (or destroyed and then created if an existing resource
exists), yellow resources are being changed in-place, and red resources
will be destroyed. Cyan entries are data sources to be read.

Your plan was also saved to the path below. Call the "apply" subcommand
with this plan file and Terraform will exactly execute this execution
plan.

Path: %s
`

const planNoChanges = `
[reset][bold][green]No changes. Infrastructure is up-to-date.[reset][green]

This means that Terraform could not detect any differences between your
configuration and real physical resources that exist. As a result, Terraform
doesn't need to do anything.
`

const planRefreshing = `
[reset][bold]Refreshing Terraform state in-memory prior to plan...[reset]
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.
`