opentofu/internal/command/show.go
Martin Atkins 89b05050ec core: Functional-style API for terraform.Context
Previously terraform.Context was built in an unfortunate way where all of
the data was provided up front in terraform.NewContext and then mutated
directly by subsequent operations. That made the data flow hard to follow,
commonly leading to bugs, and also meant that we were forced to take
various actions too early in terraform.NewContext, rather than waiting
until a more appropriate time during an operation.

This (enormous) commit changes terraform.Context so that its fields are
broadly just unchanging data about the execution context (current
workspace name, available plugins, etc) whereas the main data Terraform
works with arrives via individual method arguments and is returned in
return values.

Specifically, this means that terraform.Context no longer "has-a" config,
state, and "planned changes", instead holding on to those only temporarily
during an operation. The caller is responsible for propagating the outcome
of one step into the next step so that the data flow between operations is
actually visible.

However, since that's a change to the main entry points in the "terraform"
package, this commit also touches every file in the codebase which
interacted with those APIs. Most of the noise here is in updating tests
to take the same actions using the new API style, but this also affects
the main-code callers in the backends and in the command package.

My goal here was to refactor without changing observable behavior, but in
practice there are a couple externally-visible behavior variations here
that seemed okay in service of the broader goal:
 - The "terraform graph" command is no longer hooked directly into the
   core graph builders, because that's no longer part of the public API.
   However, I did include a couple new Context functions whose contract
   is to produce a UI-oriented graph, and _for now_ those continue to
   return the physical graph we use for those operations. There's no
   exported API for generating the "validate" and "eval" graphs, because
   neither is particularly interesting in its own right, and so
   "terraform graph" no longer supports those graph types.
 - terraform.NewContext no longer has the responsibility for collecting
   all of the provider schemas up front. Instead, we wait until we need
   them. However, that means that some of our error messages now have a
   slightly different shape due to unwinding through a differently-shaped
   call stack. As of this commit we also end up reloading the schemas
   multiple times in some cases, which is functionally acceptable but
   likely represents a performance regression. I intend to rework this to
   use caching, but I'm saving that for a later commit because this one is
   big enough already.

The proximal reason for this change is to resolve the chicken/egg problem
whereby there was previously no single point where we could apply "moved"
statements to the previous run state before creating a plan. With this
change in place, we can now do that as part of Context.Plan, prior to
forking the input state into the three separate state artifacts we use
during planning.

However, this is at least the third project in a row where the previous
API design led to piling more functionality into terraform.NewContext and
then working around the incorrect order of operations that produces, so
I intend that by paying the cost/risk of this large diff now we can in
turn reduce the cost/risk of future projects that relate to our main
workflow actions.
2021-08-30 13:59:14 -07:00

266 lines
7.0 KiB
Go

package command
import (
"fmt"
"os"
"strings"
"github.com/hashicorp/terraform/internal/backend"
"github.com/hashicorp/terraform/internal/command/arguments"
"github.com/hashicorp/terraform/internal/command/format"
"github.com/hashicorp/terraform/internal/command/jsonplan"
"github.com/hashicorp/terraform/internal/command/jsonstate"
"github.com/hashicorp/terraform/internal/command/views"
"github.com/hashicorp/terraform/internal/plans"
"github.com/hashicorp/terraform/internal/plans/planfile"
"github.com/hashicorp/terraform/internal/states/statefile"
"github.com/hashicorp/terraform/internal/states/statemgr"
"github.com/hashicorp/terraform/internal/tfdiags"
)
// ShowCommand is a Command implementation that reads and outputs the
// contents of a Terraform plan or state file.
type ShowCommand struct {
Meta
}
func (c *ShowCommand) Run(args []string) int {
args = c.Meta.process(args)
cmdFlags := c.Meta.defaultFlagSet("show")
var jsonOutput bool
cmdFlags.BoolVar(&jsonOutput, "json", false, "produce JSON output")
cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
if err := cmdFlags.Parse(args); err != nil {
c.Ui.Error(fmt.Sprintf("Error parsing command-line flags: %s\n", err.Error()))
return 1
}
args = cmdFlags.Args()
if len(args) > 2 {
c.Ui.Error(
"The show command expects at most two arguments.\n The path to a " +
"Terraform state or plan file, and optionally -json for json output.\n")
cmdFlags.Usage()
return 1
}
// Check for user-supplied plugin path
var err error
if c.pluginPath, err = c.loadPluginPath(); err != nil {
c.Ui.Error(fmt.Sprintf("Error loading plugin path: %s", err))
return 1
}
var diags tfdiags.Diagnostics
// Load the backend
b, backendDiags := c.Backend(nil)
diags = diags.Append(backendDiags)
if backendDiags.HasErrors() {
c.showDiagnostics(diags)
return 1
}
// We require a local backend
local, ok := b.(backend.Local)
if !ok {
c.showDiagnostics(diags) // in case of any warnings in here
c.Ui.Error(ErrUnsupportedLocalOp)
return 1
}
// This is a read-only command
c.ignoreRemoteBackendVersionConflict(b)
// the show command expects the config dir to always be the cwd
cwd, err := os.Getwd()
if err != nil {
c.Ui.Error(fmt.Sprintf("Error getting cwd: %s", err))
return 1
}
// Determine if a planfile was passed to the command
var planFile *planfile.Reader
if len(args) > 0 {
// We will handle error checking later on - this is just required to
// load the local context if the given path is successfully read as
// a planfile.
planFile, _ = c.PlanFile(args[0])
}
// Build the operation
opReq := c.Operation(b)
opReq.ConfigDir = cwd
opReq.PlanFile = planFile
opReq.ConfigLoader, err = c.initConfigLoader()
opReq.AllowUnsetVariables = true
if err != nil {
diags = diags.Append(err)
c.showDiagnostics(diags)
return 1
}
// Get the context
lr, _, ctxDiags := local.LocalRun(opReq)
diags = diags.Append(ctxDiags)
if ctxDiags.HasErrors() {
c.showDiagnostics(diags)
return 1
}
// Get the schemas from the context
schemas, moreDiags := lr.Core.Schemas(lr.Config, lr.InputState)
diags = diags.Append(moreDiags)
if moreDiags.HasErrors() {
c.showDiagnostics(diags)
return 1
}
var planErr, stateErr error
var plan *plans.Plan
var stateFile *statefile.File
// if a path was provided, try to read it as a path to a planfile
// if that fails, try to read the cli argument as a path to a statefile
if len(args) > 0 {
path := args[0]
plan, stateFile, planErr = getPlanFromPath(path)
if planErr != nil {
stateFile, stateErr = getStateFromPath(path)
if stateErr != nil {
c.Ui.Error(fmt.Sprintf(
"Terraform couldn't read the given file as a state or plan file.\n"+
"The errors while attempting to read the file as each format are\n"+
"shown below.\n\n"+
"State read error: %s\n\nPlan read error: %s",
stateErr,
planErr))
return 1
}
}
} else {
env, err := c.Workspace()
if err != nil {
c.Ui.Error(fmt.Sprintf("Error selecting workspace: %s", err))
return 1
}
stateFile, stateErr = getStateFromEnv(b, env)
if stateErr != nil {
c.Ui.Error(stateErr.Error())
return 1
}
}
if plan != nil {
if jsonOutput {
config := lr.Config
jsonPlan, err := jsonplan.Marshal(config, plan, stateFile, schemas)
if err != nil {
c.Ui.Error(fmt.Sprintf("Failed to marshal plan to json: %s", err))
return 1
}
c.Ui.Output(string(jsonPlan))
return 0
}
view := views.NewShow(arguments.ViewHuman, c.View)
view.Plan(plan, schemas)
return 0
}
if jsonOutput {
// At this point, it is possible that there is neither state nor a plan.
// That's ok, we'll just return an empty object.
jsonState, err := jsonstate.Marshal(stateFile, schemas)
if err != nil {
c.Ui.Error(fmt.Sprintf("Failed to marshal state to json: %s", err))
return 1
}
c.Ui.Output(string(jsonState))
} else {
if stateFile == nil {
c.Ui.Output("No state.")
return 0
}
c.Ui.Output(format.State(&format.StateOpts{
State: stateFile.State,
Color: c.Colorize(),
Schemas: schemas,
}))
}
return 0
}
func (c *ShowCommand) Help() string {
helpText := `
Usage: terraform [global options] show [options] [path]
Reads and outputs a Terraform state or plan file in a human-readable
form. If no path is specified, the current state will be shown.
Options:
-no-color If specified, output won't contain any color.
-json If specified, output the Terraform plan or state in
a machine-readable form.
`
return strings.TrimSpace(helpText)
}
func (c *ShowCommand) Synopsis() string {
return "Show the current state or a saved plan"
}
// getPlanFromPath returns a plan and statefile if the user-supplied path points
// to a planfile. If both plan and error are nil, the path is likely a
// directory. An error could suggest that the given path points to a statefile.
func getPlanFromPath(path string) (*plans.Plan, *statefile.File, error) {
pr, err := planfile.Open(path)
if err != nil {
return nil, nil, err
}
plan, err := pr.ReadPlan()
if err != nil {
return nil, nil, err
}
stateFile, err := pr.ReadStateFile()
return plan, stateFile, err
}
// getStateFromPath returns a statefile if the user-supplied path points to a statefile.
func getStateFromPath(path string) (*statefile.File, error) {
f, err := os.Open(path)
if err != nil {
return nil, fmt.Errorf("Error loading statefile: %s", err)
}
defer f.Close()
var stateFile *statefile.File
stateFile, err = statefile.Read(f)
if err != nil {
return nil, fmt.Errorf("Error reading %s as a statefile: %s", path, err)
}
return stateFile, nil
}
// getStateFromEnv returns the State for the current workspace, if available.
func getStateFromEnv(b backend.Backend, env string) (*statefile.File, error) {
// Get the state
stateStore, err := b.StateMgr(env)
if err != nil {
return nil, fmt.Errorf("Failed to load state manager: %s", err)
}
if err := stateStore.RefreshState(); err != nil {
return nil, fmt.Errorf("Failed to load state: %s", err)
}
sf := statemgr.Export(stateStore)
return sf, nil
}