backport of commit 8a88d3c7f9

command/output.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/convert"
 	ctyjson "github.com/zclconf/go-cty/cty/json"
 
 	"github.com/hashicorp/terraform/addrs"
@@ -17,14 +19,19 @@ import (
 // from a Terraform state and prints it.
 type OutputCommand struct {
 	Meta
+
+	// Unit tests may set rawPrint to capture the output from the -raw
+	// option, which would normally go to stdout directly.
+	rawPrint func(string)
 }
 
 func (c *OutputCommand) Run(args []string) int {
 	args = c.Meta.process(args)
 	var module, statePath string
-	var jsonOutput bool
+	var jsonOutput, rawOutput bool
 	cmdFlags := c.Meta.defaultFlagSet("output")
 	cmdFlags.BoolVar(&jsonOutput, "json", false, "json")
+	cmdFlags.BoolVar(&rawOutput, "raw", false, "raw")
 	cmdFlags.StringVar(&statePath, "state", "", "path")
 	cmdFlags.StringVar(&module, "module", "", "module")
 	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
@@ -42,6 +49,18 @@ func (c *OutputCommand) Run(args []string) int {
 		return 1
 	}
 
+	if jsonOutput && rawOutput {
+		c.Ui.Error("The -raw and -json options are mutually-exclusive.\n")
+		cmdFlags.Usage()
+		return 1
+	}
+
+	if rawOutput && len(args) == 0 {
+		c.Ui.Error("You must give the name of a single output value when using the -raw option.\n")
+		cmdFlags.Usage()
+		return 1
+	}
+
 	name := ""
 	if len(args) > 0 {
 		name = args[0]
@@ -187,14 +206,65 @@ func (c *OutputCommand) Run(args []string) int {
 	}
 	v := os.Value
 
-	if jsonOutput {
+	switch {
+	case jsonOutput:
 		jsonOutput, err := ctyjson.Marshal(v, v.Type())
 		if err != nil {
 			return 1
 		}
 
 		c.Ui.Output(string(jsonOutput))
-	} else {
+	case rawOutput:
+		strV, err := convert.Convert(v, cty.String)
+		if err != nil {
+			diags = diags.Append(tfdiags.Sourceless(
+				tfdiags.Error,
+				"Unsupported value for raw output",
+				fmt.Sprintf(
+					"The -raw option only supports strings, numbers, and boolean values, but output value %q is %s.\n\nUse the -json option for machine-readable representations of output values that have complex types.",
+					name, v.Type().FriendlyName(),
+				),
+			))
+			c.showDiagnostics(diags)
+			return 1
+		}
+		if strV.IsNull() {
+			diags = diags.Append(tfdiags.Sourceless(
+				tfdiags.Error,
+				"Unsupported value for raw output",
+				fmt.Sprintf(
+					"The value for output value %q is null, so -raw mode cannot print it.",
+					name,
+				),
+			))
+			c.showDiagnostics(diags)
+			return 1
+		}
+		if !strV.IsKnown() {
+			// Since we're working with values from the state it would be very
+			// odd to end up in here, but we'll handle it anyway to avoid a
+			// panic in case our rules somehow change in future.
+			diags = diags.Append(tfdiags.Sourceless(
+				tfdiags.Error,
+				"Unsupported value for raw output",
+				fmt.Sprintf(
+					"The value for output value %q won't be known until after a successful terraform apply, so -raw mode cannot print it.",
+					name,
+				),
+			))
+			c.showDiagnostics(diags)
+			return 1
+		}
+		// If we get out here then we should have a valid string to print.
+		// We're writing it directly to the output here so that a shell caller
+		// will get exactly the value and no extra whitespace.
+		str := strV.AsString()
+		if c.rawPrint != nil {
+			c.rawPrint(str)
+		} else {
+			fmt.Print(str)
+		}
+	default:
 		result := repl.FormatValue(v, 0)
 		c.Ui.Output(result)
 	}
@@ -219,8 +289,12 @@ Options:
   -no-color        If specified, output won't contain any color.
 
   -json            If specified, machine readable output will be
-                   printed in JSON format
+                   printed in JSON format.
 
+  -raw             For value types that can be automatically
+                   converted to a string, will print the raw
+                   string directly, rather than a human-oriented
+                   representation of the value.
 `
 	return strings.TrimSpace(helpText)
 }

command/output_test.go

@@ -130,6 +130,92 @@ func TestOutput_json(t *testing.T) {
 	}
 }
 
+func TestOutput_raw(t *testing.T) {
+	originalState := states.BuildState(func(s *states.SyncState) {
+		s.SetOutputValue(
+			addrs.OutputValue{Name: "str"}.Absolute(addrs.RootModuleInstance),
+			cty.StringVal("bar"),
+			false,
+		)
+		s.SetOutputValue(
+			addrs.OutputValue{Name: "multistr"}.Absolute(addrs.RootModuleInstance),
+			cty.StringVal("bar\nbaz"),
+			false,
+		)
+		s.SetOutputValue(
+			addrs.OutputValue{Name: "num"}.Absolute(addrs.RootModuleInstance),
+			cty.NumberIntVal(2),
+			false,
+		)
+		s.SetOutputValue(
+			addrs.OutputValue{Name: "bool"}.Absolute(addrs.RootModuleInstance),
+			cty.True,
+			false,
+		)
+		s.SetOutputValue(
+			addrs.OutputValue{Name: "obj"}.Absolute(addrs.RootModuleInstance),
+			cty.EmptyObjectVal,
+			false,
+		)
+		s.SetOutputValue(
+			addrs.OutputValue{Name: "null"}.Absolute(addrs.RootModuleInstance),
+			cty.NullVal(cty.String),
+			false,
+		)
+	})
+
+	statePath := testStateFile(t, originalState)
+
+	tests := map[string]struct {
+		WantOutput string
+		WantErr    bool
+	}{
+		"str":      {WantOutput: "bar"},
+		"multistr": {WantOutput: "bar\nbaz"},
+		"num":      {WantOutput: "2"},
+		"bool":     {WantOutput: "true"},
+		"obj":      {WantErr: true},
+		"null":     {WantErr: true},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			var printed string
+			ui := cli.NewMockUi()
+			c := &OutputCommand{
+				Meta: Meta{
+					testingOverrides: metaOverridesForProvider(testProvider()),
+					Ui:               ui,
+				},
+				rawPrint: func(s string) {
+					printed = s
+				},
+			}
+			args := []string{
+				"-state", statePath,
+				"-raw",
+				name,
+			}
+			code := c.Run(args)
+
+			if code != 0 {
+				if !test.WantErr {
+					t.Errorf("unexpected failure\n%s", ui.ErrorWriter.String())
+				}
+				return
+			}
+
+			if test.WantErr {
+				t.Fatalf("succeeded, but want error")
+			}
+
+			if got, want := printed, test.WantOutput; got != want {
+				t.Errorf("wrong result\ngot:  %q\nwant: %q", got, want)
+			}
+		})
+	}
+}
+
 func TestOutput_emptyOutputs(t *testing.T) {
 	originalState := states.NewState()
 	statePath := testStateFile(t, originalState)

website/docs/commands/output.html.markdown

@@ -24,6 +24,11 @@ The command-line flags are all optional. The list of available flags are:
 * `-json` - If specified, the outputs are formatted as a JSON object, with
     a key per output. If `NAME` is specified, only the output specified will be
     returned. This can be piped into tools such as `jq` for further processing.
+* `-raw` - If specified, Terraform will convert the specified output value to a
+    string and print that string directly to the output, without any special
+    formatting. This can be convenient when working with shell scripts, but
+    it only supports string, number, and boolean values. Use `-json` instead
+    for processing complex data types.
 * `-no-color` - If specified, output won't contain any color.
 * `-state=path` - Path to the state file. Defaults to "terraform.tfstate".
     Ignored when [remote state](/docs/state/remote.html) is used.
@@ -87,21 +92,31 @@ instance_ips = [
 ## Use in automation
 
 The `terraform output` command by default displays in a human-readable format,
-which can change over time to improve clarity. For use in automation, use
-`-json` to output the stable JSON format. You can parse the output using a JSON
-command-line parser such as [jq](https://stedolan.github.io/jq/).
+which can change over time to improve clarity.
 
-For string outputs, you can remove quotes using `jq -r`:
+For scripting and automation, use `-json` to produce the stable JSON format.
+You can parse the output using a JSON command-line parser such as
+[jq](https://stedolan.github.io/jq/):
 
 ```shellsession
-$ terraform output -json lb_address | jq -r .
-my-app-alb-1657023003.us-east-1.elb.amazonaws.com
+$ terraform output -json instance_ips | jq -r '.[0]'
+54.43.114.12
 ```
 
-To query for a particular value in a list, use `jq` with an index filter. For
-example, to query for the first instance's IP address:
+For the common case of directly using a string value in a shell script, you
+can use `-raw` instead, which will print the string directly with no extra
+escaping or whitespace.
 
 ```shellsession
-$ terraform output -json instance_ips | jq '.[0]'
-"54.43.114.12"
+$ terraform output -raw lb_address
+my-app-alb-1657023003.us-east-1.elb.amazonaws.com
 ```
+
+The `-raw` option works only with values that Terraform can automatically
+convert to strings. Use `-json` instead, possibly combined with `jq`, to
+work with complex-typed values such as objects.
+
+Terraform strings are sequences of Unicode characters rather than raw bytes,
+so the `-raw` output will be UTF-8 encoded when it contains non-ASCII
+characters. If you need a different character encoding, use a separate command
+such as `iconv` to transcode Terraform's raw output.