Added fmt action

DOCS.md

@@ -182,11 +182,25 @@ pipeline:
 +     - destroy
 ```
 
+Formatting the Terraform configuration files can be done by specifying the `fmt` action. Use `fmt_options` parameter to handle formatting options.
+
+```yaml
+pipeline:
+  fmt:
+    image: jmccann/drone-terraform:5
++   actions:
++     - fmt
++   fmt_options:
++     write: false
++     diff: true
++     check: true
+```
+
 # Parameter Reference
 
 actions
 : List of terraform actions to perform with the plugin.  List includes:
-`validate`, `plan`, `apply`, `plan-destroy`, `destroy`.
+`fmt`, `validate`, `plan`, `apply`, `plan-destroy`, `destroy`.
 
 init_options
 : contains the configuration for the Terraform backend.
@@ -202,6 +216,21 @@ init_options.lock
 init_options.lock-timeout
 : Duration to wait for a state lock. Default `0s`.
 
+fmt_options
+: contains the configuration for the fmt action.
+
+fmt_options.list
+: List files whose formatting differs (disabled if using STDIN). Default `true`.
+
+fmt_options.write
+: Write result to source file instead of STDOUT (disabled if using STDIN or -check). Default `true`.
+
+fmt_options.diff
+: Display diffs of formatting changes. Default `false`.
+
+fmt_options.check
+: Check if the input is formatted. Exit status will be 0 if all input is properly formatted and non-zero otherwise. Default `false`.
+
 vars
 : a map of variables to pass to the Terraform `plan` and `apply` commands.
 Each value is passed as a `-var <key>=<value>` option.

main.go

@@ -43,6 +43,11 @@ func main() {
 			Usage:  "options for the init command. See https://www.terraform.io/docs/commands/init.html",
 			EnvVar: "PLUGIN_INIT_OPTIONS",
 		},
+		cli.StringFlag{
+			Name:   "fmt_options",
+			Usage:  "options for the fmt command. See https://www.terraform.io/docs/commands/fmt.html",
+			EnvVar: "PLUGIN_FMT_OPTIONS",
+		},
 		cli.IntFlag{
 			Name:   "parallelism",
 			Usage:  "The number of concurrent operations as Terraform walks its graph",
@@ -134,6 +139,8 @@ func run(c *cli.Context) error {
 
 	initOptions := InitOptions{}
 	json.Unmarshal([]byte(c.String("init_options")), &initOptions)
+	fmtOptions := FmtOptions{}
+	json.Unmarshal([]byte(c.String("fmt_options")), &fmtOptions)
 
 	plugin := Plugin{
 		Config: Config{
@@ -141,6 +148,7 @@ func run(c *cli.Context) error {
 			Vars:        vars,
 			Secrets:     secrets,
 			InitOptions: initOptions,
+			FmtOptions:  fmtOptions,
 			Cacert:      c.String("ca_cert"),
 			Sensitive:   c.Bool("sensitive"),
 			RoleARN:     c.String("role_arn_to_assume"),

plugin.go

@@ -25,6 +25,7 @@ type (
 		Vars        map[string]string
 		Secrets     map[string]string
 		InitOptions InitOptions
+		FmtOptions  FmtOptions
 		Cacert      string
 		Sensitive   bool
 		RoleARN     string
@@ -48,6 +49,14 @@ type (
 		LockTimeout   string   `json:"lock-timeout"`
 	}
 
+	// FmtOptions fmt options for the Terraform's fmt command
+	FmtOptions struct {
+		List  *bool `json:"list"`
+		Write *bool `json:"write"`
+		Diff  *bool `json:"diff"`
+		Check *bool `json:"check"`
+	}
+
 	// Plugin represents the plugin instance to be executed
 	Plugin struct {
 		Config    Config
@@ -94,6 +103,8 @@ func (p Plugin) Exec() error {
 	// Add commands listed from Actions
 	for _, action := range p.Config.Actions {
 		switch action {
+		case "fmt":
+			commands = append(commands, tfFmt(p.Config))
 		case "validate":
 			commands = append(commands, tfValidate(p.Config))
 		case "plan":
@@ -105,7 +116,7 @@ func (p Plugin) Exec() error {
 		case "destroy":
 			commands = append(commands, tfDestroy(p.Config))
 		default:
-			return fmt.Errorf("valid actions are: validate, plan, apply, plan-destroy, destroy.  You provided %s", action)
+			return fmt.Errorf("valid actions are: fmt, validate, plan, apply, plan-destroy, destroy.  You provided %s", action)
 		}
 	}
 
@@ -321,6 +332,28 @@ func tfValidate(config Config) *exec.Cmd {
 	)
 }
 
+func tfFmt(config Config) *exec.Cmd {
+	args := []string{
+		"fmt",
+	}
+	if config.FmtOptions.List != nil {
+		args = append(args, fmt.Sprintf("-list=%t", *config.FmtOptions.List))
+	}
+	if config.FmtOptions.Write != nil {
+		args = append(args, fmt.Sprintf("-write=%t", *config.FmtOptions.Write))
+	}
+	if config.FmtOptions.Diff != nil {
+		args = append(args, fmt.Sprintf("-diff=%t", *config.FmtOptions.Diff))
+	}
+	if config.FmtOptions.Check != nil {
+		args = append(args, fmt.Sprintf("-check=%t", *config.FmtOptions.Check))
+	}
+	return exec.Command(
+		"terraform",
+		args...,
+	)
+}
+
 func vars(vs map[string]string) []string {
 	var args []string
 	for k, v := range vs {

plugin_test.go

@@ -148,4 +148,60 @@ func TestPlugin(t *testing.T) {
 			}
 		})
 	})
+	g.Describe("tfFmt", func() {
+		g.It("Should return correct fmt commands given the arguments", func() {
+			type args struct {
+				config Config
+			}
+
+			affirmative := true
+			negative := false
+
+			tests := []struct {
+				name string
+				args args
+				want *exec.Cmd
+			}{
+				{
+					"default",
+					args{config: Config{}},
+					exec.Command("terraform", "fmt"),
+				},
+				{
+					"with list",
+					args{config: Config{FmtOptions: FmtOptions{List: &affirmative}}},
+					exec.Command("terraform", "fmt", "-list=true"),
+				},
+				{
+					"with write",
+					args{config: Config{FmtOptions: FmtOptions{Write: &affirmative}}},
+					exec.Command("terraform", "fmt", "-write=true"),
+				},
+				{
+					"with diff",
+					args{config: Config{FmtOptions: FmtOptions{Diff: &affirmative}}},
+					exec.Command("terraform", "fmt", "-diff=true"),
+				},
+				{
+					"with check",
+					args{config: Config{FmtOptions: FmtOptions{Check: &affirmative}}},
+					exec.Command("terraform", "fmt", "-check=true"),
+				},
+				{
+					"with combination",
+					args{config: Config{FmtOptions: FmtOptions{
+						List:  &negative,
+						Write: &negative,
+						Diff:  &affirmative,
+						Check: &affirmative,
+					}}},
+					exec.Command("terraform", "fmt", "-list=false", "-write=false", "-diff=true", "-check=true"),
+				},
+			}
+
+			for _, tt := range tests {
+				g.Assert(tfFmt(tt.args.config)).Equal(tt.want)
+			}
+		})
+	})
 }