Merge pull request #94 from caioquirino/parallel_execution

Added support for parallel execution

DOCS.md

@@ -196,6 +196,19 @@ pipeline:
 +     check: true
 ```
 
+You may want to run some executions in parallel without having racing condition problems with the .terraform dir and 
+plan's output file.
+
+```diff
+pipeline:
+  backend-service:
+    image: jmccann/drone-terraform:<version>
++   tf_data_dir: .backend-service.terraform
+  frontend-service:
+    image: jmccann/drone-terraform:<version>
++   tf_data_dir: .frontend-service.terraform
+```
+
 # Parameter Reference
 
 actions
@@ -253,3 +266,6 @@ root_dir
 
 parallelism
 : The number of concurrent operations as Terraform walks its graph.
+
+tf_data_dir
+: changes the location where Terraform keeps its per-working-directory data, such as the current remote backend configuration.

main.go

@@ -108,6 +108,11 @@ func main() {
 			Usage:  "a list of var files to use. Each value is passed as -var-file=<value>",
 			EnvVar: "PLUGIN_VAR_FILES",
 		},
+		cli.StringFlag{
+			Name:   "tf_data_dir",
+			Usage:  "changes the location where Terraform keeps its per-working-directory data, such as the current remote backend configuration",
+			EnvVar: "PLUGIN_TF_DATA_DIR",
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {
@@ -156,6 +161,7 @@ func run(c *cli.Context) error {
 			Parallelism:      c.Int("parallelism"),
 			Targets:          c.StringSlice("targets"),
 			VarFiles:         c.StringSlice("var_files"),
+			TerraformDataDir: c.String("tf_data_dir"),
 		},
 		Netrc: Netrc{
 			Login:    c.String("netrc.username"),

plugin.go

@@ -33,6 +33,7 @@ type (
 		Parallelism      int
 		Targets          []string
 		VarFiles         []string
+		TerraformDataDir string
 	}
 
 	// Netrc is credentials for cloning
@@ -86,6 +87,12 @@ func (p Plugin) Exec() error {
 		return err
 	}
 
+	var terraformDataDir string = ".terraform"
+	if p.Config.TerraformDataDir != "" {
+		terraformDataDir = p.Config.TerraformDataDir
+		os.Setenv("TF_DATA_DIR", p.Config.TerraformDataDir)
+	}
+
 	var commands []*exec.Cmd
 
 	commands = append(commands, exec.Command("terraform", "version"))
@@ -96,7 +103,7 @@ func (p Plugin) Exec() error {
 		commands = append(commands, installCaCert(p.Config.Cacert))
 	}
 
-	commands = append(commands, deleteCache())
+	commands = append(commands, deleteCache(terraformDataDir))
 	commands = append(commands, initCommand(p.Config.InitOptions))
 	commands = append(commands, getModules())
 
@@ -120,7 +127,7 @@ func (p Plugin) Exec() error {
 		}
 	}
 
-	commands = append(commands, deleteCache())
+	commands = append(commands, deleteCache(terraformDataDir))
 
 	for _, c := range commands {
 		if c.Dir == "" {
@@ -183,11 +190,11 @@ func assumeRole(roleArn string) {
 	os.Setenv("AWS_SESSION_TOKEN", value.SessionToken)
 }
 
-func deleteCache() *exec.Cmd {
+func deleteCache(terraformDataDir string) *exec.Cmd {
 	return exec.Command(
 		"rm",
 		"-rf",
-		".terraform",
+		terraformDataDir,
 	)
 }
 
@@ -253,7 +260,8 @@ func tfApply(config Config) *exec.Cmd {
 	if config.InitOptions.LockTimeout != "" {
 		args = append(args, fmt.Sprintf("-lock-timeout=%s", config.InitOptions.LockTimeout))
 	}
-	args = append(args, "plan.tfout")
+	args = append(args, getTfoutPath())
+
 	return exec.Command(
 		"terraform",
 		args...,
@@ -293,7 +301,7 @@ func tfPlan(config Config, destroy bool) *exec.Cmd {
 	if destroy {
 		args = append(args, "-destroy")
 	} else {
-		args = append(args, "-out=plan.tfout")
+		args = append(args, fmt.Sprintf("-out=%s", getTfoutPath()))
 	}
 
 	for _, v := range config.Targets {
@@ -354,6 +362,15 @@ func tfFmt(config Config) *exec.Cmd {
 	)
 }
 
+func getTfoutPath() string {
+	terraformDataDir := os.Getenv("TF_DATA_DIR")
+	if terraformDataDir == ".terraform" || terraformDataDir == "" {
+		return "plan.tfout"
+	} else {
+		return fmt.Sprintf("%s.plan.tfout", terraformDataDir)
+	}
+}
+
 func vars(vs map[string]string) []string {
 	var args []string
 	for k, v := range vs {

plugin_test.go

@@ -204,4 +204,42 @@ func TestPlugin(t *testing.T) {
 			}
 		})
 	})
+
+	g.Describe("tfDataDir", func() {
+		g.It("Should override the terraform data dir environment variable when provided", func() {
+			type args struct {
+				config Config
+			}
+
+			tests := []struct {
+				name string
+				args args
+				want *exec.Cmd
+			}{
+				{
+					"with TerraformDataDir",
+					args{config: Config{TerraformDataDir: ".overriden_terraform_dir"}},
+					exec.Command("terraform", "apply", ".overriden_terraform_dir.plan.tfout"),
+				},
+				{
+					"with TerraformDataDir value as .terraform",
+					args{config: Config{TerraformDataDir: ".terraform"}},
+					exec.Command("terraform", "apply", "plan.tfout"),
+				},
+				{
+					"without TerraformDataDir",
+					args{config: Config{}},
+					exec.Command("terraform", "apply", "plan.tfout"),
+				},
+			}
+
+			for _, tt := range tests {
+				os.Setenv("TF_DATA_DIR", tt.args.config.TerraformDataDir)
+				applied := tfApply(tt.args.config)
+
+				g.Assert(applied).Equal(tt.want)
+
+			}
+		})
+	})
 }