diff --git a/plugin_test.go b/plugin_test.go
index 4159d49..fb57da2 100644
--- a/plugin_test.go
+++ b/plugin_test.go
@@ -1,279 +1,411 @@
 package main
 
 import (
+	"fmt"
+	"io/ioutil"
 	"os"
 	"os/exec"
-	"testing"
+	"os/user"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"time"
 
-	. "github.com/franela/goblin"
+	"github.com/Sirupsen/logrus"
+	"github.com/aws/aws-sdk-go/aws/credentials"
+	"github.com/aws/aws-sdk-go/aws/credentials/stscreds"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/sts"
 )
 
-func TestPlugin(t *testing.T) {
-	g := Goblin(t)
+type (
+	// Config holds input parameters for the plugin
+	Config struct {
+		Actions          []string
+		Vars             map[string]string
+		Secrets          map[string]string
+		InitOptions      InitOptions
+		FmtOptions       FmtOptions
+		Cacert           string
+		Sensitive        bool
+		RoleARN          string
+		RootDir          string
+		Parallelism      int
+		Targets          []string
+		VarFiles         []string
+		TerraformDataDir string
+	}
 
-	g.Describe("CopyTfEnv", func() {
-		g.It("Should create copies of TF_VAR_ to lowercase", func() {
-			// Set some initial TF_VAR_ that are uppercase
-			os.Setenv("TF_VAR_SOMETHING", "some value")
-			os.Setenv("TF_VAR_SOMETHING_ELSE", "some other value")
-			os.Setenv("TF_VAR_BASE64", "dGVzdA==")
+	// Netrc is credentials for cloning
+	Netrc struct {
+		Machine  string
+		Login    string
+		Password string
+	}
 
-			CopyTfEnv()
+	// InitOptions include options for the Terraform's init command
+	InitOptions struct {
+		BackendConfig []string `json:"backend-config"`
+		Lock          *bool    `json:"lock"`
+		LockTimeout   string   `json:"lock-timeout"`
+	}
 
-			// Make sure new env vars exist with proper values
-			g.Assert(os.Getenv("TF_VAR_something")).Equal("some value")
-			g.Assert(os.Getenv("TF_VAR_something_else")).Equal("some other value")
-			g.Assert(os.Getenv("TF_VAR_base64")).Equal("dGVzdA==")
-		})
-	})
+	// 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"`
+	}
 
-	g.Describe("tfApply", func() {
-		g.It("Should return correct apply commands given the arguments", func() {
-			type args struct {
-				config Config
+	// Plugin represents the plugin instance to be executed
+	Plugin struct {
+		Config    Config
+		Netrc     Netrc
+		Terraform Terraform
+	}
+)
+
+// Exec executes the plugin
+func (p Plugin) Exec() error {
+	// Install specified version of terraform
+	if p.Terraform.Version != "" {
+		err := installTerraform(p.Terraform.Version)
+
+		if err != nil {
+			return err
+		}
+	}
+
+	if p.Config.RoleARN != "" {
+		assumeRole(p.Config.RoleARN)
+	}
+
+	// writing the .netrc file with Github credentials in it.
+	err := writeNetrc(p.Netrc.Machine, p.Netrc.Login, p.Netrc.Password)
+	if err != nil {
+		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"))
+
+	CopyTfEnv()
+
+	if p.Config.Cacert != "" {
+		commands = append(commands, installCaCert(p.Config.Cacert))
+	}
+
+	commands = append(commands, deleteCache(terraformDataDir))
+	commands = append(commands, initCommand(p.Config.InitOptions))
+	commands = append(commands, getModules())
+
+	// 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())
+		case "plan":
+			commands = append(commands, tfPlan(p.Config, false))
+		case "plan-destroy":
+			commands = append(commands, tfPlan(p.Config, true))
+		case "apply":
+			commands = append(commands, tfApply(p.Config))
+		case "destroy":
+			commands = append(commands, tfDestroy(p.Config))
+		default:
+			return fmt.Errorf("valid actions are: fmt, validate, plan, apply, plan-destroy, destroy.  You provided %s", action)
+		}
+	}
+
+	commands = append(commands, deleteCache(terraformDataDir))
+
+	for _, c := range commands {
+		if c.Dir == "" {
+			wd, err := os.Getwd()
+			if err == nil {
+				c.Dir = wd
 			}
+		}
+		if p.Config.RootDir != "" {
+			c.Dir = c.Dir + "/" + p.Config.RootDir
+		}
+		c.Stdout = os.Stdout
+		c.Stderr = os.Stderr
+		if !p.Config.Sensitive {
+			trace(c)
+		}
 
-			tests := []struct {
-				name string
-				args args
-				want *exec.Cmd
-			}{
-				{
-					"default",
-					args{config: Config{}},
-					exec.Command("terraform", "apply", "plan.tfout"),
-				},
-				{
-					"with parallelism",
-					args{config: Config{Parallelism: 5}},
-					exec.Command("terraform", "apply", "-parallelism=5", "plan.tfout"),
-				},
-				{
-					"with targets",
-					args{config: Config{Targets: []string{"target1", "target2"}}},
-					exec.Command("terraform", "apply", "--target", "target1", "--target", "target2", "plan.tfout"),
-				},
-			}
+		err := c.Run()
+		if err != nil {
+			logrus.WithFields(logrus.Fields{
+				"error": err,
+			}).Fatal("Failed to execute a command")
+		}
+		logrus.Debug("Command completed successfully")
+	}
 
-			for _, tt := range tests {
-				g.Assert(tfApply(tt.args.config)).Equal(tt.want)
-			}
-		})
-	})
-
-	g.Describe("tfDestroy", func() {
-		g.It("Should return correct destroy commands given the arguments", func() {
-			type args struct {
-				config Config
-			}
-
-			tests := []struct {
-				name string
-				args args
-				want *exec.Cmd
-			}{
-				{
-					"default",
-					args{config: Config{}},
-					exec.Command("terraform", "destroy", "-force"),
-				},
-				{
-					"with parallelism",
-					args{config: Config{Parallelism: 5}},
-					exec.Command("terraform", "destroy", "-parallelism=5", "-force"),
-				},
-				{
-					"with targets",
-					args{config: Config{Targets: []string{"target1", "target2"}}},
-					exec.Command("terraform", "destroy", "-target=target1", "-target=target2", "-force"),
-				},
-				{
-					"with vars",
-					args{config: Config{Vars: map[string]string{"username": "someuser", "password": "1pass"}}},
-					exec.Command("terraform", "destroy", "-var", "username=someuser", "-var", "password=1pass", "-force"),
-				},
-				{
-					"with var-files",
-					args{config: Config{VarFiles: []string{"common.tfvars", "prod.tfvars"}}},
-					exec.Command("terraform", "destroy", "-var-file=common.tfvars", "-var-file=prod.tfvars", "-force"),
-				},
-			}
-
-			for _, tt := range tests {
-				g.Assert(tfDestroy(tt.args.config)).Equal(tt.want)
-			}
-		})
-	})
-	
-	g.Describe("tfValidate", func() {
-		g.It("Should return correct validate command", func() {
-			type args struct {
-				config Config
-			}
-
-			tests := []struct {
-				name string
-				args args
-				want *exec.Cmd
-			}{
-				{
-					"default",
-					args{config: Config{VarFiles: []string{"common.tfvars", "prod.tfvars"}}},
-					exec.Command("terraform", "validate"),
-				},
-				{
-					"with no vars",
-					args{config: Config{Vars: map[string]string{"var1": "value1", "var2": "value2"}}},
-					exec.Command("terraform", "validate"),
-				},
-				{
-					"with no var-files",
-					args{config: Config{VarFiles: []string{"common.tfvars", "prod.tfvars"}}},
-					exec.Command("terraform", "validate"),
-				},
-			}
-
-			for _, tt := range tests {
-				g.Assert(tfValidate()).Equal(tt.want)
-			}
-		})
-	})
-
-	g.Describe("tfPlan", func() {
-		g.It("Should return correct plan commands given the arguments", func() {
-			type args struct {
-				config Config
-			}
-
-			tests := []struct {
-				name    string
-				args    args
-				destroy bool
-				want    *exec.Cmd
-			}{
-				{
-					"default",
-					args{config: Config{}},
-					false,
-					exec.Command("terraform", "plan", "-out=plan.tfout"),
-				},
-				{
-					"destroy",
-					args{config: Config{}},
-					true,
-					exec.Command("terraform", "plan", "-destroy"),
-				},
-				{
-					"with vars",
-					args{config: Config{Vars: map[string]string{"username": "someuser", "password": "1pass"}}},
-					false,
-					exec.Command("terraform", "plan", "-out=plan.tfout", "-var", "username=someuser", "-var", "password=1pass"),
-				},
-				{
-					"with var-files",
-					args{config: Config{VarFiles: []string{"common.tfvars", "prod.tfvars"}}},
-					false,
-					exec.Command("terraform", "plan", "-out=plan.tfout", "-var-file=common.tfvars", "-var-file=prod.tfvars"),
-				},
-			}
-
-			for _, tt := range tests {
-				g.Assert(tfPlan(tt.args.config, tt.destroy)).Equal(tt.want)
-			}
-		})
-	})
-	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)
-			}
-		})
-	})
-
-	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)
-
-			}
-		})
-	})
+	return nil
 }
+
+// CopyTfEnv creates copies of TF_VAR_ to lowercase
+func CopyTfEnv() {
+	tfVar := regexp.MustCompile(`^TF_VAR_.*$`)
+	for _, e := range os.Environ() {
+		pair := strings.SplitN(e, "=", 2)
+		if tfVar.MatchString(pair[0]) {
+			name := strings.Split(pair[0], "TF_VAR_")
+			os.Setenv(fmt.Sprintf("TF_VAR_%s", strings.ToLower(name[1])), pair[1])
+		}
+	}
+}
+
+func assumeRole(roleArn string) {
+	client := sts.New(session.New())
+	duration := time.Hour * 1
+	stsProvider := &stscreds.AssumeRoleProvider{
+		Client:          client,
+		Duration:        duration,
+		RoleARN:         roleArn,
+		RoleSessionName: "drone",
+	}
+
+	value, err := credentials.NewCredentials(stsProvider).Get()
+	if err != nil {
+		logrus.WithFields(logrus.Fields{
+			"error": err,
+		}).Fatal("Error assuming role!")
+	}
+	os.Setenv("AWS_ACCESS_KEY_ID", value.AccessKeyID)
+	os.Setenv("AWS_SECRET_ACCESS_KEY", value.SecretAccessKey)
+	os.Setenv("AWS_SESSION_TOKEN", value.SessionToken)
+}
+
+func deleteCache(terraformDataDir string) *exec.Cmd {
+	return exec.Command(
+		"rm",
+		"-rf",
+		terraformDataDir,
+	)
+}
+
+func getModules() *exec.Cmd {
+	return exec.Command(
+		"terraform",
+		"get",
+	)
+}
+
+func initCommand(config InitOptions) *exec.Cmd {
+	args := []string{
+		"init",
+	}
+
+	for _, v := range config.BackendConfig {
+		args = append(args, fmt.Sprintf("-backend-config=%s", v))
+	}
+
+	// True is default in TF
+	if config.Lock != nil {
+		args = append(args, fmt.Sprintf("-lock=%t", *config.Lock))
+	}
+
+	// "0s" is default in TF
+	if config.LockTimeout != "" {
+		args = append(args, fmt.Sprintf("-lock-timeout=%s", config.LockTimeout))
+	}
+
+	// Fail Terraform execution on prompt
+	args = append(args, "-input=false")
+
+	return exec.Command(
+		"terraform",
+		args...,
+	)
+}
+
+func installCaCert(cacert string) *exec.Cmd {
+	ioutil.WriteFile("/usr/local/share/ca-certificates/ca_cert.crt", []byte(cacert), 0644)
+	return exec.Command(
+		"update-ca-certificates",
+	)
+}
+
+func trace(cmd *exec.Cmd) {
+	fmt.Println("$", strings.Join(cmd.Args, " "))
+}
+
+func tfApply(config Config) *exec.Cmd {
+	args := []string{
+		"apply",
+	}
+	for _, v := range config.Targets {
+		args = append(args, "--target", fmt.Sprintf("%s", v))
+	}
+	if config.Parallelism > 0 {
+		args = append(args, fmt.Sprintf("-parallelism=%d", config.Parallelism))
+	}
+	if config.InitOptions.Lock != nil {
+		args = append(args, fmt.Sprintf("-lock=%t", *config.InitOptions.Lock))
+	}
+	if config.InitOptions.LockTimeout != "" {
+		args = append(args, fmt.Sprintf("-lock-timeout=%s", config.InitOptions.LockTimeout))
+	}
+	args = append(args, getTfoutPath())
+
+	return exec.Command(
+		"terraform",
+		args...,
+	)
+}
+
+func tfDestroy(config Config) *exec.Cmd {
+	args := []string{
+		"destroy",
+	}
+	for _, v := range config.Targets {
+		args = append(args, fmt.Sprintf("-target=%s", v))
+	}
+	args = append(args, varFiles(config.VarFiles)...)
+	args = append(args, vars(config.Vars)...)
+	if config.Parallelism > 0 {
+		args = append(args, fmt.Sprintf("-parallelism=%d", config.Parallelism))
+	}
+	if config.InitOptions.Lock != nil {
+		args = append(args, fmt.Sprintf("-lock=%t", *config.InitOptions.Lock))
+	}
+	if config.InitOptions.LockTimeout != "" {
+		args = append(args, fmt.Sprintf("-lock-timeout=%s", config.InitOptions.LockTimeout))
+	}
+	args = append(args, "-force")
+	return exec.Command(
+		"terraform",
+		args...,
+	)
+}
+
+func tfPlan(config Config, destroy bool) *exec.Cmd {
+	args := []string{
+		"plan",
+	}
+
+	if destroy {
+		args = append(args, "-destroy")
+	} else {
+		args = append(args, fmt.Sprintf("-out=%s", getTfoutPath()))
+	}
+
+	for _, v := range config.Targets {
+		args = append(args, "--target", fmt.Sprintf("%s", v))
+	}
+	args = append(args, varFiles(config.VarFiles)...)
+	args = append(args, vars(config.Vars)...)
+	if config.Parallelism > 0 {
+		args = append(args, fmt.Sprintf("-parallelism=%d", config.Parallelism))
+	}
+	if config.InitOptions.Lock != nil {
+		args = append(args, fmt.Sprintf("-lock=%t", *config.InitOptions.Lock))
+	}
+	if config.InitOptions.LockTimeout != "" {
+		args = append(args, fmt.Sprintf("-lock-timeout=%s", config.InitOptions.LockTimeout))
+	}
+	return exec.Command(
+		"terraform",
+		args...,
+	)
+}
+
+func tfValidate() *exec.Cmd {
+	args := []string{
+		"validate",
+	}
+	return exec.Command(
+		"terraform",
+		args...,
+	)
+}
+
+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 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 {
+		args = append(args, "-var", fmt.Sprintf("%s=%s", k, v))
+	}
+	return args
+}
+
+func varFiles(vfs []string) []string {
+	var args []string
+	for _, v := range vfs {
+		args = append(args, fmt.Sprintf("-var-file=%s", v))
+	}
+	return args
+}
+
+// helper function to write a netrc file.
+// The following code comes from the official Git plugin for Drone:
+// https://github.com/drone-plugins/drone-git/blob/8386effd2fe8c8695cf979427f8e1762bd805192/utils.go#L43-L68
+func writeNetrc(machine, login, password string) error {
+	if machine == "" {
+		return nil
+	}
+	out := fmt.Sprintf(
+		netrcFile,
+		machine,
+		login,
+		password,
+	)
+
+	home := "/root"
+	u, err := user.Current()
+	if err == nil {
+		home = u.HomeDir
+	}
+	path := filepath.Join(home, ".netrc")
+	return ioutil.WriteFile(path, []byte(out), 0600)
+}
+
+const netrcFile = `
+machine %s
+login %s
+password %s
+`