feat(runner): ensure terragrunt installation

internal/runner/runner.go

@@ -157,7 +157,7 @@ func (r *Runner) install() error {
 		r.exec = terraformExec
 	case "terragrunt":
 		log.Infof("using terragrunt")
-		r.exec = terragrunt.NewTerragrunt(terraformExec, configv1alpha1.GetTerragruntVersion(r.repository, r.layer), PlanArtifact)
+		r.exec = terragrunt.NewTerragrunt(terraformExec, configv1alpha1.GetTerragruntVersion(r.repository, r.layer), PlanArtifact, r.config.Runner.RunnerBinaryPath)
 	}
 	err := r.exec.Install()
 	if err != nil {

internal/runner/terragrunt/terragrunt.go

@@ -1,6 +1,7 @@
 package terragrunt
 
 import (
+	"crypto/sha256"
 	"errors"
 	"fmt"
 	"io"
@@ -9,27 +10,26 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strings"
 
 	"github.com/padok-team/burrito/internal/runner/terraform"
 )
 
-const (
-	BinWorkDir = "/runner/bin"
-)
-
 type Terragrunt struct {
 	execPath         string
 	planArtifactPath string
 	version          string
 	workingDir       string
 	terraform        *terraform.Terraform
+	runnerBinaryPath string
 }
 
-func NewTerragrunt(terraformExec *terraform.Terraform, terragruntVersion, planArtifactPath string) *Terragrunt {
+func NewTerragrunt(terraformExec *terraform.Terraform, terragruntVersion, planArtifactPath string, runnerBinaryPath string) *Terragrunt {
 	return &Terragrunt{
 		version:          terragruntVersion,
 		terraform:        terraformExec,
 		planArtifactPath: planArtifactPath,
+		runnerBinaryPath: runnerBinaryPath,
 	}
 }
 
@@ -43,7 +43,8 @@ func (t *Terragrunt) Install() error {
 	if err != nil {
 		return err
 	}
-	path, err := downloadTerragrunt(t.version)
+
+	path, err := ensureTerragrunt(t.version, t.runnerBinaryPath)
 	if err != nil {
 		return err
 	}
@@ -115,7 +116,79 @@ func (t *Terragrunt) Show(mode string) ([]byte, error) {
 	return output, nil
 }
 
-func downloadTerragrunt(version string) (string, error) {
+func ensureTerragrunt(version string, runnerBinaryPath string) (string, error) {
+	runnerBinary := filepath.Join(runnerBinaryPath, "terragrunt")
+	info, err := os.Stat(runnerBinary)
+	if !os.IsNotExist(err) && !info.IsDir() {
+		hash, err := calculateFileSHA256(runnerBinary)
+		if err != nil {
+			return "", err
+		}
+
+		trustedHash, err := getTerragruntSHA256(version)
+		if err != nil {
+			return "", err
+		}
+
+		if hash == trustedHash {
+			return filepath.Abs(runnerBinaryPath)
+		}
+	}
+
+	path, err := downloadTerragrunt(version, runnerBinaryPath)
+	if err != nil {
+		return "", err
+	}
+	return path, nil
+}
+
+func calculateFileSHA256(filename string) (string, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	hash := sha256.New()
+
+	if _, err := io.Copy(hash, file); err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%x", hash.Sum(nil)), nil
+}
+
+func getTerragruntSHA256(version string) (string, error) {
+	cpuArch := runtime.GOARCH
+	response, err := http.Get(fmt.Sprintf("https://github.com/gruntwork-io/terragrunt/releases/download/v%s/SHA256SUMS", version))
+	if err != nil {
+		return "", err
+	}
+	defer response.Body.Close()
+
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		return "", err
+	}
+
+	lines := strings.Split(string(body), "\n")
+	for _, line := range lines {
+		parts := strings.Fields(line)
+		if len(parts) != 2 {
+			continue
+		}
+		sha := parts[0]
+		filename := parts[1]
+
+		if strings.Contains(filename, fmt.Sprintf("linux_%s", cpuArch)) {
+			return sha, nil
+		}
+	}
+
+	return "", errors.New("could not find a hash for this architecture in SHA256SUMS file")
+}
+
+func downloadTerragrunt(version string, runnerBinaryPath string) (string, error) {
 	cpuArch := runtime.GOARCH
 
 	url := fmt.Sprintf("https://github.com/gruntwork-io/terragrunt/releases/download/v%s/terragrunt_linux_%s", version, cpuArch)
@@ -126,7 +199,7 @@ func downloadTerragrunt(version string) (string, error) {
 	}
 	defer response.Body.Close()
 
-	filename := fmt.Sprintf("%s/terragrunt_%s", BinWorkDir, cpuArch)
+	filename := fmt.Sprintf("%s/terragrunt_%s", runnerBinaryPath, cpuArch)
 	file, err := os.Create(filename)
 	if err != nil {
 		return "", err