terraform: allow skip provisioner test and proper error

.github/workflows/test.yml

@@ -18,5 +18,11 @@ jobs:
     - name: Checkout code
       uses: actions/checkout@v2
 
+    - name: Allow skip provisioner tests
+      uses: allenevans/set-env@v1.0.0
+      if: matrix.os != 'ubuntu-latest'
+      with:
+        ALLOW_PROVISIONER_SKIP: 1
+        
     - name: Test
       run: go test ./...

starlark/types/provider_test.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	stdos "os"
 	"testing"
 
 	"github.com/mcuadros/ascode/starlark/module/os"
@@ -33,6 +34,10 @@ func TestProvider(t *testing.T) {
 }
 
 func TestProvisioner(t *testing.T) {
+	if stdos.Getenv("ALLOW_PROVISIONER_SKIP") != "" && !terraform.IsTerraformBinaryAvailable() {
+		t.Skip("terraform binary now available in $PATH")
+	}
+
 	doTest(t, "testdata/provisioner.star")
 }
 

terraform/plugins.go

@@ -1,6 +1,7 @@
 package terraform
 
 import (
+	"fmt"
 	"os"
 	"os/exec"
 	"strings"
@@ -42,6 +43,10 @@ func (m *PluginManager) Provider(provider, version string, forceLocal bool) (*pl
 // try to locate it at the local Path, if not try to execute it from the
 // built-in plugins in the terraform binary.
 func (m *PluginManager) Provisioner(provisioner string) (*plugin.Client, discovery.PluginMeta, error) {
+	if !IsTerraformBinaryAvailable() {
+		return nil, discovery.PluginMeta{}, ErrTerraformNotAvailable
+	}
+
 	meta, ok := m.getLocal("provisioner", provisioner, "")
 	if ok {
 		return client(meta), meta, nil
@@ -121,3 +126,17 @@ func (m *PluginManager) getLocal(kind, provider, version string) (discovery.Plug
 
 	return set.Newest(), true
 }
+
+// ErrTerraformNotAvailable error used when `terraform` binary in not in the
+// path and we try to use a provisioner.
+var ErrTerraformNotAvailable = fmt.Errorf("provisioner error: executable file 'terraform' not found in $PATH")
+
+// IsTerraformBinaryAvailable determines if Terraform binary is available in
+// the path of the system. Terraform binary is a requirement for executing
+// provisioner plugins, since they are built-in on the Terrafrom binary. :(
+//
+// https://github.com/hashicorp/terraform/issues/20896#issuecomment-479054649
+func IsTerraformBinaryAvailable() bool {
+	_, err := exec.LookPath("terraform")
+	return err == nil
+}

terraform/plugins_test.go

@@ -3,6 +3,7 @@ package terraform
 import (
 	"fmt"
 	"io/ioutil"
+	"os"
 	"strings"
 	"testing"
 
@@ -51,6 +52,10 @@ func TestPluginManager_ProviderDefault(t *testing.T) {
 }
 
 func TestPluginManager_ProvisionerDefault(t *testing.T) {
+	if os.Getenv("ALLOW_PROVISIONER_SKIP") != "" && !IsTerraformBinaryAvailable() {
+		t.Skip("terraform binary now available in $PATH")
+	}
+
 	path, err := ioutil.TempDir("", "provisioner")
 	assert.NoError(t, err)