terraform: check for errors initializing a provider

terraform/resource_provider.go

@@ -12,8 +12,8 @@ type ResourceProvider interface {
 	// Configure configures the provider itself with the configuration
 	// given. This is useful for setting things like access keys.
 	//
-	// Configure returns a list of warnings and a potential error.
-	Configure(config map[string]interface{}) ([]string, error)
+	// Configure returns an error if it occurred.
+	Configure(config map[string]interface{}) error
 
 	// Resources returns all the available resource types that this provider
 	// knows how to manage.

terraform/resource_provider_mock.go

@@ -8,7 +8,6 @@ type MockResourceProvider struct {
 
 	ConfigureCalled      bool
 	ConfigureConfig      map[string]interface{}
-	ConfigureReturnWarnings []string
 	ConfigureReturnError error
 	DiffCalled           bool
 	DiffState            *ResourceState
@@ -20,10 +19,10 @@ type MockResourceProvider struct {
 	ResourcesReturn      []ResourceType
 }
 
-func (p *MockResourceProvider) Configure(c map[string]interface{}) ([]string, error) {
+func (p *MockResourceProvider) Configure(c map[string]interface{}) error {
 	p.ConfigureCalled = true
 	p.ConfigureConfig = c
-	return p.ConfigureReturnWarnings, p.ConfigureReturnError
+	return p.ConfigureReturnError
 }
 
 func (p *MockResourceProvider) Diff(

terraform/terraform.go

@@ -134,7 +134,9 @@ func (t *Terraform) diffWalkFn(
 		}
 
 		// Initialize the provider if we haven't already
-		p.init(vars)
+		if err := p.init(vars); err != nil {
+			return err
+		}
 
 		l.RLock()
 		var rs *ResourceState
@@ -173,17 +175,15 @@ func (t *Terraform) diffWalkFn(
 	}
 }
 
-func (t *terraformProvider) init(vars map[string]string) error {
-	var err error
-
+func (t *terraformProvider) init(vars map[string]string) (err error) {
 	t.Once.Do(func() {
 		var c map[string]interface{}
 		if t.Config != nil {
 			c = t.Config.ReplaceVariables(vars).Config
 		}
 
-		_, err = t.Provider.Configure(c)
+		err = t.Provider.Configure(c)
 	})
 
-	return err
+	return
 }