Add templating for var-file names

Signed-off-by: Reinhard Naegele <unguiculus@gmail.com>

README.md

@@ -41,7 +41,7 @@ By default, `gotf.yaml` is loaded from the current directory.
 varsFiles:
   # tfvars files are added to the Terraform environment via
   # TF_CLI_ARGS_<command>=-var-file=<file> for commands that support them
-  - testmodule/test.tfvars
+  - testmodule/test-{{ .Params.env }}.tfvars
 vars:
   # Variables are added to the Terraform environment via
   # TF_VAR_<var>=value for commands that support them
@@ -75,7 +75,7 @@ backendConfigs:
 
 Go templating can be used in the config file as follows.
 
-* In the first templating pass, `vars` and `envs` are processed.
+* In the first templating pass, `varsFiles`, `vars`, and `envs` are processed.
   All parameters specified using the `-p|--param` flag are available in the `.Params` object.
 * In the second templating pass, `backendConfigs` are processed.
   `vars` are available as `.Vars`, `envs` are available as `.Envs` with the results from the first templating pass.
@@ -93,7 +93,7 @@ After processing, the config file would look like this:
 varsFiles:
   # tfvars files are added to the Terraform environment via
   # TF_CLI_ARGS_<command>=-var-file=<file> for commands that support them
-  - testmodule/test.tfvars
+  - testmodule/test-prod.tfvars
 vars:
   # Variables are added to the Terraform environment via
   # TF_VAR_<var>=value for commands that support them

pkg/config/config.go

@@ -42,16 +42,22 @@ func Load(configFile string, params map[string]string) (*Config, error) {
 		return nil, err
 	}
 
+	templatingInput := map[string]interface{}{
+		"Params": params,
+	}
+
 	cfgFileDir := filepath.Dir(configFile)
 	for i, f := range cfg.VarsFiles {
+		sb := strings.Builder{}
+		err := renderTemplate(&sb, templatingInput, f)
+		if err != nil {
+			return nil, err
+		}
+		varFile := sb.String()
 		if !filepath.IsAbs(f) {
-			varFile := filepath.Join(cfgFileDir, f)
-			cfg.VarsFiles[i] = varFile
+			varFile = filepath.Join(cfgFileDir, varFile)
 		}
-	}
-
-	templatingInput := map[string]interface{}{
-		"Params": params,
+		cfg.VarsFiles[i] = varFile
 	}
 
 	for key, value := range cfg.Vars {

pkg/config/config_test.go

@@ -21,13 +21,25 @@ import (
 )
 
 func TestLoad(t *testing.T) {
-	got, err := Load("testdata/test_config.yaml", map[string]string{"param": "paramvalue"})
+	got, err := Load("testdata/test_config.yaml", map[string]string{
+		"param": "paramvalue",
+		"env":   "prod",
+	})
 	assert.NoError(t, err)
-	assert.NotNil(t, got)
 
-	assert.Equal(t, got.VarsFiles, []string{"testdata/testmodule/test.tfvars"})
-	assert.Equal(t, got.Vars, map[string]string{"foo": "foovalue", "templatedVar": "paramvalue", "mapvar": "{\n  value1 = \"testvalue\"\n  value2 = true\n}"})
-	assert.Equal(t, got.Envs, map[string]string{"BAR": "barvalue", "TEMPLATED_ENV": "paramvalue"})
+	assert.Equal(t, got.VarsFiles, []string{
+		"testdata/testmodule/test1-prod.tfvars",
+		"testdata/testmodule/test2-prod.tfvars",
+	})
+	assert.Equal(t, got.Vars, map[string]string{
+		"foo":          "foovalue",
+		"templatedVar": "paramvalue",
+		"mapvar":       "{\n  value1 = \"testvalue\"\n  value2 = true\n}",
+	})
+	assert.Equal(t, got.Envs, map[string]string{
+		"BAR":           "barvalue",
+		"TEMPLATED_ENV": "paramvalue",
+	})
 	assert.Equal(t, got.BackendConfigs, map[string]string{
 		"backend_key":                  "be_key_foovalue_barvalue",
 		"backend_storage_account_name": "be_storage_account_name_foovalue_barvalue",

pkg/config/testdata/test_config.yaml

@@ -1,5 +1,6 @@
 varsFiles:
-  - testmodule/test.tfvars
+  - testmodule/test1-{{ .Params.env }}.tfvars
+  - testmodule/test2-{{ .Params.env }}.tfvars
 vars:
   foo: foovalue
   templatedVar: "{{ .Params.param }}"

pkg/config/testdata/testmodule/test.tf

@@ -4,6 +4,8 @@ terraform {
 
 variable "foo" {}
 
+variable "bar" {}
+
 variable "baz" {}
 
 variable "mapvar" {

pkg/config/testdata/testmodule/test1-prod.tfvars

@@ -0,0 +1 @@
+bar = "barvalue"

pkg/opts/opts.go

@@ -41,7 +41,7 @@ func (o *MapOpts) String() string {
 }
 
 func (o *MapOpts) Type() string {
-	return "map"
+	return "key=value"
 }
 
 func NewMapOpts() *MapOpts {

test/integration_test.go

@@ -37,18 +37,18 @@ func Test_e2e(t *testing.T) {
 
 	binary := buildBinary(tempDir)
 
-	output, err := runProcess(binary, "-d", "-c", "testdata/test_config.yaml", "init", "-no-color", "testdata/testmodule")
+	output, err := runProcess(binary, "-d", "-c", "testdata/test_config.yaml", "-p", "env=prod", "init", "-no-color", "testdata/testmodule")
 	fmt.Println(output)
 	assert.NoError(t, err)
 	assert.Contains(t, output, "Terraform has been successfully initialized!")
 
-	output, err = runProcess(binary, "-d", "-c", "testdata/test_config.yaml", "plan", "-no-color", "testdata/testmodule")
+	output, err = runProcess(binary, "-d", "-c", "testdata/test_config.yaml", "-p", "env=prod", "plan", "-no-color", "testdata/testmodule")
 	fmt.Println(output)
 	assert.NoError(t, err)
 	assert.Contains(t, output, "# null_resource.echo will be created")
 	assert.Contains(t, output, "Plan: 1 to add, 0 to change, 0 to destroy.")
 
-	output, err = runProcess(binary, "-d", "-c", "testdata/test_config.yaml", "apply", "-auto-approve", "-no-color", "testdata/testmodule")
+	output, err = runProcess(binary, "-d", "-c", "testdata/test_config.yaml", "-p", "env=prod", "apply", "-auto-approve", "-no-color", "testdata/testmodule")
 	fmt.Println(output)
 	assert.NoError(t, err)
 	assert.Contains(t, output, `baz = bazvalue

test/testdata/test_config.yaml

@@ -1,5 +1,5 @@
 varsFiles:
-  - testmodule/test.tfvars
+  - testmodule/test-{{ .Params.env }}.tfvars
 vars:
   foo: 42
   mapvar: |-

test/testdata/testmodule/test.tf

@@ -4,6 +4,8 @@ terraform {
 
 variable "foo" {}
 
+variable "bar" {}
+
 variable "baz" {}
 
 variable "mapvar" {}