From 914636668a85d907889d0ce3684399a677326ce6 Mon Sep 17 00:00:00 2001
From: Mariano Cano <mariano@smallstep.com>
Date: Thu, 20 Feb 2020 15:48:48 -0800
Subject: [PATCH] Add support for loading templates without using files.

---
 templates/templates.go      | 33 +++++++++++++++++++++++----------
 templates/templates_test.go | 12 ++++++++++--
 2 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/templates/templates.go b/templates/templates.go
index cfd42e4c..b5920974 100644
--- a/templates/templates.go
+++ b/templates/templates.go
@@ -106,6 +106,7 @@ type Template struct {
 	TemplatePath string       `json:"template"`
 	Path         string       `json:"path"`
 	Comment      string       `json:"comment"`
+	Content      []byte       `json:"-"`
 }
 
 // Validate returns an error if the template is not valid.
@@ -117,10 +118,12 @@ func (t *Template) Validate() error {
 		return errors.New("template name cannot be empty")
 	case t.Type != Snippet && t.Type != File && t.Type != Directory:
 		return errors.Errorf("invalid template type %s, it must be %s, %s, or %s", t.Type, Snippet, File, Directory)
-	case t.TemplatePath == "" && t.Type != Directory:
+	case t.TemplatePath == "" && t.Type != Directory && len(t.Content) == 0:
 		return errors.New("template template cannot be empty")
 	case t.TemplatePath != "" && t.Type == Directory:
 		return errors.New("template template must be empty with directory type")
+	case t.TemplatePath != "" && len(t.Content) > 0:
+		return errors.New("template template must be empty with content")
 	case t.Path == "":
 		return errors.New("template path cannot be empty")
 	}
@@ -148,20 +151,30 @@ func (t *Template) Validate() error {
 // template fails.
 func (t *Template) Load() error {
 	if t.Template == nil && t.Type != Directory {
-		filename := config.StepAbs(t.TemplatePath)
-		b, err := ioutil.ReadFile(filename)
-		if err != nil {
-			return errors.Wrapf(err, "error reading %s", filename)
-		}
-		tmpl, err := template.New(t.Name).Funcs(sprig.TxtFuncMap()).Parse(string(b))
-		if err != nil {
-			return errors.Wrapf(err, "error parsing %s", filename)
+		switch {
+		case t.TemplatePath != "":
+			filename := config.StepAbs(t.TemplatePath)
+			b, err := ioutil.ReadFile(filename)
+			if err != nil {
+				return errors.Wrapf(err, "error reading %s", filename)
+			}
+			return t.LoadBytes(b)
+		default:
+			return t.LoadBytes(t.Content)
 		}
-		t.Template = tmpl
 	}
 	return nil
 }
 
+func (t *Template) LoadBytes(b []byte) error {
+	tmpl, err := template.New(t.Name).Funcs(sprig.TxtFuncMap()).Parse(string(b))
+	if err != nil {
+		return errors.Wrapf(err, "error parsing template %s", t.Name)
+	}
+	t.Template = tmpl
+	return nil
+}
+
 // Render executes the template with the given data and returns the rendered
 // version.
 func (t *Template) Render(data interface{}) ([]byte, error) {
diff --git a/templates/templates_test.go b/templates/templates_test.go
index c3d252ad..e00217c8 100644
--- a/templates/templates_test.go
+++ b/templates/templates_test.go
@@ -62,6 +62,12 @@ func TestSSHTemplates_Validate(t *testing.T) {
 	host := []Template{
 		{Name: "ca.tpl", Type: File, TemplatePath: "../authority/testdata/templates/ca.tpl", Path: "/etc/ssh/ca.pub", Comment: "#"},
 	}
+	content := []Template{
+		{Name: "test.tpl", Type: File, Content: []byte("some content"), Path: "/test.pub", Comment: "#"},
+	}
+	badContent := []Template{
+		{Name: "ca.tpl", Type: File, TemplatePath: "../authority/testdata/templates/ca.tpl", Content: []byte("some content"), Path: "/etc/ssh/ca.pub", Comment: "#"},
+	}
 
 	type fields struct {
 		User []Template
@@ -75,8 +81,10 @@ func TestSSHTemplates_Validate(t *testing.T) {
 		{"ok", fields{user, host}, false},
 		{"user", fields{user, nil}, false},
 		{"host", fields{nil, host}, false},
+		{"content", fields{content, nil}, false},
 		{"badUser", fields{[]Template{{}}, nil}, true},
 		{"badHost", fields{nil, []Template{{}}}, true},
+		{"badContent", fields{badContent, nil}, true},
 	}
 	var nilValue *SSHTemplates
 	assert.NoError(t, nilValue.Validate())
@@ -163,8 +171,8 @@ func TestLoadAll(t *testing.T) {
 		{"ok", args{tmpl}, false},
 		{"empty", args{&Templates{}}, false},
 		{"nil", args{nil}, false},
-		{"badUser", args{&Templates{SSH: &SSHTemplates{User: []Template{{}}}}}, true},
-		{"badHost", args{&Templates{SSH: &SSHTemplates{Host: []Template{{}}}}}, true},
+		{"badUser", args{&Templates{SSH: &SSHTemplates{User: []Template{{TemplatePath: "missing"}}}}}, true},
+		{"badHost", args{&Templates{SSH: &SSHTemplates{Host: []Template{{TemplatePath: "missing"}}}}}, true},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {