certificates/templates/templates.go

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package templates
import (
"bytes"
"io/ioutil"
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"os"
"path/filepath"
"strings"
"text/template"
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"github.com/Masterminds/sprig/v3"
"github.com/pkg/errors"
"go.step.sm/cli-utils/fileutil"
"go.step.sm/cli-utils/step"
)
// TemplateType defines how a template will be written in disk.
type TemplateType string
const (
// Snippet will mark a template as a part of a file.
Snippet TemplateType = "snippet"
// PrependLine is a template for prepending a single line to a file. If the
// line already exists in the file it will be removed first.
PrependLine TemplateType = "prepend-line"
// File will mark a templates as a full file.
File TemplateType = "file"
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// Directory will mark a template as a directory.
Directory TemplateType = "directory"
)
// Templates is a collection of templates and variables.
type Templates struct {
SSH *SSHTemplates `json:"ssh,omitempty"`
Data map[string]interface{} `json:"data,omitempty"`
}
// Validate returns an error if a template is not valid.
func (t *Templates) Validate() (err error) {
if t == nil {
return nil
}
// Validate members
if err = t.SSH.Validate(); err != nil {
return
}
// Do not allow "Step" and "User"
if t.Data != nil {
if _, ok := t.Data["Step"]; ok {
return errors.New("templates variables cannot contain 'Step' as a property")
}
if _, ok := t.Data["User"]; ok {
return errors.New("templates variables cannot contain 'User' as a property")
}
}
return nil
}
// LoadAll preloads all templates in memory. It returns an error if an error is
// found parsing at least one template.
func LoadAll(t *Templates) (err error) {
if t != nil {
if t.SSH != nil {
for _, tt := range t.SSH.User {
if err = tt.Load(); err != nil {
return
}
}
for _, tt := range t.SSH.Host {
if err = tt.Load(); err != nil {
return
}
}
}
}
return
}
// SSHTemplates contains the templates defining ssh configuration files.
type SSHTemplates struct {
User []Template `json:"user"`
Host []Template `json:"host"`
}
// Validate returns an error if a template is not valid.
func (t *SSHTemplates) Validate() (err error) {
if t == nil {
return nil
}
for _, tt := range t.User {
if err = tt.Validate(); err != nil {
return
}
}
for _, tt := range t.Host {
if err = tt.Validate(); err != nil {
return
}
}
return
}
// Template represents a template file.
type Template struct {
*template.Template
Name string `json:"name"`
Type TemplateType `json:"type"`
TemplatePath string `json:"template"`
Path string `json:"path"`
Comment string `json:"comment"`
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RequiredData []string `json:"requires,omitempty"`
Content []byte `json:"-"`
}
// Validate returns an error if the template is not valid.
func (t *Template) Validate() error {
switch {
case t == nil:
return nil
case t.Name == "":
return errors.New("template name cannot be empty")
case t.Type != Snippet && t.Type != File && t.Type != Directory && t.Type != PrependLine:
return errors.Errorf("invalid template type %s, it must be %s, %s, %s, or %s", t.Type, Snippet, PrependLine, File, 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")
}
if t.TemplatePath != "" {
// Check for file
st, err := os.Stat(step.Abs(t.TemplatePath))
if err != nil {
return errors.Wrapf(err, "error reading %s", t.TemplatePath)
}
if st.IsDir() {
return errors.Errorf("error reading %s: is not a file", t.TemplatePath)
}
// Defaults
if t.Comment == "" {
t.Comment = "#"
}
}
return nil
}
// ValidateRequiredData checks that the given data contains all the keys
// required.
func (t *Template) ValidateRequiredData(data map[string]string) error {
for _, key := range t.RequiredData {
if _, ok := data[key]; !ok {
return errors.Errorf("required variable '%s' is missing", key)
}
}
return nil
}
// Load loads the template in memory, returns an error if the parsing of the
// template fails.
func (t *Template) Load() error {
if t.Template == nil && t.Type != Directory {
switch {
case t.TemplatePath != "":
filename := step.Abs(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)
}
}
return nil
}
// LoadBytes loads the template in memory, returns an error if the parsing of
// the template fails.
func (t *Template) LoadBytes(b []byte) error {
t.backfill(b)
tmpl, err := template.New(t.Name).Funcs(StepFuncMap()).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) {
if t.Type == Directory {
return nil, nil
}
if err := t.Load(); err != nil {
return nil, err
}
buf := new(bytes.Buffer)
if err := t.Execute(buf, data); err != nil {
return nil, errors.Wrapf(err, "error executing %s", t.TemplatePath)
}
return buf.Bytes(), nil
}
// Output renders the template and returns a template.Output struct or an error.
func (t *Template) Output(data interface{}) (Output, error) {
b, err := t.Render(data)
if err != nil {
return Output{}, err
}
return Output{
Name: t.Name,
Type: t.Type,
Path: t.Path,
Comment: t.Comment,
Content: b,
}, nil
}
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// backfill updates old templates with the required data.
func (t *Template) backfill(b []byte) {
if strings.EqualFold(t.Name, "sshd_config.tpl") && len(t.RequiredData) == 0 {
a := bytes.TrimSpace(b)
b := bytes.TrimSpace([]byte(DefaultSSHTemplateData[t.Name]))
if bytes.Equal(a, b) {
t.RequiredData = []string{"Certificate", "Key"}
}
}
}
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// Output represents the text representation of a rendered template.
type Output struct {
Name string `json:"name"`
Type TemplateType `json:"type"`
Path string `json:"path"`
Comment string `json:"comment"`
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Content []byte `json:"content"`
}
// Write writes the Output to the filesystem as a directory, file or snippet.
func (o *Output) Write() error {
// Replace ${STEPPATH} with the base step path.
o.Path = strings.Replace(o.Path, "${STEPPATH}", step.BasePath(), -1)
path := step.Abs(o.Path)
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if o.Type == Directory {
return mkdir(path, 0700)
}
dir := filepath.Dir(path)
if err := mkdir(dir, 0700); err != nil {
return err
}
switch o.Type {
case File:
return fileutil.WriteFile(path, o.Content, 0600)
case Snippet:
return fileutil.WriteSnippet(path, o.Content, 0600)
case PrependLine:
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return fileutil.PrependLine(path, o.Content, 0600)
default:
// Default to using a Snippet type if the type is not known.
return fileutil.WriteSnippet(path, o.Content, 0600)
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}
}
func mkdir(path string, perm os.FileMode) error {
if err := os.MkdirAll(path, perm); err != nil {
return errors.Wrapf(err, "error creating %s", path)
}
return nil
}
// StepFuncMap returns sprig.TxtFuncMap but removing the "env" and "expandenv"
// functions to avoid any leak of information.
func StepFuncMap() template.FuncMap {
m := sprig.TxtFuncMap()
delete(m, "env")
delete(m, "expandenv")
return m
}