package templates import ( "bytes" "io/ioutil" "text/template" "github.com/Masterminds/sprig" "github.com/pkg/errors" ) // 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" // File will mark a templates as a full file. File TemplateType = "file" ) // Output represents the text representation of a rendered template. type Output struct { Name string `json:"name"` Type TemplateType `json:"type"` Comment string `json:"comment"` Path string `json:"path"` Content []byte `json:"content"` } // 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.SSH != nil { for _, tt := range t.SSH.User { if err = tt.Load(); err != nil { return err } } for _, tt := range t.SSH.Host { if err = tt.Load(); err != nil { return err } } } return nil } // 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 on 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"` } // 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.TemplatePath == "": return errors.New("template template cannot be empty") case t.Path == "": return errors.New("template path cannot be empty") } // Defaults if t.Type == "" { t.Type = Snippet } if t.Comment == "" { t.Comment = "#" } 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 { b, err := ioutil.ReadFile(t.TemplatePath) if err != nil { return errors.Wrapf(err, "error reading %s", t.TemplatePath) } tmpl, err := template.New(t.Name).Funcs(sprig.TxtFuncMap()).Parse(string(b)) if err != nil { return errors.Wrapf(err, "error parsing %s", t.TemplatePath) } 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 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, Comment: t.Comment, Path: t.Path, Content: b, }, nil }