140 lines
3.1 KiB
Go
140 lines
3.1 KiB
Go
package packer
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import (
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"bytes"
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"fmt"
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"os"
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"strconv"
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"strings"
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"text/template"
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"time"
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"github.com/mitchellh/packer/common/uuid"
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)
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// InitTime is the UTC time when this package was initialized. It is
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// used as the timestamp for all configuration templates so that they
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// match for a single build.
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var InitTime time.Time
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func init() {
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InitTime = time.Now().UTC()
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}
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// ConfigTemplate processes string data as a text/template with some common
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// elements and functions available. Plugin creators should process as
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// many fields as possible through this.
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type ConfigTemplate struct {
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UserVars map[string]string
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root *template.Template
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i int
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}
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// NewConfigTemplate creates a new configuration template processor.
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func NewConfigTemplate() (*ConfigTemplate, error) {
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result := &ConfigTemplate{
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UserVars: make(map[string]string),
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}
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result.root = template.New("configTemplateRoot")
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result.root.Funcs(template.FuncMap{
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"env": templateDisableEnv,
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"pwd": templatePwd,
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"isotime": templateISOTime,
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"timestamp": templateTimestamp,
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"user": result.templateUser,
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"uuid": templateUuid,
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"upper": strings.ToUpper,
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"lower": strings.ToLower,
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})
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return result, nil
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}
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// Process processes a single string, compiling and executing the template.
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func (t *ConfigTemplate) Process(s string, data interface{}) (string, error) {
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tpl, err := t.root.New(t.nextTemplateName()).Parse(s)
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if err != nil {
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return "", err
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}
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buf := new(bytes.Buffer)
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if err := tpl.Execute(buf, data); err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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// Validate the template.
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func (t *ConfigTemplate) Validate(s string) error {
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root, err := t.root.Clone()
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if err != nil {
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return err
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}
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_, err = root.New("template").Parse(s)
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return err
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}
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// Add additional functions to the template
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func (t *ConfigTemplate) Funcs(funcs template.FuncMap) {
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t.root.Funcs(funcs)
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}
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func (t *ConfigTemplate) nextTemplateName() string {
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name := fmt.Sprintf("tpl%d", t.i)
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t.i++
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return name
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}
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// User is the function exposed as "user" within the templates and
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// looks up user variables.
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func (t *ConfigTemplate) templateUser(n string) (string, error) {
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result, ok := t.UserVars[n]
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if !ok {
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return "", fmt.Errorf("unknown user var: %s", n)
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}
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return result, nil
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}
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func templateDisableEnv(n string) (string, error) {
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return "", fmt.Errorf(
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"Environmental variables can only be used as default values for user variables.")
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}
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func templateDisableUser(n string) (string, error) {
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return "", fmt.Errorf(
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"User variable can't be used within a default value for a user variable: %s", n)
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}
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func templateEnv(n string) string {
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return os.Getenv(n)
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}
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func templateISOTime(timeFormat ...string) (string, error) {
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if len(timeFormat) == 0 {
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return time.Now().UTC().Format(time.RFC3339), nil
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}
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if len(timeFormat) > 1 {
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return "", fmt.Errorf("too many values, 1 needed: %v", timeFormat)
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}
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return time.Now().UTC().Format(timeFormat[0]), nil
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}
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func templatePwd() (string, error) {
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return os.Getwd()
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}
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func templateTimestamp() string {
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return strconv.FormatInt(InitTime.Unix(), 10)
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}
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func templateUuid() string {
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return uuid.TimeOrderedUUID()
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}
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