120 lines
2.8 KiB
Go
120 lines
2.8 KiB
Go
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package template
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import (
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"io/ioutil"
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"github.com/hashicorp/terraform/config"
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"github.com/hashicorp/terraform/config/lang"
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"github.com/hashicorp/terraform/config/lang/ast"
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"github.com/hashicorp/terraform/helper/schema"
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)
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func resource() *schema.Resource {
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return &schema.Resource{
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Create: Create,
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Read: Read,
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Update: Update,
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Delete: Delete,
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Exists: Exists,
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Schema: map[string]*schema.Schema{
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"filename": &schema.Schema{
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Type: schema.TypeString,
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Required: true,
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Description: "file to read template from",
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},
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"vars": &schema.Schema{
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Type: schema.TypeMap,
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Optional: true,
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Default: make(map[string]interface{}),
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Description: "variables to substitute",
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},
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"rendered": &schema.Schema{
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Type: schema.TypeString,
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Computed: true,
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Default: nil,
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Description: "rendered template",
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},
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},
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}
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}
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func Create(d *schema.ResourceData, meta interface{}) error { return eval(d) }
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func Update(d *schema.ResourceData, meta interface{}) error { return eval(d) }
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func Read(d *schema.ResourceData, meta interface{}) error { return nil }
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func Delete(d *schema.ResourceData, meta interface{}) error {
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d.SetId("")
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return nil
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}
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func Exists(d *schema.ResourceData, meta interface{}) (bool, error) {
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// Reload every time in case something has changed.
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// This should be cheap, and cache invalidation is hard.
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return false, nil
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}
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func eval(d *schema.ResourceData) error {
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filename := d.Get("filename").(string)
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vars := d.Get("vars").(map[string]interface{})
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buf, err := ioutil.ReadFile(filename)
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if err != nil {
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return err
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}
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rendered, err := execute(string(buf), vars)
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if err != nil {
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return fmt.Errorf("failed to render %v: %v", filename, err)
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}
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d.Set("rendered", rendered)
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d.SetId(hash(rendered))
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return nil
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}
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// execute parses and executes a template using vars.
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func execute(s string, vars map[string]interface{}) (string, error) {
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root, err := lang.Parse(s)
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if err != nil {
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return "", err
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}
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varmap := make(map[string]ast.Variable)
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for k, v := range vars {
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// As far as I can tell, v is always a string.
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// If it's not, tell the user gracefully.
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s, ok := v.(string)
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if !ok {
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return "", fmt.Errorf("unexpected type for variable %q: %T", k, v)
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}
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varmap[k] = ast.Variable{
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Value: s,
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Type: ast.TypeString,
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}
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}
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cfg := lang.EvalConfig{
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GlobalScope: &ast.BasicScope{
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VarMap: varmap,
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FuncMap: config.Funcs,
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},
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}
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out, typ, err := lang.Eval(root, &cfg)
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if err != nil {
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return "", err
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}
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if typ != ast.TypeString {
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return "", fmt.Errorf("unexpected output ast.Type: %v", typ)
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}
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return out.(string), nil
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}
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func hash(s string) string {
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sha := sha256.Sum256([]byte(s))
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return hex.EncodeToString(sha[:])[:20]
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}
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