Scaffold terraform-provider-vault-secrets-arrstack

Configure the arrstack Vault secrets engine (backend config + roles) from
terraform-vault, matching the schema declared in terraform-vault #127.

- Add terraform-plugin-framework provider (local name arrstack) authenticating
  to Vault/OpenBao via address + token (VAULT_ADDR/VAULT_TOKEN fallback).
- Add arrstack_secret_backend resource: mounts the engine and writes <mount>/config.
- Add arrstack_secret_backend_role resource: manages <mount>/roles/<name>.
- Add Vault client, conversions, unit tests, Makefile, woodpecker CI + tag
  release to artifactapi terraform-unkin, examples, and README.

internal/provider/client.go

@@ -0,0 +1,130 @@
+package provider
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	vault "github.com/hashicorp/vault/api"
+)
+
+// vaultClient wraps the Vault/OpenBao API client with the operations this
+// provider needs to manage the arrstack secrets engine.
+type vaultClient struct {
+	api *vault.Client
+}
+
+func newVaultClient(address, token string) (*vaultClient, error) {
+	cfg := vault.DefaultConfig()
+	if cfg.Error != nil {
+		return nil, cfg.Error
+	}
+	if address != "" {
+		cfg.Address = address
+	}
+	c, err := vault.NewClient(cfg)
+	if err != nil {
+		return nil, err
+	}
+	if token != "" {
+		c.SetToken(token)
+	}
+	return &vaultClient{api: c}, nil
+}
+
+// mountConfig holds the tunable options applied when enabling the engine.
+type mountConfig struct {
+	DefaultLeaseTTL string
+	MaxLeaseTTL     string
+}
+
+// enableMount mounts the secrets engine of the given plugin type at path.
+func (c *vaultClient) enableMount(ctx context.Context, path, pluginType, description string, cfg mountConfig) error {
+	input := &vault.MountInput{
+		Type:        pluginType,
+		Description: description,
+		Config: vault.MountConfigInput{
+			DefaultLeaseTTL: cfg.DefaultLeaseTTL,
+			MaxLeaseTTL:     cfg.MaxLeaseTTL,
+		},
+	}
+	return c.api.Sys().MountWithContext(ctx, path, input)
+}
+
+// tuneMount updates tunable options of an existing mount (e.g. description).
+func (c *vaultClient) tuneMount(ctx context.Context, path, description string, cfg mountConfig) error {
+	input := vault.MountConfigInput{
+		Description:     &description,
+		DefaultLeaseTTL: cfg.DefaultLeaseTTL,
+		MaxLeaseTTL:     cfg.MaxLeaseTTL,
+	}
+	return c.api.Sys().TuneMountWithContext(ctx, path, input)
+}
+
+// mountInfo returns the mount at the given path, or nil if it does not exist.
+func (c *vaultClient) mountInfo(ctx context.Context, path string) (*vault.MountOutput, error) {
+	mounts, err := c.api.Sys().ListMountsWithContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	key := strings.TrimRight(path, "/") + "/"
+	if m, ok := mounts[key]; ok {
+		return m, nil
+	}
+	return nil, nil
+}
+
+// disableMount unmounts the secrets engine at path.
+func (c *vaultClient) disableMount(ctx context.Context, path string) error {
+	return c.api.Sys().UnmountWithContext(ctx, path)
+}
+
+// write writes data to an arbitrary path under the backend mount.
+func (c *vaultClient) write(ctx context.Context, path string, data map[string]interface{}) error {
+	_, err := c.api.Logical().WriteWithContext(ctx, path, data)
+	return err
+}
+
+// read reads an arbitrary path under the backend mount, returning nil if absent.
+func (c *vaultClient) read(ctx context.Context, path string) (map[string]interface{}, error) {
+	secret, err := c.api.Logical().ReadWithContext(ctx, path)
+	if err != nil {
+		return nil, err
+	}
+	if secret == nil {
+		return nil, nil
+	}
+	return secret.Data, nil
+}
+
+// delete removes an arbitrary path under the backend mount.
+func (c *vaultClient) delete(ctx context.Context, path string) error {
+	_, err := c.api.Logical().DeleteWithContext(ctx, path)
+	return err
+}
+
+func configPath(backend string) string {
+	return fmt.Sprintf("%s/config", strings.TrimRight(backend, "/"))
+}
+
+func rolePath(backend, name string) string {
+	return fmt.Sprintf("%s/roles/%s", strings.TrimRight(backend, "/"), name)
+}
+
+// isMountAlreadyExists reports whether the error is Vault's "path is already in
+// use" response, so callers can surface a friendlier message.
+func isMountAlreadyExists(err error) bool {
+	if err == nil {
+		return false
+	}
+	var respErr *vault.ResponseError
+	if errors.As(err, &respErr) {
+		for _, e := range respErr.Errors {
+			if strings.Contains(e, "path is already in use") {
+				return true
+			}
+		}
+	}
+	return false
+}