Make kms path generic to read from a file path instead of `KMS_AUTH_T…

…OKEN` (tektoncd#1167)

Previously when `signers.kms.auth.token-dir` was set, then the token was
read from the path specified in the field plus `KMS_AUTH_TOKEN` i.e.
(for e.g. /tmp/kms-secrets/KMS_AUTH_TOKEN) so user had to create the
secret with the key `KMS_AUTH_TOKEN`

Hence, with this patch now user can specify the path now and token will
be read from the path specified

Signed-off-by: PuneetPunamiya <ppunamiy@redhat.com>

docs/config.md

@@ -145,15 +145,16 @@ chains.tekton.dev/transparency-upload: "true"
 | :-------------------------------- | :------------------------------------------------------------------------------------------ | :--------------- | :------ |
 | `signers.kms.auth.address`        | URI of KMS server (e.g. the value of `VAULT_ADDR`)                                          |                  |
 | `signers.kms.auth.token`          | Auth token KMS server (e.g. the value of `VAULT_TOKEN`)                                     |                  |
-| `signers.kms.auth.token-dir`      | Path to store KMS server Auth token (e.g. `/etc/kms-secrets`)                               |                  |
+| `signers.kms.auth.token-path`     | Path to store KMS server Auth token (e.g. `/etc/kms-secrets`)                               |                  |
 | `signers.kms.auth.oidc.path`      | Path used for OIDC authentication (e.g. `jwt` for Vault)                                    |                  |
 | `signers.kms.auth.oidc.role`      | Role used for OIDC authentication                                                           |                  |
 | `signers.kms.auth.spire.sock`     | URI of the Spire socket used for KMS token (e.g. `unix:///tmp/spire-agent/public/api.sock`) |                  |
 | `signers.kms.auth.spire.audience` | Audience for requesting a SVID from Spire                                                   |                  |
+
 > NOTE:
 >
-> If `signers.kms.auth.token-dir` is set, create a secret with the key `KMS_AUTH_TOKEN` and ensure the Chains deployment mounts this secret to 
-> the path specified by `signers.kms.auth.token-dir`. 
+> If `signers.kms.auth.token-path` is set, create a secret and ensure the Chains deployment mounts this secret to
+> the path specified by `signers.kms.auth.token-path`.
 
 > [!IMPORTANT]
 > To project the latest token values without needing to recreate the pod, avoid using `subPath` in volume mount.

docs/signing.md

@@ -74,7 +74,7 @@ For Azure, this should have the structure of `azurekms://[VAULT_NAME][VAULT_URL]
 
 Most likely, you will need to set up some additional authentication so that the `chains-controller` deployment has access to your KMS service for signing.
 
-For Vault, if you use Token-based authentication, store the token as a secret with the key name `KMS_AUTH_TOKEN`. Mount this secret to a specific path within the tekton-chains-controller container. Specify the mounted path as the value for the `chains-config` config map key `signers.kms.auth.token-dir`. This approach can also be applied to other KMS providers that support token-based authentication. Note that the existing configuration option `signers.kms.auth.token` will still work. If both values are set, `signers.kms.auth.token-dir` will take precedence.
+For Vault, if you use Token-based authentication, store the token as a secret. Mount this secret to a specific path within the tekton-chains-controller container. Specify the mounted path as the value for the `chains-config` config map key `signers.kms.auth.token-path`. This approach can also be applied to other KMS providers that support token-based authentication. Note that the existing configuration option `signers.kms.auth.token` will still work. If both values are set, `signers.kms.auth.token-path` will take precedence.
 
 For GCP/GKE, we suggest enabling [Workload Identity](https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity), and giving your service account `Cloud KMS Admin` permissions.
 Other Service Account techniques would work as well.

pkg/chains/signing/kms/kms.go

@@ -21,7 +21,6 @@ import (
 	"net"
 	"net/url"
 	"os"
-	"path/filepath"
 	"strings"
 	"time"
 
@@ -108,8 +107,8 @@ func NewSigner(ctx context.Context, cfg config.KMSSigner) (*Signer, error) {
 	// as direct value set from signers.kms.auth.token.
 	// If both values are set, priority will be given to token-dir.
 
-	if cfg.Auth.TokenDir != "" {
-		rpcAuthToken, err := getKMSAuthToken(cfg.Auth.TokenDir)
+	if cfg.Auth.TokenPath != "" {
+		rpcAuthToken, err := getKMSAuthToken(cfg.Auth.TokenPath)
 		if err != nil {
 			return nil, err
 		}
@@ -138,15 +137,10 @@ func NewSigner(ctx context.Context, cfg config.KMSSigner) (*Signer, error) {
 }
 
 // getKMSAuthToken retreives token from the given mount path
-func getKMSAuthToken(dir string) (string, error) {
-	tokenEnv := "KMS_AUTH_TOKEN" // #nosec G101
-
-	// Cocatenate secret mount path specified in signers.kms.auth.token-dir and
-	// secret key name KMS_AUTH_TOKEN
-	filePath := filepath.Join(dir, tokenEnv)
-	fileData, err := os.ReadFile(filePath)
+func getKMSAuthToken(path string) (string, error) {
+	fileData, err := os.ReadFile(path)
 	if err != nil {
-		return "", fmt.Errorf("reading file %q in directory %q: %w", tokenEnv, dir, err)
+		return "", fmt.Errorf("reading file in %q: %w", path, err)
 	}
 
 	// A trailing newline is fairly common in mounted files, so remove it.

pkg/chains/signing/kms/kms_test.go

@@ -21,7 +21,6 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
-	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -137,7 +136,7 @@ func TestGetKMSAuthToken_NotADirectory(t *testing.T) {
 	defer os.Remove(tempFile.Name())
 
 	token, err := getKMSAuthToken(tempFile.Name())
-	assert.Error(t, err)
+	assert.Equal(t, err, nil)
 	assert.Equal(t, "", token)
 }
 
@@ -151,13 +150,14 @@ func TestGetKMSAuthToken_FileNotFound(t *testing.T) {
 
 // Test for verifying return value of getKMSAuthToken
 func TestGetKMSAuthToken_ValidToken(t *testing.T) {
-	tempDir := t.TempDir() // Creates a temporary directory
-	tokenPath := filepath.Join(tempDir, "KMS_AUTH_TOKEN")
+	tempFile, err := os.CreateTemp("", "vault-token")
+	assert.NoError(t, err)
+	defer os.Remove(tempFile.Name())
 
-	err := os.WriteFile(tokenPath, []byte("test-token"), 0644) // write a sample token "test-token"
+	err = os.WriteFile(tempFile.Name(), []byte("test-token"), 0644) // write a sample token "test-token"
 	assert.NoError(t, err)
 
-	token, err := getKMSAuthToken(tempDir)
+	token, err := getKMSAuthToken(tempFile.Name())
 	assert.NoError(t, err)
 	assert.Equal(t, "test-token", token) // verify the value returned by getKMSAuthToken matches "test-token"
 }

pkg/config/config.go

@@ -91,11 +91,11 @@ type KMSSigner struct {
 
 // KMSAuth configures authentication to the KMS server
 type KMSAuth struct {
-	Address  string
-	Token    string
-	TokenDir string
-	OIDC     KMSAuthOIDC
-	Spire    KMSAuthSpire
+	Address   string
+	Token     string
+	TokenPath string
+	OIDC      KMSAuthOIDC
+	Spire     KMSAuthSpire
 }
 
 // KMSAuthOIDC configures settings to authenticate with OIDC
@@ -193,7 +193,7 @@ const (
 	kmsAuthAddress       = "signers.kms.auth.address"
 	kmsAuthToken         = "signers.kms.auth.token"
 	kmsAuthOIDCPath      = "signers.kms.auth.oidc.path"
-	kmsAuthTokenDir      = "signers.kms.auth.token-dir" // #nosec G101
+	kmsAuthTokenPath     = "signers.kms.auth.token-path" // #nosec G101
 	kmsAuthOIDCRole      = "signers.kms.auth.oidc.role"
 	kmsAuthSpireSock     = "signers.kms.auth.spire.sock"
 	kmsAuthSpireAudience = "signers.kms.auth.spire.audience"
@@ -313,7 +313,7 @@ func NewConfigFromMap(data map[string]string) (*Config, error) {
 		asString(kmsSignerKMSRef, &cfg.Signers.KMS.KMSRef),
 		asString(kmsAuthAddress, &cfg.Signers.KMS.Auth.Address),
 		asString(kmsAuthToken, &cfg.Signers.KMS.Auth.Token),
-		asString(kmsAuthTokenDir, &cfg.Signers.KMS.Auth.TokenDir),
+		asString(kmsAuthTokenPath, &cfg.Signers.KMS.Auth.TokenPath),
 		asString(kmsAuthOIDCPath, &cfg.Signers.KMS.Auth.OIDC.Path),
 		asString(kmsAuthOIDCRole, &cfg.Signers.KMS.Auth.OIDC.Role),
 		asString(kmsAuthSpireSock, &cfg.Signers.KMS.Auth.Spire.Sock),