Support passing API Signing Key from the memory (#131)

* feat: Allow passing API key directly from memory

* docs: Improve key flag description

* docs: update

Author: durnik-ivo

.web-docs/components/builder/oci/README.md

@@ -101,7 +101,7 @@ based on which authentication method is used.
 - `use_instance_principals` (boolean) - Whether to use [Instance
   Principals](https://docs.cloud.oracle.com/en-us/iaas/Content/Identity/Tasks/callingservicesfrominstances.htm)
   instead of User Principals. If this key is set to true, setting any one of the `access_cfg_file`,
-  `access_cfg_file_account`, `region`, `tenancy_ocid`, `user_ocid`, `key_file`, `fingerprint`,
+  `access_cfg_file_account`, `region`, `tenancy_ocid`, `user_ocid`, `key`, `key_file`, `fingerprint`,
   `pass_phrase` parameters will cause an invalid configuration error.
   Defaults to `false`.
 
@@ -135,6 +135,11 @@ or configured for the default OCI CLI authenticaton profile.
   [OCI config file](https://docs.us-phoenix-1.oraclecloud.com/Content/API/Concepts/sdkconfig.htm)
   if present. This cannot be used along with the `use_instance_principals` key.
 
+- `key` (string) - The contents of the OCI API signing key. Overrides value provided by the `key_file`.
+  This cannot be used along with the `use_instance_principals` key. Also, the `key` is meant to be used with dynamic secret fetching,
+  for example, [`aws_secretsmanager` function](https://developer.hashicorp.com/packer/docs/templates/hcl_templates/functions/contextual/aws_secretsmanager),
+  storing secrets in a versioning system should be avoided.
+
 - `key_file` (string) - Full path and filename of the OCI API signing key. Overrides value provided
   by the [OCI config file](https://docs.us-phoenix-1.oraclecloud.com/Content/API/Concepts/sdkconfig.htm)
   if present. This cannot be used along with the `use_instance_principals` key.

builder/oci/config.go

@@ -91,6 +91,7 @@ type Config struct {
 	TenancyID    string `mapstructure:"tenancy_ocid"`
 	Region       string `mapstructure:"region"`
 	Fingerprint  string `mapstructure:"fingerprint"`
+	Key          string `mapstructure:"key"`
 	KeyFile      string `mapstructure:"key_file"`
 	PassPhrase   string `mapstructure:"pass_phrase"`
 	UsePrivateIP bool   `mapstructure:"use_private_ip"`
@@ -211,6 +212,9 @@ func (c *Config) Prepare(raws ...interface{}) error {
 		if c.Fingerprint != "" {
 			errs = packersdk.MultiErrorAppend(errs, errors.New("fingerprint"+message))
 		}
+		if c.Key != "" {
+			errs = packersdk.MultiErrorAppend(errs, errors.New("key"+message))
+		}
 		if c.KeyFile != "" {
 			errs = packersdk.MultiErrorAppend(errs, errors.New("key_file"+message))
 		}
@@ -246,6 +250,7 @@ func (c *Config) Prepare(raws ...interface{}) error {
 			c.AccessCfgFileAccount = "DEFAULT"
 		}
 
+		// Read API signing key
 		var keyContent []byte
 		if c.KeyFile != "" {
 			path, err := pathing.ExpandUser(c.KeyFile)
@@ -259,7 +264,11 @@ func (c *Config) Prepare(raws ...interface{}) error {
 				return err
 			}
 		}
+		if c.Key != "" {
+			keyContent = []byte(c.Key)
+		}
 
+		// Providers
 		fileProvider, _ := ocicommon.ConfigurationProviderFromFileWithProfile(c.AccessCfgFile, c.AccessCfgFileAccount, c.PassPhrase)
 		if c.Region == "" {
 			var region string

builder/oci/config.hcl2spec.go

@@ -398,6 +398,7 @@ func TestConfig(t *testing.T) {
 		"tenancy_ocid",
 		"region",
 		"fingerprint",
+		"key",
 		"key_file",
 		"pass_phrase",
 	}

builder/oci/config_test.go

@@ -108,7 +108,7 @@ based on which authentication method is used.
 - `use_instance_principals` (boolean) - Whether to use [Instance
   Principals](https://docs.cloud.oracle.com/en-us/iaas/Content/Identity/Tasks/callingservicesfrominstances.htm)
   instead of User Principals. If this key is set to true, setting any one of the `access_cfg_file`,
-  `access_cfg_file_account`, `region`, `tenancy_ocid`, `user_ocid`, `key_file`, `fingerprint`,
+  `access_cfg_file_account`, `region`, `tenancy_ocid`, `user_ocid`, `key`, `key_file`, `fingerprint`,
   `pass_phrase` parameters will cause an invalid configuration error.
   Defaults to `false`.
 
@@ -142,6 +142,11 @@ or configured for the default OCI CLI authenticaton profile.
   [OCI config file](https://docs.us-phoenix-1.oraclecloud.com/Content/API/Concepts/sdkconfig.htm)
   if present. This cannot be used along with the `use_instance_principals` key.
 
+- `key` (string) - The contents of the OCI API signing key. Overrides value provided by the `key_file`.
+  This cannot be used along with the `use_instance_principals` key. Also, the `key` is meant to be used with dynamic secret fetching,
+  for example, [`aws_secretsmanager` function](https://developer.hashicorp.com/packer/docs/templates/hcl_templates/functions/contextual/aws_secretsmanager),
+  storing secrets in a versioning system should be avoided.
+
 - `key_file` (string) - Full path and filename of the OCI API signing key. Overrides value provided
   by the [OCI config file](https://docs.us-phoenix-1.oraclecloud.com/Content/API/Concepts/sdkconfig.htm)
   if present. This cannot be used along with the `use_instance_principals` key.