chore: use stringData for secrets
diff --git a/atmosphere/tasks/composite/openstack_helm.py b/atmosphere/tasks/composite/openstack_helm.py
index 444656d..6a09f89 100644
--- a/atmosphere/tasks/composite/openstack_helm.py
+++ b/atmosphere/tasks/composite/openstack_helm.py
@@ -1,7 +1,6 @@
 import mergedeep
 import pykube
 import yaml
-from oslo_serialization import base64
 
 from atmosphere.models import config
 from atmosphere.models.openstack_helm import values
@@ -21,7 +20,7 @@
         super().__init__(
             namespace=namespace,
             name=f"atmosphere-{chart}",
-            data={"values.yaml": base64.encode_as_text(values_yaml)},
+            data={"values.yaml": values_yaml},
         )
 
 
diff --git a/atmosphere/tasks/kubernetes/cert_manager.py b/atmosphere/tasks/kubernetes/cert_manager.py
index 40e9082..c40156e 100644
--- a/atmosphere/tasks/kubernetes/cert_manager.py
+++ b/atmosphere/tasks/kubernetes/cert_manager.py
@@ -1,5 +1,4 @@
 import pykube
-from oslo_serialization import base64
 
 from atmosphere.models import config
 from atmosphere.tasks import constants
@@ -118,9 +117,7 @@
                     constants.NAMESPACE_OPENSTACK,
                     "cert-manager-issuer-tsig-secret-key",
                     data={
-                        "tsig-secret-key": base64.encode_as_text(
-                            config.solver.tsig_secret
-                        ),
+                        "tsig-secret-key": config.solver.tsig_secret,
                     },
                 )
             )
@@ -148,9 +145,7 @@
                     constants.NAMESPACE_OPENSTACK,
                     "cert-manager-issuer-route53-credentials",
                     data={
-                        "secret-access-key": base64.encode_as_text(
-                            config.solver.secret_access_key
-                        ),
+                        "secret-access-key": config.solver.secret_access_key,
                     },
                 )
             )
@@ -178,8 +173,8 @@
                 constants.NAMESPACE_OPENSTACK,
                 "cert-manager-issuer-ca",
                 data={
-                    "tls.crt": base64.encode_as_text(config.certificate),
-                    "tls.key": base64.encode_as_text(config.private_key),
+                    "tls.crt": config.certificate,
+                    "tls.key": config.private_key,
                 },
             )
         )
diff --git a/atmosphere/tasks/kubernetes/v1.py b/atmosphere/tasks/kubernetes/v1.py
index fa205ae..4fbca09 100644
--- a/atmosphere/tasks/kubernetes/v1.py
+++ b/atmosphere/tasks/kubernetes/v1.py
@@ -70,6 +70,6 @@
                     "name": self._obj_name,
                     "namespace": self._obj_namespace,
                 },
-                "data": self._data,
+                "stringData": self._data,
             },
         )
diff --git a/atmosphere/tests/unit/tasks/kubernetes/test_cert_manager.py b/atmosphere/tests/unit/tasks/kubernetes/test_cert_manager.py
index c84aee5..81e6a2a 100644
--- a/atmosphere/tests/unit/tasks/kubernetes/test_cert_manager.py
+++ b/atmosphere/tests/unit/tasks/kubernetes/test_cert_manager.py
@@ -2,7 +2,6 @@
 
 import pykube
 import pytest
-from oslo_serialization import base64
 
 from atmosphere.models import config
 from atmosphere.tasks import constants
@@ -93,8 +92,8 @@
                         "name": "cert-manager-issuer-tsig-secret-key",
                         "namespace": constants.NAMESPACE_OPENSTACK,
                     },
-                    "data": {
-                        "tsig-secret-key": base64.encode_as_text("secret123"),
+                    "stringData": {
+                        "tsig-secret-key": "secret123",
                     },
                 },
                 {
@@ -164,10 +163,8 @@
                         "name": "cert-manager-issuer-route53-credentials",
                         "namespace": constants.NAMESPACE_OPENSTACK,
                     },
-                    "data": {
-                        "secret-access-key": base64.encode_as_text(
-                            "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
-                        ),
+                    "stringData": {
+                        "secret-access-key": "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY",
                     },
                 },
                 {
@@ -245,28 +242,24 @@
                         "name": "cert-manager-issuer-ca",
                         "namespace": constants.NAMESPACE_OPENSTACK,
                     },
-                    "data": {
-                        "tls.crt": base64.encode_as_text(
-                            textwrap.dedent(
-                                """\
-                                -----BEGIN CERTIFICATE-----
-                                MIIDBjCCAe4CCQDQ3Z0Z2Z0Z0jANBgkqhkiG9w0BAQsFADCBhTELMAkGA1UEBhMC
-                                VVMxEzARBgNVBAgTCkNhbGlmb3JuaWExFjAUBgNVBAcTDVNhbiBGcmFuY2lzY28x
-                                ...
-                                -----END CERTIFICATE-----
-                                """
-                            )
+                    "stringData": {
+                        "tls.crt": textwrap.dedent(
+                            """\
+                            -----BEGIN CERTIFICATE-----
+                            MIIDBjCCAe4CCQDQ3Z0Z2Z0Z0jANBgkqhkiG9w0BAQsFADCBhTELMAkGA1UEBhMC
+                            VVMxEzARBgNVBAgTCkNhbGlmb3JuaWExFjAUBgNVBAcTDVNhbiBGcmFuY2lzY28x
+                            ...
+                            -----END CERTIFICATE-----
+                            """
                         ),
-                        "tls.key": base64.encode_as_text(
-                            textwrap.dedent(
-                                """\
-                                -----BEGIN RSA PRIVATE KEY-----
-                                MIIEpAIBAAKCAQEAw3Z0Z2Z0Z0jANBgkqhkiG9w0BAQsFADCBhTELMAkGA1UEBhMC
-                                VVMxEzARBgNVBAgTCkNhbGlmb3JuaWExFjAUBgNVBAcTDVNhbiBGcmFuY2lzY28x
-                                ...
-                                -----END RSA PRIVATE KEY-----
-                                """
-                            )
+                        "tls.key": textwrap.dedent(
+                            """\
+                            -----BEGIN RSA PRIVATE KEY-----
+                            MIIEpAIBAAKCAQEAw3Z0Z2Z0Z0jANBgkqhkiG9w0BAQsFADCBhTELMAkGA1UEBhMC
+                            VVMxEzARBgNVBAgTCkNhbGlmb3JuaWExFjAUBgNVBAcTDVNhbiBGcmFuY2lzY28x
+                            ...
+                            -----END RSA PRIVATE KEY-----
+                            """
                         ),
                     },
                 },