Fix SSHKeyPairDefinition

The base `ResourceDefinition` class requires the `config` property's
type annotation to not be a string (added cd9319b / a70af27),
but the `ssh_keypair.py` module activates postponed annotations via the
`from __future__ import annotations` syntax (added e48422a), which
turns all type annotations in the module into strings[1], breaking the
`SSHKeyPairDefinition` class when initialized.

Thus any defined `resources.sshKeyPairs` break `nixops` commands,
causing failures with the message:

```
TypeError: <class 'nixops.resources.ssh_keypair.SSHKeyPairDefinition'>.config's type annotation is not allowed to be a string, see: https://nixops.readthedocs.io/en/latest/plugins/authoring.html
```

A number of possible workarounds for this, but the simplest would seem
to just not activate PEP 563-style postponed annotations in
`ssh_keypair.py`.

[1] https://peps.python.org/pep-0563/

nixops/resources/__init__.py

@@ -63,7 +63,7 @@ def __init__(self, name: str, config: ResourceEval):
                 )
             else:
                 raise TypeError(
-                    f"{self.__class__}.config's type annotation is not allowed to be a string, see: https://nixops.readthedocs.io/en/latest/plugins/authoring.html"
+                    f"{self.__class__}.config's type annotation is not allowed to be a string (or defined in a module using PEP 563 postponed annotations), see: https://nixops.readthedocs.io/en/latest/plugins/authoring.html"
                 )
 
         if not issubclass(config_type, ResourceOptions):

nixops/resources/ssh_keypair.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 # Automatic provisioning of SSH key pairs.
 from typing import Type, Dict, Optional
 
@@ -14,11 +12,11 @@ class SSHKeyPairDefinition(nixops.resources.ResourceDefinition):
     config: nixops.resources.ResourceOptions
 
     @classmethod
-    def get_type(cls: Type[SSHKeyPairDefinition]) -> str:
+    def get_type(cls: Type["SSHKeyPairDefinition"]) -> str:
         return "ssh-keypair"
 
     @classmethod
-    def get_resource_type(cls: Type[SSHKeyPairDefinition]) -> str:
+    def get_resource_type(cls: Type["SSHKeyPairDefinition"]) -> str:
         return "sshKeyPairs"
 
     def __init__(self, name: str, config: nixops.resources.ResourceEval):
@@ -38,7 +36,7 @@ class SSHKeyPairState(nixops.resources.ResourceState[SSHKeyPairDefinition]):
     private_key: Optional[str] = nixops.util.attr_property("privateKey", None)
 
     @classmethod
-    def get_type(cls: Type[SSHKeyPairState]) -> str:
+    def get_type(cls: Type["SSHKeyPairState"]) -> str:
         return "ssh-keypair"
 
     def __init__(self, depl: "nixops.deployment.Deployment", name: str, id: RecordId):

tests/functional/ssh-key-pair-resource.nix

@@ -0,0 +1,5 @@
+{
+  network = {};
+
+  resources.sshKeyPairs.ssh-key = {};
+}

tests/functional/test_ssh_key_pair_resource.py

@@ -0,0 +1,20 @@
+from os import path
+
+from tests.functional.generic_deployment_test import GenericDeploymentTest
+
+from nixops.evaluation import NetworkFile
+
+parent_dir = path.dirname(__file__)
+
+ssh_key_pair_spec = "%s/ssh-key-pair-resource.nix" % (parent_dir)
+
+
+class TestSSHKeyPairResource(GenericDeploymentTest):
+    def setup(self):
+        super(TestSSHKeyPairResource, self).setup()
+        self.depl.network_expr = NetworkFile(ssh_key_pair_spec)
+
+    def test_evaluate(self):
+        self.depl.evaluate()
+
+        assert "ssh-key" in self.depl.definitions