load ssh identity lazily

on first use, to prevent a failure on startup if the file doesn't exist yet

(cherry picked from commit af48116)

Author: michalskrivanek

packages/jumpstarter-driver-ssh/jumpstarter_driver_ssh/driver.py

@@ -24,13 +24,6 @@ def __post_init__(self):
         if self.ssh_identity and self.ssh_identity_file:
             raise ConfigurationError("Cannot specify both ssh_identity and ssh_identity_file")
 
-        # If ssh_identity_file is provided, read it into ssh_identity
-        if self.ssh_identity_file:
-            try:
-                self.ssh_identity = Path(self.ssh_identity_file).read_text()
-            except Exception as e:
-                raise ConfigurationError(f"Failed to read ssh_identity_file '{self.ssh_identity_file}': {e}") from None
-
     @classmethod
     def client(cls) -> str:
         return "jumpstarter_driver_ssh.client.SSHWrapperClient"
@@ -48,4 +41,10 @@ def get_ssh_command(self):
     @export
     def get_ssh_identity(self):
         """Get the SSH identity key content"""
+        # If ssh_identity_file is provided, read it lazily and cache in ssh_identity
+        if self.ssh_identity is None and self.ssh_identity_file:
+            try:
+                self.ssh_identity = Path(self.ssh_identity_file).read_text()
+            except Exception as e:
+                raise ConfigurationError(f"Failed to read ssh_identity_file '{self.ssh_identity_file}': {e}") from None
         return self.ssh_identity

packages/jumpstarter-driver-ssh/jumpstarter_driver_ssh/driver_test.py

@@ -391,9 +391,17 @@ def test_ssh_identity_file_configuration():
         )
 
         # Test that the instance was created correctly
-        assert instance.ssh_identity == TEST_SSH_KEY
+        # ssh_identity should be None until first use (lazy loading)
+        assert instance.ssh_identity is None
         assert instance.ssh_identity_file == temp_file_path
 
+        # Test that get_ssh_identity() reads the file on first use
+        identity = instance.get_ssh_identity()
+        assert identity == TEST_SSH_KEY
+
+        # Test that ssh_identity is now cached
+        assert instance.ssh_identity == TEST_SSH_KEY
+
         # Test that the client class is correct
         assert instance.client() == "jumpstarter_driver_ssh.client.SSHWrapperClient"
     finally:
@@ -413,13 +421,17 @@ def test_ssh_identity_validation_error():
 
 
 def test_ssh_identity_file_read_error():
-    """Test SSH wrapper raises error when ssh_identity_file cannot be read"""
+    """Test SSH wrapper raises error when ssh_identity_file cannot be read on first use"""
+    # Instance creation should succeed (lazy loading)
+    instance = SSHWrapper(
+        children={"tcp": TcpNetwork(host="127.0.0.1", port=22)},
+        default_username="testuser",
+        ssh_identity_file="/nonexistent/path/to/key"
+    )
+
+    # Error should be raised when get_ssh_identity() is called
     with pytest.raises(ConfigurationError, match="Failed to read ssh_identity_file"):
-        SSHWrapper(
-            children={"tcp": TcpNetwork(host="127.0.0.1", port=22)},
-            default_username="testuser",
-            ssh_identity_file="/nonexistent/path/to/key"
-        )
+        instance.get_ssh_identity()
 
 
 def test_ssh_command_with_identity_string():