Support storing and retrieving a local token.

Closes pulp#926

pulpcore/cli/common/generic.py

@@ -5,6 +5,7 @@
 import typing as t
 from contextlib import closing
 from functools import lru_cache, wraps
+from pathlib import Path
 
 import click
 import requests
@@ -245,8 +246,38 @@ def __init__(self, *args, **kwargs):
                 self.flow = kwargs.get("flow")
                 self.token_url = self.flow["flows"]["clientCredentials"]["tokenUrl"]
                 self.scope = [*self.flow["flows"]["clientCredentials"]["scopes"]][0]
+                self.token = ""
 
             def __call__(self, request):
+                self.retrieve_local_token()
+                if self.is_token_expired():
+                    self.retrieve_token()
+
+                request.headers["Authorization"] = f"Bearer {self.token['access_token']}"
+                return request
+
+            def is_token_expired(self):
+                if self.token:
+                    issued_at = datetime.datetime.fromisoformat(self.token["issued_at"])
+                    expires_in = datetime.timedelta(seconds=self.token["expires_in"])
+                    timedelta = issued_at + expires_in - datetime.timedelta(seconds=5)
+                    if timedelta >= datetime.datetime.now():
+                        return False
+                return True
+
+            def store_local_token(self):
+                TOKEN_LOCATION = (Path(click.utils.get_app_dir("pulp"), "token.json"))
+                with Path(TOKEN_LOCATION).open("w") as token_file:
+                    token = json.dumps(self.token)
+                    token_file.write(token)
+
+            def retrieve_local_token(self):
+                TOKEN_LOCATION = (Path(click.utils.get_app_dir("pulp"), "token.json"))
+                with Path(TOKEN_LOCATION).open("r") as token_file:
+                    token_json = token_file.read()
+                    self.token = json.loads(token_json)
+
+            def retrieve_token(self):
                 data = {
                     "client_id": self.client_id,
                     "client_secret": self.client_secret,
@@ -256,10 +287,9 @@ def __call__(self, request):
 
                 response: requests.Response = requests.post(self.token_url, data=data)
 
-                token = response.json() if response.status_code == 200 else None
-
-                request.headers["Authorization"] = f"Bearer {token['access_token']}"
-                return request
+                self.token = response.json() if response.status_code == 200 else None
+                self.token["issued_at"] = datetime.datetime.now().isoformat()
+                self.store_local_token()
 
         return OAuth2AuthBase(
             username=self.pulp_ctx.username, password=self.pulp_ctx.password, flow=flow