fix: Use URL-safe base64 encoding for X-Registry-Auth

CHANGES/941.bugfix

@@ -0,0 +1 @@
+Fix issue authenticating against private registries where the `X-Registry-Auth` header would require URL-safe substitutions.

CONTRIBUTORS.txt

@@ -24,6 +24,7 @@ Konstantin Valetov
 Martin Koppehel
 Nikolay Novik
 Paul Tagliamonte
+Robin Tweedie
 Sanghun Lee
 Tianon Gravi
 Tommy Beadle

aiodocker/utils.py

@@ -298,4 +298,4 @@ def compose_auth_header(
         auth_json = json.dumps(config).encode("utf-8")
     else:
         raise TypeError("auth must be base64 encoded string/bytes or a dictionary")
-    return base64.b64encode(auth_json).decode("ascii")
+    return base64.urlsafe_b64encode(auth_json).decode("ascii")

tests/test_utils.py

@@ -68,3 +68,11 @@ def test_clean_filters() -> None:
 
     with pytest.raises(TypeError):
         assert utils.clean_filters(filters=())
+
+
+def test_compose_auth_header():
+    auth = {"username": "alice", "password": "~"}
+    assert (
+        utils.compose_auth_header(auth)
+        == "eyJ1c2VybmFtZSI6ICJhbGljZSIsICJwYXNzd29yZCI6ICJ-In0="
+    )