fix: cos credentials only for settings

Problem: the COS container and credentials should be exposed
in the executor settings.
Solution: add them there.

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

docs/further.md

@@ -100,6 +100,8 @@ $ snakemake --jobs 1 --executor googlebatch --googlebatch-bucket snakemake-cache
 The following environment variables are available within any Google batch run:
 
  - `BATCH_TASK_INDEX`: The index of the workflow step (Google Batch calls a "task")
+ - `GOOGLEBATCH_DOCKER_PASSWORD`: your docker registry passwork if using the container operating system (COS) and your container requires credentials
+ - `GOOGLEBATCH_DOCKER_USERNAME`: the same, but the username
 
 ### GPU
 
@@ -382,35 +384,6 @@ rule hello_world:
         "..."
 ```
 
-#### googlebatch_docker_username
-
-For use with the container operating system (COS) if your container needs credentials to access. Both this field and `googlebatch_docker_password` are required.
-
-```console
-rule hello_world:
-	output:
-		"...",
-	resources: 
-		googlebatch_docker_username="monkey"
-	shell:
-        "..."
-```
-
-
-
-#### googlebatch_docker_password
-
-For use with the container operating system (COS) if your container needs credentials to access. Both this field and `googlebatch_docker_username` are required.
-
-```console
-rule hello_world:
-	output:
-		"...",
-	resources: 
-		googlebatch_docker_password="monkey"
-	shell:
-        "..."
-```
 
 #### googlebatch_snippets
 

snakemake_executor_plugin_googlebatch/__init__.py

@@ -40,6 +40,33 @@ class ExecutorSettings(ExecutorSettingsBase):
         },
     )
 
+    container: Optional[str] = field(
+        default=None,
+        metadata={
+            "help": "A custom container for use with Google Batch COS",
+            "env_var": False,
+            "required": False,
+        },
+    )
+
+    docker_password: Optional[str] = field(
+        default=None,
+        metadata={
+            "help": "A docker registry password for COS if credentials are required",
+            "env_var": True,
+            "required": False,
+        },
+    )
+
+    docker_username: Optional[str] = field(
+        default=None,
+        metadata={
+            "help": "A docker registry username for COS if credentials are required",
+            "env_var": True,
+            "required": False,
+        },
+    )
+
     # mpitune configurations are validated on c2 and c2d instances only.
     machine_type: Optional[str] = field(
         default="c2-standard-4",