Add command function that returns an Either monad.

* gn3/commands.py: Import Either, Left, Right.
(monadic_run_cmd): New function.

Signed-off-by: Munyoki Kilyungi <me@bonfacemunyoki.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/gn3/commands.py b/gn3/commands.py
index b873d4d..79e1e7e 100644
--- a/gn3/commands.py
+++ b/gn3/commands.py
@@ -18,6 +18,8 @@ from uuid import uuid4
 from flask import current_app
 from redis.client import Redis  # Used only in type hinting
 
+from pymonad.either import Either, Left, Right
+
 from gn3.chancy import random_string
 from gn3.exceptions import RedisConnectionError
 
@@ -168,3 +170,24 @@ def run_async_cmd(
     cmd_id = queue_cmd(conn, job_queue, cmd, email, env)
     subprocess.Popen([f"{sys.executable}", "-m", "sheepdog.worker"]) # pylint: disable=[consider-using-with]
     return cmd_id
+
+
+def monadic_run_cmd(cmd) -> Either:
+    """Run a given command and return it's results as an Either monad"""
+    result = ""
+    try:
+        result = subprocess.run(cmd,
+                                capture_output=True,
+                                check=True).stdout.decode()
+    # This command does not exist
+    except FileNotFoundError as excpt:
+        return Left({
+            "command": cmd,
+            "error": str(excpt),
+        })
+    except subprocess.CalledProcessError as excpt:
+        return Left({
+            "command": cmd,
+            "error": str(excpt),
+        })
+    return Right(result)