Fixes #35: Adding support for loading configs from stdin

src/arcaflow_plugin_sdk/plugin.py

@@ -499,7 +499,7 @@ def run(
             "-f",
             "--file",
             dest="filename",
-            help="Configuration file to read configuration from.",
+            help="Configuration file to read configuration from. Pass - to read from stdin.",
             metavar="FILE",
         )
         parser.add_option(
@@ -535,7 +535,7 @@ def run(
         else:
             step_id = list(s.steps.keys())[0]
         if options.filename is not None:
-            return _execute_file(step_id, s, options, stdout, stderr)
+            return _execute_file(step_id, s, options, stdin, stdout, stderr)
         elif options.json_schema is not None:
             return _print_json_schema(step_id, s, options, stdout)
         else:
@@ -567,9 +567,19 @@ def build_schema(*args: schema.StepSchema) -> schema.Schema:
     )
 
 
-def _execute_file(step_id, s, options, stdout, stderr) -> int:
+def _execute_file(
+        step_id: str,
+        s: schema.StepSchema,
+        options,
+        stdin: io.TextIOWrapper,
+        stdout: io.TextIOWrapper,
+        stderr: io.TextIOWrapper
+) -> int:
     filename: str = options.filename
-    data = serialization.load_from_file(filename)
+    if filename == "-":
+        data = serialization.load_from_stdin(stdin)
+    else:
+        data = serialization.load_from_file(filename)
     original_stdout = sys.stdout
     original_stderr = sys.stderr
     if options.debug:

src/arcaflow_plugin_sdk/serialization.py

@@ -1,3 +1,4 @@
+import io
 import json
 from typing import Any
 
@@ -26,6 +27,32 @@ def load_from_file(file_name: str) -> Any:
         raise LoadFromFileException("Unsupported file extension: {}".format(file_name))
 
 
+def load_from_stdin(stdin: io.TextIOWrapper) -> Any:
+    """
+    This function reads from the standard input and returns a Python data structure.
+    :param stdin: the standard input
+    :return: the decoded structure.
+    """
+    stdin_data = stdin.read()
+    if stdin_data.startswith("{"):
+        try:
+            return json.loads(stdin_data)
+        except BaseException as e:
+            raise LoadFromStdinException("Failed to load JSON from stdin: {}".format(e.__str__())) from e
+    else:
+        try:
+            return yaml.safe_load(stdin_data)
+        except BaseException as e:
+            raise LoadFromStdinException("Failed to load YAML from stdin: {}".format(e.__str__())) from e
+
+
+class LoadFromStdinException(Exception):
+    msg: str
+
+    def __str__(self) -> str:
+        return self.msg
+
+
 class LoadFromFileException(Exception):
     msg: str