Feature/flow management cli (#346)

Flow management API + various flow management commands

trustgraph-cli/scripts/tg-delete-flow-class
trustgraph-cli/scripts/tg-get-flow-class
trustgraph-cli/scripts/tg-put-flow-class
trustgraph-cli/scripts/tg-show-flow-classes
trustgraph-cli/scripts/tg-show-flows
trustgraph-cli/scripts/tg-start-flow
trustgraph-cli/scripts/tg-stop-flow

trustgraph-cli/scripts/tg-show-flow-classes

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+
+"""
+"""
+
+import argparse
+import os
+import tabulate
+from trustgraph.api import Api
+import json
+
+default_url = os.getenv("TRUSTGRAPH_URL", 'http://localhost:8088/')
+
+def show_flow_classes(url):
+
+    api = Api(url)
+
+    class_names = api.flow_list_classes()
+
+    classes = []
+
+    for class_name in class_names:
+        cls = api.flow_get_class(class_name)
+        classes.append((
+            class_name,
+            cls.get("description", ""),
+            ", ".join(cls.get("tags", [])),
+        ))
+
+    print(tabulate.tabulate(
+        classes,
+        tablefmt="pretty",
+        maxcolwidths=[None, 40, 20],
+        stralign="left",
+        headers = ["flow class", "description", "tags"],
+    ))
+
+def main():
+
+    parser = argparse.ArgumentParser(
+        prog='tg-show-flow-classes',
+        description=__doc__,
+    )
+
+    parser.add_argument(
+        '-u', '--api-url',
+        default=default_url,
+        help=f'API URL (default: {default_url})',
+    )
+
+    args = parser.parse_args()
+
+    try:
+
+        show_flow_classes(
+            url=args.api_url,
+        )
+
+    except Exception as e:
+
+        print("Exception:", e, flush=True)
+
+main()
+