Add script for human readable output of metadata

misc_scripts/display_stratis_stack.py

@@ -0,0 +1,117 @@
+#!/usr/bin/env python3
+
+# Copyright 2024 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Use the thin pool metadata output to visualize the Stratis stack.
+"""
+
+# isort: STDLIB
+import argparse
+import json
+
+
+def print_cap_device(cap_device_metadata):
+    """
+    Print cap device info.
+    """
+    print(f"{cap_device_metadata['allocs'][0][1]}")
+
+
+def print_data_tier(data_tier_metadata):
+    """
+    Print data tier info.
+    """
+    devices = data_tier_metadata["blockdev"]["allocs"][0]
+
+    start_width = len(str(max(devices, key=lambda t: len(str(t["start"])))["start"]))
+    length_width = len(str(max(devices, key=lambda t: len(str(t["length"])))["length"]))
+
+    for items in devices:
+        print(
+            f" {items['parent']} {items['start']:>{start_width}} "
+            f"{items['length']:>{length_width}}"
+        )
+
+
+def print_flex_layer(flex_devs_metadata):
+    """
+    Print flex layer info.
+    """
+    flattened_items = [
+        (key, pair) for key, value in flex_devs_metadata.items() for pair in value
+    ]
+    sorted_items = list(sorted(flattened_items, key=lambda item: item[1][0]))
+
+    last_item = sorted_items[-1]
+    last_value = last_item[1]
+    last_total = int(last_value[0]) + int(last_value[1])
+    width = len(str(last_total))
+
+    for key, value in sorted_items:
+        print(
+            f"{value[0]:>{width}} {value[1]:>{width}} "
+            f"{int(value[0]) + int(value[1]):>{width}} {key}"
+        )
+
+    print()
+
+    totals = {}
+    for key, value in sorted_items:
+        totals[key] = (totals[key] + value[1]) if key in totals else value[1]
+
+    for key, value in totals.items():
+        print(f"{value:>{width}} {key}")
+
+    print()
+
+    print(f"Flex Total: {sum(v for v in totals.values())}")
+
+
+def _interpret_metadata(filename):
+    """
+    Interpret Stratis pool-level metadata.
+    """
+    with open(filename, "r", encoding="utf-8") as md_fd:
+        metadata = json.load(md_fd)
+
+    print("Data Tier:")
+    print_data_tier(metadata["backstore"]["data_tier"])
+    print()
+
+    print("Cap:")
+    print_cap_device(metadata["backstore"]["cap"])
+    print()
+
+    print("Flex:")
+    print_flex_layer(metadata["flex_devs"])
+
+
+def main():
+    """
+    Main method
+    """
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "metadata_file",
+        action="store",
+        help="file containing Stratis pool-level metadata",
+    )
+    args = parser.parse_args()
+    _interpret_metadata(args.metadata_file)
+
+
+if __name__ == "__main__":
+    main()