1 files changed, 90 insertions, 0 deletions
diff --git a/services/settings/dumps/gen_last_modified.py b/services/settings/dumps/gen_last_modified.py
new file mode 100644
index 0000000000..d03f8fc096
--- /dev/null
+++ b/services/settings/dumps/gen_last_modified.py
@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import glob
+import json
+import os
+
+import buildconfig
+import mozpack.path as mozpath
+
+
+def get_last_modified(full_path_to_remote_settings_dump_file):
+    """
+    Get the last_modified for the given file name.
+    - File must exist
+    - Must be a JSON dictionary with a data list and a timestamp,
+      e.g. `{"data": [], "timestamp": 42}`
+    - Every element in `data` should contain a "last_modified" key.
+    - The first element must have the highest "last_modified" value.
+    """
+    with open(full_path_to_remote_settings_dump_file, "r", encoding="utf-8") as f:
+        changeset = json.load(f)
+
+    records = changeset["data"]
+    assert isinstance(records, list)
+    last_modified = changeset.get("timestamp")
+    assert isinstance(
+        last_modified, int
+    ), f"{full_path_to_remote_settings_dump_file} is missing the timestamp. See Bug 1725660"
+
+    return last_modified
+
+
+def main(output):
+    """
+    Generates a JSON file that maps "bucket/collection" to the last_modified
+    value within.
+
+    Returns a set of the file locations of the recorded RemoteSettings dumps,
+    so that the build backend can invoke this script again when needed.
+
+    The validity of the JSON file is verified through unit tests at
+    services/settings/test/unit/test_remote_settings_dump_lastmodified.js
+    """
+    # The following build targets currently use RemoteSettings dumps:
+    # Firefox               https://searchfox.org/mozilla-central/rev/94d6086481754e154b6f042820afab6bc9900a30/browser/installer/package-manifest.in#281-285        # NOQA: E501
+    # Firefox for Android   https://searchfox.org/mozilla-central/rev/94d6086481754e154b6f042820afab6bc9900a30/mobile/android/installer/package-manifest.in#88-91   # NOQA: E501
+    # Thunderbird           https://searchfox.org/comm-central/rev/89f957706bbda77e5f34e64e117e7ce121bb5d83/mail/installer/package-manifest.in#280-285              # NOQA: E501
+    # SeaMonkey             https://searchfox.org/comm-central/rev/89f957706bbda77e5f34e64e117e7ce121bb5d83/suite/installer/package-manifest.in#307-309             # NOQA: E501
+    assert buildconfig.substs["MOZ_BUILD_APP"] in (
+        "browser",
+        "mobile/android",
+        "comm/mail",
+        "comm/suite",
+    ), (
+        "Cannot determine location of Remote Settings "
+        f"dumps for platform {buildconfig.substs['MOZ_BUILD_APP']}"
+    )
+
+    dumps_locations = []
+    if buildconfig.substs["MOZ_BUILD_APP"] == "browser":
+        dumps_locations += ["services/settings/dumps/"]
+    elif buildconfig.substs["MOZ_BUILD_APP"] == "mobile/android":
+        dumps_locations += ["services/settings/dumps/"]
+    elif buildconfig.substs["MOZ_BUILD_APP"] == "comm/mail":
+        dumps_locations += ["services/settings/dumps/"]
+        dumps_locations += ["comm/mail/app/settings/dumps/"]
+    elif buildconfig.substs["MOZ_BUILD_APP"] == "comm/suite":
+        dumps_locations += ["services/settings/dumps/"]
+
+    remotesettings_dumps = {}
+    for dumps_location in dumps_locations:
+        dumps_root_dir = mozpath.join(buildconfig.topsrcdir, *dumps_location.split("/"))
+        for path in glob.iglob(mozpath.join(dumps_root_dir, "*", "*.json")):
+            folder, filename = os.path.split(path)
+            bucket = os.path.basename(folder)
+            collection, _ = os.path.splitext(filename)
+            remotesettings_dumps[f"{bucket}/{collection}"] = path
+
+    output_dict = {}
+    input_files = set()
+
+    for key, input_file in remotesettings_dumps.items():
+        input_files.add(input_file)
+        output_dict[key] = get_last_modified(input_file)
+
+    json.dump(output_dict, output, sort_keys=True)
+    return input_files