Add cron service and cleanup script

src/pebble.py

@@ -52,7 +52,10 @@ def restart_synapse(self, container: ops.model.Container) -> None:
             container: Synapse container.
         """
         logger.debug("Restarting the Synapse container")
-        container.add_layer(synapse.SYNAPSE_CONTAINER_NAME, self._pebble_layer, combine=True)
+        container.add_layer(synapse.SYNAPSE_SERVICE_NAME, self._pebble_layer, combine=True)
+        container.add_layer(
+            synapse.SYNAPSE_CRON_SERVICE_NAME, self._cron_pebble_layer, combine=True
+        )
         container.restart(synapse.SYNAPSE_SERVICE_NAME)
 
     def replan_nginx(self, container: ops.model.Container) -> None:
@@ -252,3 +255,25 @@ def _mjolnir_pebble_layer(self) -> ops.pebble.LayerDict:
             },
         }
         return typing.cast(ops.pebble.LayerDict, layer)
+
+    @property
+    def _cron_pebble_layer(self) -> ops.pebble.LayerDict:
+        """Generate pebble config for the cron service.
+
+        Returns:
+            The pebble configuration for the cron service.
+        """
+        layer = {
+            "summary": "Synapse ncron layer",
+            "description": "Synapse cron layer",
+            "services": {
+                synapse.SYNAPSE_CRON_SERVICE_NAME: {
+                    "override": "replace",
+                    "summary": "Cron service",
+                    "command": "/usr/local/bin/run_cron.py",
+                    "environment": synapse.get_environment(self._charm_state),
+                    "startup": "enabled",
+                },
+            },
+        }
+        return typing.cast(ops.pebble.LayerDict, layer)

src/synapse/__init__.py

@@ -43,6 +43,7 @@
     SYNAPSE_CONFIG_DIR,
     SYNAPSE_CONFIG_PATH,
     SYNAPSE_CONTAINER_NAME,
+    SYNAPSE_CRON_SERVICE_NAME,
     SYNAPSE_DATA_DIR,
     SYNAPSE_NGINX_CONTAINER_NAME,
     SYNAPSE_NGINX_PORT,

src/synapse/workload.py

@@ -30,6 +30,7 @@
 SYNAPSE_COMMAND_PATH = "/start.py"
 SYNAPSE_CONFIG_PATH = f"{SYNAPSE_CONFIG_DIR}/homeserver.yaml"
 SYNAPSE_CONTAINER_NAME = "synapse"
+SYNAPSE_CRON_SERVICE_NAME = "synapse-cron"
 SYNAPSE_DATA_DIR = "/data"
 SYNAPSE_NGINX_CONTAINER_NAME = "synapse-nginx"
 SYNAPSE_NGINX_PORT = 8080

synapse_rock/cron/cron.weekly/remote_content_empty_directory_cleanup.py

@@ -0,0 +1,38 @@
+#!/usr/bin/python3
+
+"""
+Synapse does not purge empty directories from its media content storage locations.
+Those can accumulate and eat up inodes and space.
+Related: https://github.com/matrix-org/synapse/issues/16229
+Related: https://github.com/matrix-org/synapse/issues/7690
+"""
+
+import os
+import json
+
+# We assume that pyyaml is present thanks to synapse
+import yaml
+
+# This function is meant to fail if the media_store_path can't be found
+def load_media_store_path(file_path: str) -> str:
+    with open(file_path, 'r', encoding='utf-8') as file:
+        data = yaml.safe_load(file)
+        return data['media_store_path']
+
+def delete_empty_dirs(path: str) -> None:
+    for root, dirs, _ in os.walk(path, topdown=False):
+        for dir in dirs:
+            try:
+                os.rmdir(os.path.join(root, dir))
+            except OSError:
+                continue
+
+if __name__ == '__main__':
+    # load the environment from the file produced by /usr/local/bin/run_cron.py
+    if os.path.isfile("/var/local/cron/environment.json"):
+        with open("/var/local/cron/environment.json", "r") as env_fd:
+            env = json.load(env_fd)
+        if os.path.isfile(env["SYNAPSE_CONFIG_PATH"]):
+            path = load_media_store_path(env["SYNAPSE_CONFIG_PATH"])
+            if path:
+                delete_empty_dirs(path)

synapse_rock/rockcraft.yaml

@@ -13,77 +13,97 @@ license: Apache-2.0
 platforms:
   amd64:
 parts:
-    synapse:
-        build-packages:
-            - build-essential
-            - curl
-            - git
-            - libffi-dev
-            - libicu-dev
-            - libjpeg-dev
-            - libpq-dev
-            - libssl-dev
-            - libwebp-dev
-            - libxml++2.6-dev
-            - libxslt1-dev
-            - openssl
-            - pkg-config
-            - python3-dev
-            - python3-pip
-            - python3-setuptools
-            - zlib1g-dev
-        stage-packages:
-            - bash
-            - coreutils
-            - curl
-            - gosu
-            - libffi-dev
-            - libicu70
-            - libjemalloc2
-            - libjpeg-turbo8
-            - libpq5
-            - libssl-dev
-            - libwebp7
-            - openssl
-            - python3
-            - xmlsec1
-        stage-snaps:
-            - mjolnir/latest/edge
-            - matrix-appservice-irc/latest/edge
-        plugin: nil
-        source: https://github.com/matrix-org/synapse/
-        source-type: git
-        source-tag: v1.96.1
-        override-build: |
-            craftctl default
-            export RUSTUP_HOME=/rust
-            export CARGO_HOME=/cargo
-            export PATH=/cargo/bin:/rust/bin:$PATH
-            export CARGO_NET_GIT_FETCH_WITH_CLI=false
-            mkdir -p /rust /cargo /synapse /install
-            curl -m 30 -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --default-toolchain stable --profile minimal
-            /rust/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc -V > $CRAFT_PART_INSTALL/rust-version
-            pip3 install -U pip setuptools
-            pip3 install --root-user-action=ignore "poetry==1.3.2"
-            cp pyproject.toml poetry.lock /synapse/
-            /usr/local/bin/poetry export --extras all -o /synapse/requirements.txt
-            pip3 install --prefix="/install" --no-deps --no-warn-script-location -r /synapse/requirements.txt
-            cp -r synapse /synapse/
-            cp -r rust /synapse/
-            cp pyproject.toml README.rst build_rust.py Cargo.toml Cargo.lock /synapse/
-            pip3 install --prefix="/install" --no-deps --no-warn-script-location /synapse[all];
-            cp docker/start.py $CRAFT_PART_INSTALL/
-            chmod 755 $CRAFT_PART_INSTALL/start.py
-            sed -i 's/#!\/usr\/local\/bin\/python/#!\/usr\/bin\/python3/' $CRAFT_PART_INSTALL/start.py
-            cp -r docker/conf $CRAFT_PART_INSTALL/
-            cp -r /usr/local $CRAFT_PART_INSTALL/usr/
-            cp -r /install/local/* $CRAFT_PART_INSTALL/usr/local/
-            mkdir -p $CRAFT_PART_INSTALL/usr/local/attributemaps
-            chmod 755 $CRAFT_PART_INSTALL/usr/local/attributemaps
-        overlay-packages:
-            - ca-certificates
-    synapse-conf:
-        plugin: dump
-        source: attributemaps
-        organize:
-            login_ubuntu.py: /usr/local/attributemaps/login_ubuntu.py
+  scripts:
+    plugin: dump
+    source: scripts
+    organize:
+      "*": usr/local/bin/
+  cron:
+    after:
+      - scripts
+    stage-packages:
+      - cron
+    plugin: dump
+    source: cron
+    organize:
+      "cron.hourly/*": /etc/cron.hourly
+      "cron.daily/*": /etc/cron.daily
+      "cron.weekly/*": /etc/cron.weekly
+      "cron.monthly/*": /etc/cron.monthly
+    override-prime: |
+      craftctl default
+      chmod -R +x /etc/cron.*
+  synapse:
+    build-packages:
+    - build-essential
+    - curl
+    - git
+    - libffi-dev
+    - libicu-dev
+    - libjpeg-dev
+    - libpq-dev
+    - libssl-dev
+    - libwebp-dev
+    - libxml++2.6-dev
+    - libxslt1-dev
+    - openssl
+    - pkg-config
+    - python3-dev
+    - python3-pip
+    - python3-setuptools
+    - zlib1g-dev
+    stage-packages:
+      - bash
+      - coreutils
+      - curl
+      - gosu
+      - libffi-dev
+      - libicu70
+      - libjemalloc2
+      - libjpeg-turbo8
+      - libpq5
+      - libssl-dev
+      - libwebp7
+      - openssl
+      - python3
+      - xmlsec1
+    stage-snaps:
+      - mjolnir/latest/edge
+      - matrix-appservice-irc/latest/edge
+    plugin: nil
+    source: https://github.com/matrix-org/synapse/
+    source-type: git
+    source-tag: v1.96.1
+    override-build: |
+      craftctl default
+      export RUSTUP_HOME=/rust
+      export CARGO_HOME=/cargo
+      export PATH=/cargo/bin:/rust/bin:$PATH
+      export CARGO_NET_GIT_FETCH_WITH_CLI=false
+      mkdir -p /rust /cargo /synapse /install
+      curl -m 30 -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --default-toolchain stable --profile minimal
+      /rust/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc -V > $CRAFT_PART_INSTALL/rust-version
+      pip3 install -U pip setuptools
+      pip3 install --root-user-action=ignore "poetry==1.3.2"
+      cp pyproject.toml poetry.lock /synapse/
+      /usr/local/bin/poetry export --extras all -o /synapse/requirements.txt
+      pip3 install --prefix="/install" --no-deps --no-warn-script-location -r /synapse/requirements.txt
+      cp -r synapse /synapse/
+      cp -r rust /synapse/
+      cp pyproject.toml README.rst build_rust.py Cargo.toml Cargo.lock /synapse/
+      pip3 install --prefix="/install" --no-deps --no-warn-script-location /synapse[all];
+      cp docker/start.py $CRAFT_PART_INSTALL/
+      chmod 755 $CRAFT_PART_INSTALL/start.py
+      sed -i 's/#!\/usr\/local\/bin\/python/#!\/usr\/bin\/python3/' $CRAFT_PART_INSTALL/start.py
+      cp -r docker/conf $CRAFT_PART_INSTALL/
+      cp -r /usr/local $CRAFT_PART_INSTALL/usr/
+      cp -r /install/local/* $CRAFT_PART_INSTALL/usr/local/
+      mkdir -p $CRAFT_PART_INSTALL/usr/local/attributemaps
+      chmod 755 $CRAFT_PART_INSTALL/usr/local/attributemaps
+    overlay-packages:
+      - ca-certificates
+  synapse-conf:
+    plugin: dump
+    source: attributemaps
+    organize:
+      login_ubuntu.py: /usr/local/attributemaps/login_ubuntu.py

synapse_rock/scripts/run_cron.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+
+"""
+The goal of this script is to serialize the environment passed by pebble to a file
+and then to start the cron service. We're doing that because the environment of the cron service
+is not passed to the commands started by it.
+An alternative would have been to write to /etc/profile and start the called cron scripts with a login shell.
+But we wanted to use python scripts and not pollute the environment of the users
+(Creating a specific user for the cron service would be an added complexity).
+"""
+
+import json
+import os
+
+if __name__ == "__main__":
+    file_path = "/var/local/cron/environment.json"
+    os.makedirs(os.path.dirname(file_path), exist_ok=True)
+
+    with open(file_path, "w") as file:
+        json.dump(dict(os.environ), file)
+
+    os.execv("/usr/sbin/cron", ["/usr/sbin/cron", "-f", "-P"])