docker: make compose work with cgroups (v2), conversion scripts/docs

docker-compose.yaml

@@ -3,12 +3,12 @@ services:
     build:
       context: ./
       dockerfile: docker/chatmail_relay.dockerfile
-      tags:
-        - chatmail-relay:latest
     image: chatmail-relay:latest
     restart: unless-stopped
     container_name: chatmail
-    cgroup: host # required for systemd
+    # Required for systemd — use only one of the following:
+    cgroup: host          # compose v2 only
+    # privileged: true    # compose v1 (not tested)
     tty: true # required for logs
     tmpfs: # required for systemd
       - /tmp

docker/cm_ini_to_env.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+"""Convert a chatmail.ini to a Docker .env file.
+
+Usage: python docker/cm_ini_to_env.py [chatmail.ini] [.env]
+
+Reads the ini file, extracts all non-default key=value pairs,
+and writes them as UPPER_CASE env vars suitable for docker-compose.
+"""
+
+import configparser
+import sys
+from pathlib import Path
+
+# Keys that only make sense for bare-metal deploys or are handled
+# separately by the Docker setup and should not appear in .env.
+SKIP_KEYS = set()
+
+# Keys that exist in .env but have a different name than the ini key.
+# ini_key -> env_key
+RENAMES = {}
+
+
+def read_ini(path):
+    """Return dict of key=value from [params] section."""
+    cp = configparser.ConfigParser()
+    cp.read(path)
+    if not cp.has_section("params"):
+        sys.exit(f"Error: {path} has no [params] section")
+    return dict(cp.items("params"))
+
+
+def read_defaults():
+    """Return dict of default values from the ini template."""
+    template = Path(__file__).resolve().parent.parent / "chatmaild/src/chatmaild/ini/chatmail.ini.f"
+    if not template.exists():
+        return {}
+    cp = configparser.ConfigParser()
+    cp.read(template)
+    if not cp.has_section("params"):
+        return {}
+    defaults = {}
+    for key, value in cp.items("params"):
+        # Template placeholders like {mail_domain} aren't real defaults.
+        if "{" not in value:
+            defaults[key] = value
+    return defaults
+
+
+def ini_to_env(ini_path, only_non_default=True):
+    """Yield (ENV_KEY, value) pairs from an ini file."""
+    params = read_ini(ini_path)
+    defaults = read_defaults() if only_non_default else {}
+
+    for key, value in sorted(params.items()):
+        if key in SKIP_KEYS:
+            continue
+        if only_non_default and key in defaults and value.strip() == defaults[key].strip():
+            continue
+        env_key = RENAMES.get(key, key.upper())
+        yield env_key, value.strip()
+
+
+def main():
+    ini_path = sys.argv[1] if len(sys.argv) > 1 else "chatmail.ini"
+    env_path = sys.argv[2] if len(sys.argv) > 2 else None
+
+    if not Path(ini_path).exists():
+        sys.exit(f"Error: {ini_path} not found")
+
+    lines = []
+    for env_key, value in ini_to_env(ini_path):
+        lines.append(f'{env_key}="{value}"')
+
+    output = "\n".join(lines) + "\n"
+
+    if env_path:
+        Path(env_path).write_text(output)
+        print(f"Wrote {len(lines)} variables to {env_path}")
+    else:
+        print(output, end="")
+
+
+if __name__ == "__main__":
+    main()

docker/files/setup_chatmail_docker.sh

@@ -67,7 +67,10 @@ git config --global --add safe.directory /opt/chatmail
 if [ "$RECREATE_VENV" = true ]; then
     rm -rf venv
 fi
+# Skip venv creation if it already exists
+if [ ! -x venv/bin/python ] || [ ! -x venv/bin/cmdeploy ]; then
     ./scripts/initenv.sh
+fi
 
 ./scripts/cmdeploy init --config "${INI_FILE}" $INI_CMD_ARGS $MAIL_DOMAIN || true
 bash /update_ini.sh

docs/DOCKER_INSTALLATION_EN.md

@@ -5,7 +5,13 @@
 - The Docker image is only suitable for amd64. If you need to run it on a different architecture, try modifying the Dockerfile (specifically the part responsible for installing dovecot).
 
 # Docker installation
-This section provides instructions for installing Chatmail using docker-compose.
+This section provides instructions for installing Chatmail using Docker Compose.
+
+**Note:** Docker Compose v2 is required (`docker compose`, not `docker-compose`) for its support of the `cgroup: host` option in `docker-compose.yaml` is only supported by Compose v2.
+[see documentation](https://docs.docker.com/engine/install/debian/#install-using-the-repository)
+```shell
+apt install docker-ce docker-compose-plugin docker.io- docker-compose-
+```
 
 ## Preliminary setup
 We use `chat.example.org` as the Chatmail domain in the following steps.
@@ -75,6 +81,9 @@ docker compose up -d # start service
 docker compose logs -f chatmail # view container logs, press CTRL+C to exit
 ```
 
+### venv creation
+The first container start takes longer because it creates the cmdeploy Python virtualenv at `/opt/chatmail/venv` (persisted on the host via volume mount). Subsequent starts reuse the existing venv. Set `RECREATE_VENV=true` in `.env` to force a rebuild if needed.
+
 6. After installation is complete, you can open `https://<your_domain_name>` in your browser.
 
 ## Using custom files
@@ -114,6 +123,50 @@ docker compose down
 docker compose up -d
 ```
 
+## Migrating from a bare-metal install
+
+If you have an existing bare-metal Chatmail installation and want to switch to Docker:
+
+1. Stop all existing services:
+
+```shell
+systemctl stop postfix dovecot doveauth nginx opendkim unbound acmetool-redirector \
+  filtermail filtermail-incoming chatmail-turn iroh-relay chatmail-metadata \
+  lastlogin mtail
+systemctl disable postfix dovecot doveauth nginx opendkim unbound acmetool-redirector \
+  filtermail filtermail-incoming chatmail-turn iroh-relay chatmail-metadata \
+  lastlogin mtail
+```
+
+2. Convert your existing `chatmail.ini` to the Docker `.env` format:
+
+```shell
+python3 docker/cm_ini_to_env.py /usr/local/lib/chatmaild/chatmail.ini .env
+```
+
+3. Copy persistent data into the `./data/` subdirectories:
+
+```shell
+mkdir -p data/chatmail-dkimkeys data/chatmail-acme data/chatmail
+
+# DKIM keys
+cp -a /etc/dkimkeys/* data/chatmail-dkimkeys/
+
+# ACME certificates and account
+rsync -a /var/lib/acme/ data/chatmail-acme/
+
+# Mail data
+rsync -a /home/ data/chatmail/
+```
+
+Alternatively, you can mount `/home/vmail` directly by changing the volume in `docker-compose.yaml`:
+
+```yaml
+- /home/vmail:/home/vmail
+```
+
+The three `./data/` subdirectories cover all persistent state. Everything else is regenerated by the `configure` and `activate` stages on container start.
+
 ## Forcing a full reinstall
 
 The Docker image bakes the install stage (binary downloads, package setup, chatmaild venv) into the image at build time. On container start, only the `configure` and `activate` stages run by default.