Merge #2017

2017: rspamd: get dkim keys via REST API instead of filesystem r=mergify[bot] a=ghostwheel42

## What type of PR?

enhancement

## What does this PR do?

rspamd now uses hashicorp's vault api v1 to get dkim keys and selectors for a domain.
this allows future enhancement (multiple keys) without reconfiguring and restarting rspamd.
it also makes mounting the /dkim volume into the rspamd container unnecessary.

### Related issue(s)

- improves and closes #2012 
- allows to implement key rotation using multiple selectors (see #1700)
- allows to implement dkim for alternate domains (see #1519)
- fixes and closes #1345 (selector transmitted by admin container is used)
- closes #1179 (no keys on disk)
- allows to implement key rotation from the outside (ie. via a helper script talking to some dns provider's api) (see #547)

## Prerequisites

- [X] In case of feature or enhancement: documentation updated accordingly
- [X] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/workflow.html#changelog) entry file.


Co-authored-by: Alexander Graf <ghostwheel42@users.noreply.github.com>

core/admin/mailu/internal/views/__init__.py

@@ -1,3 +1,3 @@
 __all__ = [
-    'auth', 'postfix', 'dovecot', 'fetch'
+    'auth', 'postfix', 'dovecot', 'fetch', 'rspamd'
 ]

core/admin/mailu/internal/views/rspamd.py

@@ -0,0 +1,30 @@
+from mailu import models
+from mailu.internal import internal
+
+import flask
+
+def vault_error(*messages, status=404):
+    return flask.make_response(flask.jsonify({'errors':messages}), status)
+
+# rspamd key format:
+# {"selectors":[{"pubkey":"...","domain":"...","valid_start":TS,"valid_end":TS,"key":"...","selector":"...","bits":...,"alg":"..."}]}
+
+# hashicorp vault answer format:
+# {"request_id":"...","lease_id":"","renewable":false,"lease_duration":2764800,"data":{...see above...},"wrap_info":null,"warnings":null,"auth":null}
+
+@internal.route("/rspamd/vault/v1/dkim/<domain_name>", methods=['GET'])
+def rspamd_dkim_key(domain_name):
+    domain = models.Domain.query.get(domain_name) or flask.abort(vault_error('unknown domain'))
+    key = domain.dkim_key or flask.abort(vault_error('no dkim key', status=400))
+    return flask.jsonify({
+        'data': {
+            'selectors': [
+                {
+                    'domain'  : domain.name,
+                    'key'     : key.decode('utf8'),
+                    'selector': flask.current_app.config.get('DKIM_SELECTOR', 'dkim'),
+                }
+            ]
+        }
+    })
+

core/rspamd/conf/arc.conf

@@ -1,4 +1,6 @@
-try_fallback = true;
+try_fallback = false;
-path = "/dkim/$domain.$selector.key";
-selector = "dkim"
 use_esld = false;
+allow_username_mismatch = true;
+use_vault = true;
+vault_url = "http://{{ ADMIN_ADDRESS }}/internal/rspamd/vault";
+vault_token = "mailu";

core/rspamd/conf/dkim_signing.conf

@@ -1,4 +1,6 @@
-try_fallback = true;
+try_fallback = false;
-path = "/dkim/$domain.$selector.key";
 use_esld = false;
 allow_username_mismatch = true;
+use_vault = true;
+vault_url = "http://{{ ADMIN_ADDRESS }}/internal/rspamd/vault";
+vault_token = "mailu";

core/rspamd/start.py

@@ -11,6 +11,7 @@ log.basicConfig(stream=sys.stderr, level=os.environ.get("LOG_LEVEL", "WARNING"))
 # Actual startup script
 
 os.environ["REDIS_ADDRESS"] = system.get_host_address_from_environment("REDIS", "redis")
+os.environ["ADMIN_ADDRESS"] = system.get_host_address_from_environment("ADMIN", "admin")
 
 if os.environ.get("ANTIVIRUS") == 'clamav':
     os.environ["ANTIVIRUS_ADDRESS"] = system.get_host_address_from_environment("ANTIVIRUS", "antivirus:3310")

towncrier/newsfragments/2017.enhancement

@@ -0,0 +1 @@
+rspamd: get dkim keys via REST API instead of filesystem