feat!: introduce configurable system limits to reject new address creation and limit imap/smtp connections.

The default values are geared towards minimal-requirements server.
If you have a big server, you will need to set chatmail.ini parameters.

cmdeploy/src/cmdeploy/deployers.py

@@ -356,6 +356,8 @@ class ChatmailVenvDeployer(Deployer):
     def __init__(self, config):
         self.config = config
         self.units = (
+            # doveauth must restart when chatmaild/ini file changes
+            "doveauth",
             "chatmail-metadata",
             "lastlogin",
             "chatmail-expire",

cmdeploy/src/cmdeploy/dovecot/deployer.py

@@ -34,7 +34,7 @@ class DovecotDeployer(Deployer):
     def __init__(self, config, disable_mail):
         self.config = config
         self.disable_mail = disable_mail
-        self.units = ["doveauth"]
+        self.units = []
 
     def install(self):
         arch = host.get_fact(Arch)

cmdeploy/src/cmdeploy/dovecot/dovecot.conf.j2

@@ -37,7 +37,7 @@ default_client_limit = 20000
 # the following warning will be logged:
 #   Warning: service(imap): process_limit (1024) reached, client connections are being dropped
 service imap {
-  process_limit = 50000
+  process_limit = {{ config.max_imap_connections }}
 }
 
 {% if config.privacy_mail %}

cmdeploy/src/cmdeploy/mtail/delivered_mail.mtail

@@ -28,6 +28,13 @@ counter created_nonci_accounts
   }
 }
 
+# doveauth refusing new addresses because a chatmail.ini
+# system resource limit is exceeded.
+counter rejected_registrations
+/registration rejected: / {
+  rejected_registrations++
+}
+
 counter postfix_timeouts
 /timeout after DATA/ {
   postfix_timeouts++

cmdeploy/src/cmdeploy/postfix/master.cf.j2

@@ -18,7 +18,7 @@ smtp      inet  n       -       y       -       -       smtpd
   -o smtpd_tls_mandatory_protocols=>=TLSv1.2
   -o smtpd_proxy_filter=127.0.0.1:{{ config.filtermail_smtp_port_incoming }}
   -o smtpd_relay_restrictions=reject_unauth_destination
-submission inet n       -       y       -       5000    smtpd
+submission inet n       -       y       -       {{ config.max_smtp_connections }}    smtpd
   -o syslog_name=postfix/submission
   -o smtpd_tls_security_level=encrypt
   -o smtpd_tls_mandatory_protocols=>=TLSv1.3
@@ -32,9 +32,9 @@ submission inet n       -       y       -       5000    smtpd
   -o smtpd_sender_restrictions=$mua_sender_restrictions
   -o smtpd_recipient_restrictions=
   -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
-  -o smtpd_client_connection_count_limit=1000
+  -o smtpd_client_connection_count_limit={{ config.max_smtp_connections // 5 }}
   -o smtpd_proxy_filter=127.0.0.1:{{ config.filtermail_smtp_port }}
-smtps     inet  n       -       y       -       5000    smtpd
+smtps     inet  n       -       y       -       {{ config.max_smtp_connections }}    smtpd
   -o syslog_name=postfix/smtps
   -o smtpd_tls_wrappermode=yes
   -o smtpd_tls_security_level=encrypt
@@ -48,7 +48,7 @@ smtps     inet  n       -       y       -       5000    smtpd
   -o smtpd_sender_restrictions=$mua_sender_restrictions
   -o smtpd_recipient_restrictions=
   -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
-  -o smtpd_client_connection_count_limit=1000
+  -o smtpd_client_connection_count_limit={{ config.max_smtp_connections // 5 }}
   -o smtpd_proxy_filter=127.0.0.1:{{ config.filtermail_smtp_port }}
 #628       inet  n       -       y       -       -       qmqpd
 pickup    unix  n       -       y       60      1       pickup