Scalable mail cluster
This is one way to build a scalable mail infrastructure. Besides
GlusterFS, the performance is pretty good.
"Business Case" for this setup:
- Postfix, because it is written by a Dutchman and it supports the Proxy Protocol. Proxy protocol will preserve the original IP address and forward that to the back-end. The original IP address is needed for DNS-based blacklisting of spammers.
- HAProxy, because it supports/invented the Proxy Protocol
- GlusterFS, because it is a cool way to experiment with a clustered file-system and easy to setup
- Lighttpd, because it is not Apache
- Dovecot, OpenLDAP and Bind are just de facto standard applications
digraph {
label="Scalable Mail Cluster";
modem [label="NAT"; shape="rect"];
internet -> modem;
modem -> revproxy;
modem -> imap;
subgraph cluster_1 {
label="load balancer";
style="bold";
color="brown";
revproxy [label="HAProxy"; shape="box3d"];
}
revproxy -> smtp0;
revproxy -> smtp1;
subgraph cluster_025 {
label="SMTP";
style="bold";
color="brown";
smtp0 [label="Postfix"; shape="box3d"];
spamd0 [label="spamd"];
smtp0 -> spamd0;
spamd0 -> smtp0;
}
subgraph cluster_125 {
label="SMTP n";
style="bold,dashed";
color="brown";
smtp1 [label="Postfix"; shape="box3d"; style="dashed"];
spamd1 [label="spamd", style="dashed"];
smtp1 -> spamd1 [style="dashed"];
spamd1 -> smtp1 [style="dashed"];
}
smtp0 -> ldap;
smtp1 -> ldap [style="dashed"];
subgraph cluster_9 {
label="GlusterFS";
style="bold";
color="green";
maildir [shape="folder"];
}
smtp0 -> maildir;
smtp1 -> maildir;
smtp0 -> dns [lhead=cluster_6];
smtp1 -> dns [lhead=cluster_6; style="dashed"];
imap -> maildir;
subgraph cluster_143 {
label="IMAP";
style="bold";
color="brown";
imap [label="dovecot"; shape="box3d"];
}
subgraph cluster_53 {
label="RBL / DNSBL";
style="bold";
color="brown";
dns [label="bind"; shape="box3d"];
}
subgraph cluster_89 {
label="LDAP";
style="bold";
color="brown";
ldap [label="openldap"; shape="box3d"];
}
imap -> ldap [lhead=cluster_8];
}
