Hi Sourav, Could you confirm whether you were able to make HAProxy work with MQTT??
Baptiste On Fri, Sep 11, 2015 at 2:14 PM, Baptiste <[email protected]> wrote: > Hi Sourav, > > Thanks a lot for the mail and the screenshot. > That said, usually, when we ask for a capture, we mean a pcap file, not a > png one :) > It's fine, I have the information I need. > > I also used this documentation: > http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718037 > > >> Please note that the MQTT messages are carried on top of TCP. Also, as >> mentioned in previous mail, I am trying to load balance the traffic based on >> the topic mentioned in the MQTT message( 3rd line from end ) which means >> that all the traffic corresponding to a particular topic should be forwarded >> to a specific server only. > > > That's doable only in the following condition: > - the client speaks first (no server banner) > - the information is available in first session buffer > - the information is available always at the same place > > It seems MQTT meet the 3 rules above, so we may be able to do something. > >> So considering above requirement, I have the following questions : >> >> 1. Is MQTT already supported as an out of box feature? > > > No, MQTT is not supported out of the box. > >> >> 2. Is there a configurable hook/plugin through which above can be >> achieved? > > > You might be able to code a MQTT protocol parser in Lua. > You could even do MQTT routing to a specific farm based on the topic, but > load-balancing is an other story. > >> >> 3. If no configuration/plugins are available, how easy it would be to add >> the feature/code in order to retrieve payload information from TCP packets >> and parse it as par MQTT? > > > Very complicated, I'm afraid... > >> >> 4. What are main modules which I should look into in order to implement >> the same in case not yet implemented? >> > > Well, as I mentionned above, there might be some stuff we can do. > Please check > http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#req.payload_lv > > Following your capture, this fetch can be used to retrieve the whole topic: > req.payload_lv(1,1) => it fetch content in the TCP payload buffer whose size > is specified at byte 1 for 1 byte and data is stored right after the size. > > This fetch has the corresponding ACL to match against static patterns. > Imagine 3 topics: topic1, topic2, topic3, then you could do: > > frontend mqtt > [...] > use_backend bk_topic1 if { req.payload_lv(1,1),lower topic1 } > use_backend bk_topic2 if { req.payload_lv(1,1),lower topic2 } > use_backend bk_topic3 if { req.payload_lv(1,1),lower topic3 } > > backend bk_topic1 > [...] > > backend bk_topic2 > [...] > > backend bk_topic3 > [...] > > The same could be applied in a single backend, using the use-server > statement. > > I hope this help and this is enough. > > Be aware that once the TCP session has been forwarded to a server, then all > subsequent messages are going to be forwarded to this server, regardless of > the next topics set over the same connection. > To be routed again, a client must send next PUBLISH message over a new TCP > connection. > > Baptiste > > > > On Thu, Sep 10, 2015 at 7:58 PM, Baptiste <[email protected]> wrote: >> >> On Thu, Sep 10, 2015 at 4:05 PM, Sourav Das <[email protected]> >> wrote: >> > Hi, >> > >> > I have been going through the HAProxy documentation for my work which >> > deals >> > with scaling and load balancing for MQTT Brokers. >> > >> > However, I could not find any configuration regarding the Client >> > Affinity >> > where the routing of the MQTT traffic is done based on the topic present >> > in >> > the MQTT message. As MQTT is also carried over TCP, is it possible to >> > use a >> > pre-configured hook in HAProxy so that the traffic can be routed to the >> > appropriate server based on the MQTT topic. >> > >> > At present I am not able to find out any hook which enables this to be >> > done. >> > I am a bit curious to know whether the support of MQTT is planned in >> > future >> > releases of HAProxy. >> > >> > >> > Please let me know if this makes sense. >> > >> > Regards, >> > Sourav >> >> >> Hi Sourav, >> >> This would be doable only if the information can be retrived from the >> payload of the first request sent by the client. >> could you provide more information about how MQTT protocol works? Is >> there any server banner? >> A simple TCP dump containing an example of the message you want to >> route would be appreciated and allow us to deliver you an accurate >> answer. >> >> Baptiste >> >> >
