Unfortunately 'stunneling everything' is not really possible. Stunnel acts like a proxy service ... in the sense that the Stunnel client (on your log producer, or log consumer) has to be explicitly configured to connect to an exact endpoint (ie, kafka1.mydomain.com:1234) -- or multiple endpoints, that are randomly selected by stunnel.
In a few cases you can use Stunnel as an SSL offloader for certain protocols, but thats done on the server-side... ie, in front of a Postgres server, so that Stunnel can do the encryption rather than Postgres itself. It would make a bit of a difference I think if our log producers were the only ones that needed to be able to talk to 'all' of the Kafka nodes. We could do something where we ship logs via an encrypted TCP session to some group of Kafka "log funnel" machines, where they can reach the Kafka servers directly and dump the log data. Maybe. I'm still digging around, but I'm really surprised this hasn't been a larger topic of discussion. If Kafka natively allowed a single connection through a single server to reach all of the other servers in the farm, it would be far easier to secure and encrypt the communication. ElasticSearch and RabbitMQ are good examples of this model. --Matt On Apr 22, 2013, at 12:21 PM, Scott Clasen <sc...@heroku.com> wrote: > I think you are right, even if you did put an ELB in front of kafka, it > would only be used for getting the initial broker list afaik. Producers and > consumers need to be able to talk to each broker directly, and also > consumers need to be able to talk to zookeeper as well to store offsets. > > Probably have to stunnel all the things. Id be interested in hearing how > it works out. IMO this would be a great thing to have in kafka-contrib. > > > > On Mon, Apr 22, 2013 at 11:31 AM, Matt Wise <m...@nextdoor.com> wrote: > >> Hi there... we're currently looking into using Kafka as a pipeline for >> passing around log messages. We like its use of Zookeeper for coordination >> (as we already make heavy use of Zookeeper at Nextdoor), but I'm running >> into one big problem. Everything we do is a) in the cloud, b) secure, and >> c) cross-region/datacenter/cloud-provider. >> >> We make use of SSL for both encryption and authentication of most of our >> services. My understanding is that Kafka 0.7.x producers and consumers >> connect to Zookeeper to retrieve a list of the current Kafka servers, and >> then make direct TCP connections to the individual servers that they need >> to to publish or subscribe to a stream. In 0.8.x thats changed, so now >> clients can connect to a single Kafka server and get a list of these >> servers via an API? >> >> What I'm wondering is whether we can actually put an ELB in front of *all* >> of our Kafka servers, throw stunnel on them, and give our producers and >> clients a single endpoint to connect to (through the ELB) rather than >> having them connect directly to the individual Kafka servers. This would >> provide us both encryption of the data during transport, as well as >> authentication of the producers and subscribers. Lastly, if it works, it >> would provide these features without impacting our ability to use existing >> kafka producer/consumers that people have written. >> >> My concern is that the Kafka clients (producers or consumers?) would >> connect once through the ELB, then get the list of servers via the API, and >> finally try to connect directly to one of those Kafka servers rather than >> just leveraging the existing connection through the ELB. >> >> Thoughts? >> >> --Matt
