[Clojure] Assuring avalaibility of ring web apps

Hi,

Currently I am using noir for developing web apps. I am deploying them on an
EC2 server, by running lein trampoline run in the project directory. I also
have a nginx in front of it which is handling serving of static files.

I have never had the apps crash, however recently on app was down on one
fine morning, which was easily restarted ueing lein. How do others monitor
and deploy clojure web apps in production? Is there a lein plugin which can
monitor and restart the app if it is down ( such as nodejs's forever) ?

Thanks,
Murtaza


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On Wed, May 16, 2012 at 3:13 AM, Murtaza Husain wrote:
Currently I am using noir for developing web apps. I am deploying them on an
EC2 server, by running lein trampoline run in the project directory. I also
have a nginx in front of it which is handling serving of static files.

I have never had the apps crash, however recently on app was down on one
fine morning, which was easily restarted ueing lein. How do others monitor
and deploy clojure web apps in production? Is there a lein plugin which can
monitor and restart the app if it is down ( such as nodejs's forever) ?

I'm not personally using this but people I trust recommend it highly.
It has a free option plus fairly reasonable monthly options.

http://www.pingdom.com/

We use a similar service: cloudkick

We have some custom plugins that we've written for it (to monitor
RabbitMQ consumers and queue sizes -- we have had consumers die and
need to be restarted).

As you are, we are using Nginx. We have it set up to serve static
content and act as a load balancer and to do SSL termination. We have
a cluster of app servers set up behind this Nginx load balancer.
Having multiple app servers helps significantly with issues like a
single box going out. We have 3 configurations for the load balancer:
an A, a B and A+B. Where each has 50% of the app servers configured.
Nginx handles any one of the app servers being down, and we perform
releases, we split the cluster in to A, deploy to the boxes in B, wait
for the JVMs to warm up, the flip A and B and release to the A
partition. When those JVMs have warmed up we put them all back into
rotation (A+B). We use a symlink to point to the 3 configurations and
do a HUP on Nginx to have it reload its configuration without dropping
any connections.

We're not on AWS yet, if we were I think the same would be
accomplished with ELB instead of Nginx.

I think this is a pretty common set up -- we are following the books:
Scalable Internet Architectures, and Release IT (I highly recommend
both of those books).


Regards,

Kyle

--
Twitter: @kyleburton
Blog: http://asymmetrical-view.com/
Fun: http://snapclean.me/

On Wed, May 16, 2012 at 3:13 AM, Murtaza Husain wrote:
Is there a lein plugin which can
monitor and restart the app if it is down ( such as nodejs's forever) ?