dhis2-users team mailing list archive

[Jason Phillips <jason@xxxxxxxx>]

Hibernate cache...?

I’m sorry, I don’t speak Norwegian.  The what, now?



I’ll Google when I get a chance, but for now, have no idea what you’re
talking about…  J

It does sound important, though…



Kind Regards,

*Jason Phillips*

[image: hisp]
*Information Systems / Infrastructure*

*Health Information Systems Program____________________________________*

eMail:               jason@xxxxxxxx
Tel/Fax:            +27 21 712 0170
Cell:                 +27 72 973 7250
Skype:             jason.n.phillips

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*From:* Bob Jolliffe [mailto:bobjolliffe@xxxxxxxxx]
*Sent:* Wednesday, 16 March 2016 2:24 PM
*To:* Lars Helge Øverland
*Cc:* Jason Phillips; DHIS 2 Users list
*Subject:* Re: [Dhis2-users] Load-balancing DHIS2 Webservers



I have not done this, but I imagine that hibernate cache replication
between instances is something that really needs to be done to have this
sort of scaling configuration work.



I do remember there was a brief flirtation with hazelcast before reverting
to ehcache.  Is anybody using ehcache in this way ie. for replication in a
clustering setup?



On 16 March 2016 at 12:22, Lars Helge Øverland <lars@xxxxxxxxx> wrote:

Hi Jason,



there is the concept of "sticky sessions" which should ensure that a user
is always sent to the same server throughout his session:



https://www.nginx.com/products/session-persistence/

http://nginx.org/en/docs/http/load_balancing.html



There are other issues with load balancing (session persistence in case a
server goes down, hibernate cache replication) but this could help.



regards,



Lars













On Tue, Mar 15, 2016 at 8:20 PM, Jason Phillips <jason@xxxxxxxx> wrote:

Aha!



A little more reading goes a long way…  ip_hash persistence appears to work
– I can log in, anyway.

For those of you interested, here’s the URL:
http://nginx.org/en/docs/http/ngx_http_upstream_module.html#ip_hash



If I have anything more relevant to share, I will…



Kind Regards,

*Jason Phillips*

[image: hisp]
*Information Systems / Infrastructure*

*Health Information Systems Program____________________________________*

eMail:               jason@xxxxxxxx
Landline:          +27 21 712 0170
Mobile:             +27 72 973 7250
Skype:             jason.n.phillips

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*From:* Jason Phillips [mailto:jason@xxxxxxxx]
*Sent:* Tuesday, 15 March 2016 8:34 PM
*To:* DHIS 2 Users list
*Subject:* Load-balancing DHIS2 Webservers



Hi, community (and Oslo team),



I am trying to set up a load-balanced DHIS2 web-server system; we have a
web server that’s getting slaughtered with incoming data, and we want to
distribute the load to other physical servers.  I’ve done some
experimentation, a fair amount of web-trawling, and using a dedicated nginx
virtual server, have (semi)successfully set up a load-balancing model like
so:





My problem is that going through the load-balancer, I appear to need some
kind of setting that will “keep” me at the Web-Server I first started with
– the load-balancer is set to round-robin, currently, with the following
settings:



upstream dhis2 {

        server webserver1.dhis.hisp.org;

        server webserver2.dhis.hisp.org;

        }



server {

        listen 80;

        server_name www.hisp.org hisp.org;



        location / {

                include /etc/nginx/proxy_params;

                proxy_pass http://dhis2;

        }

        location /staging {

                include /etc/nginx/proxy_params;

                proxy_pass http://dhis2;

        }

        location /training {

                include /etc/nginx/proxy_params;

                proxy_pass http://dhis2;

        }

}



What’s happening is that I attempt to log in, and get immediately switched
“round-robin” style to the second server for the post (promptly getting the
“forgot password?” prompt).
Nett result: I can’t log in…

If I log in to either one of the webservers directly, everything is fine
and dandy, but going through the LB is a no-go, so far.  (I have noticed
some interesting behaviour from two web servers connected to the same Db,
and would be keen to hear what input anyone has on that score – bad idea?
If so, why?  And what can be done to address the issues? – but I shall save
that for a separate post…)



Has anyone done any research/experimentation/development with a
load-balancing model of DHIS2 in a web-server context?  I would be most
interested to hear input.



Kind Regards,

*Jason Phillips*

[image: hisp]
*Information Systems / Infrastructure*

*Health Information Systems Program____________________________________*

eMail:               jason@xxxxxxxx
Landline:          +27 21 712 0170
Mobile:             +27 72 973 7250
Skype:             jason.n.phillips

This message and any attachments are subject to a disclaimer published at
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-- 

Lars Helge Øverland

Lead developer, DHIS 2

University of Oslo

Skype: larshelgeoverland

http://www.dhis2.org <https://www.dhis2.org/>




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