When I was doing this, I read (and re-read) everything I could find: apache
docs, tutorials, mailing lists, articles, stackoverflow, etc. That was all
helpful for understanding the big picture, but still didn't prepare me for what
I had to do in my case.
* I tried to configure reverse proxy httpd.conf like following:
>From your directives, you have told your proxy server how to 'route' HTTP
>requests. Now, you need the content on the client to request resources that
>match your ProxyPass rules.
As a rough guide of how to approach this:
1. Open the dev tools in your Chrome browser (F12) and load a page from your
weblogic server.
2. Examine the HTML, CSS, JS, HTTP headers for references to your webserver.
* I expect you will see references like: http://WEBSERVERHOST:8080/f5url
instead of http://WEBSERVERHOST:8080/appl1/f5url
3. As a POC, simply manually edit (using dev tools) one of those URLs to
match what your reverse-proxy is expecting
* Now, select that modified URL on your webpage and watch the protocol
exchange with your proxy server
* If that works, then you will have a better idea of the other things
your reverse-proxy has to do
Some random things to keep an eye out for...
There are a bunch of Apache directives that help with these substitutions.
Look at ProxyHTMLURLMap and ProxyHTMLEvents. Though, I find for complex apps
ProxyHTMLURLMap was limiting so I use the 'substitute' module instead. While
'substitute' has proven to be more versatile, it comes with a cost of
additional complexity.
For simple webapps, you can probably get away with ProxyHTMLURLMap. Though, I
doubt weblogic is simple. In any case, I'd recommend start with
ProxyHTMLURLMap and only introduce 'substitute' if needed.
Other things... Look at your cookie path. If it contains references, then
read about when to use ProxyPassReverseCookiePath / /app1
You also need to set:
ProxyHTMLEnable On
If you decide to use the substitute module, then you will likely need things
like:
SetOutputFilter
AddOutputFilterByType SUBSTITUTE text/javascript text/html text/css
That's all for now.
Matt.
From: Sontakke, Sachin (NonEmp) <[email protected]>
Sent: Friday, 24 January 2020 1:48 AM
To: [email protected]; Muggeridge, Matt <[email protected]>
Subject: RE: query on apache reverse proxy
Thanks a lot Matt for taking time in understanding my challenge and replying to
it.
I tried to configure reverse proxy httpd.conf like following:
First I have added modules using -
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so
And then updated virtualhost using -
<VirtualHost *:80>
ProxyPass /app1 http://WEBSERVERHOST:8080/app1/<http://WEBSERVERHOST:8080/app1/>
ProxyPass /console
http://WEBSERVERHOST:8080/console/<http://WEBSERVERHOST:8080/console/>
ProxyPassReverse /app1
http://WEBSERVERHOST:8080/app1/<http://WEBSERVERHOST:8080/app1/>
ProxyPassReverse /console
http://WEBSERVERHOST:8080/console/<http://WEBSERVERHOST:8080/console/>
</VirtualHost>
So when F5 URL is hit, user request comes to apache reverse proxy and then it
is forwarded to WEBSERVERHOST:8080 using above config in virtualhost.
Then WEB SERVER forwards it to WebLogic (app-tier). But then next subsequent
request URLs are changed to
http://WEBSERVERHOST:8080/<http://WEBSERVERHOST:8080/> instead of F5.
Please can you verify if above config is ok or I need something. I do not wish
to pour any work on you - only reply if you find something I am missing which
is very obvious.
Again, thank you very much.
SachinS
From: Muggeridge, Matt
<[email protected]<mailto:[email protected]>>
Sent: Wednesday, January 22, 2020 5:47 PM
To: [email protected]<mailto:[email protected]>
Subject: [users@httpd] RE: query on apache reverse proxy
** [EXTERNAL EMAIL]: Do not click links or open attachments unless you
recognize the sender and know the content is safe. **
I'll use your terminology of "Web Server" and "Apache Reverse Proxy" to refer
to the two entities of interest here.
>But after adding apache reverse proxy, when the client hits the F5 URL - all
>the subsequent requests are going to Web Server on 8080 port and getting
>served from there instead of going via Apache Reverse Proxy.
In brief, your "Apache Reverse Proxy" has to dynamically modify the content
sent to the client, with references that point back at your "Apache Reverse
Proxy".
E.g. your "Web Server" will serve pages containing hrefs that point back at it,
e.g. href=https://webserver:8080/f5-url<https://webserver:8080/f5-url>. The
"Apache Reverse Proxy" must substitute the href to point at itself instead,
e.g.
href="https://proxy-server:80/webserver/f5-url<https://proxy-server:80/webserver/f5-url>".
You configure the reverse proxy so that when it sees a HTTP request for a
page containing "/webserver", it knows to proxy that request to
https://webserver:8080<https://webserver:8080>. (There are many ways to
configure this.)
There is a lot more to this, since these substitutions have to happen
*everywhere* an action would cause the client-browser to open a page to the
"Web Server" or send content referencing the "Web Server". So, you have to
perform substitutions in the html, css, javascript, http headers (e.g.
cookies), etc. Getting all the substitutions correct for your web-application
is quite the art. It will have to be validated each time you upgrade your
backend web-application too.
You are in for a journey. Start small, preferably with a simple web-app and
grow in complexity from there. Some of these reverse-proxy scripts become
quite complex and have dependencies on ordering of substitutions and a bunch of
other challenges that you will only discover through trial-and-error. There
are also many ways to substitute things, so that also requires experimenting to
learn what works best for your application.
There is a lot more to configuring an application to use the reverse-proxy than
what I say here. Be meticulous and patient.
Good luck.
Matt.
From: Sontakke, Sachin (NonEmp)
<[email protected]<mailto:[email protected]>>
Sent: Thursday, 23 January 2020 8:07 AM
To: [email protected]<mailto:[email protected]>
Subject: [users@httpd] query on apache reverse proxy
I have a question regarding apache reverse proxy setup.
We have a web application running on WebLogic; it's a typical 3 tier
application.
Flow is as follows:- Client=> F5 load balance=> Web Server listening on 80=>
WebLogic App=> Oracle DB.
Due to certain requirement we need to introduce Apache reverse proxy in front,
so now flow will look like:-
Client=> F5 load balance=> Apache Reverse Proxy listening on 80=> Web Server
listening on 8080=> WebLogic App=> Oracle DB.
But after adding apache reverse proxy, when the client hits the F5 URL - all
the subsequent requests are going to Web Server on 8080 port and getting served
from there instead of going via Apache Reverse Proxy.
NOTE: Apache reverse proxy and Web server both are running on the same Host.
May I know what could have gone wrong or any way I can troubleshoot this issue?
Thanks,
Sachin
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