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cbrdy's avatar
cbrdy
Icon for Nimbostratus rankNimbostratus
Oct 02, 2013

Website shows 502: Proxy error

Hi,

 

We have an issue in our DR environment which we think is caused by F5 WA module.

 

Note: PROD and DR F5 config are completely in sync. PROD env is working very well.

 

Set-up: We have apache HTTP and tomcat instances behind F5 (same F5 for both) and WA is also configured for this website. If the site is accessed bypassing tomcat pool (directly connecting to single instance of tomcat) the site works fine but if the same site is accessed through tomcat pool (through F5) we are getting proxy error.

 

So what we have done is, configured apache instance to bypass F5 tomcat pool and invalidated cache. After invalidating, we configured apache to go through F5. This time the site works absolutely fine. After sometime (15-30 min later), the site again starts to show proxy error.

 

My questions: 1. Is WA causing this issue ? 2. Can we force invalidate all the cache ? What commands need to run on F5 to do this ?

 

3 Replies

  • JRahm's avatar
    JRahm
    Icon for Admin rankAdmin
    Oct 02, 2013

    not sure about WA causing a 502 error, I'd suggest taking some packet captures on both sides of the BIG-IP and do some analysis on that front. Regarding the invalidation, that is done by application, and can be done from the command line in tmsh. On 11.4, that command is tmsh::modify wam application content-expiration-time now, though I think it is slightly different on earlier versions.

     

    If you want to have a URL interface to invalidating cache, I wrote an article on a potential configuration using iCall, introduced in 11.4:

     

  • cbrdy's avatar
    cbrdy
    Icon for Nimbostratus rankNimbostratus
    Oct 02, 2013

    thanks for replying Jason. My F5 version: 9.4.8 We do have a tool to invalidate cache using perl script. I wanted to know if there is any difference between invalidation done from F5 or through script (script uses query string to invalidate cache).

     

    Let's say if HTTP status code is not 200,301 or 302. Can WA do cache invalidation ?

     

    • JRahm's avatar
      JRahm
      Icon for Admin rankAdmin
      Oct 02, 2013
      you can definitely create invalidation rules in 9.4.x, but I'm not sure to what granularity, it's been several years since I've touched a 9.x box. The chapter on invalidation rules for 9.x is here: http://support.f5.com/kb/en-us/products/wa/manuals/product/WA_PolicyMgmtGuide_9_4_2/invalidt.html?sr=32261697