Moving the wiki

[Michael Scherer]

Le lundi 20 octobre 2014 à 11:05 -0400, Barak Korren a écrit :
> There has been some talk recently about moving the ovirt.org wiki to a dedicated VM in the PHX data-center.
> I would like to open this up to some discussion.
> Here is the current situation as far as I could gather, more info and comment are welcome.
> 
> What do we have now
> -------------------
> MediaWiki (Which version? eedri told me its a rather old one)
1.18 ( or 1.19 )

> PHP (Which version?)
5.3.3

> MySQL 5.1
> All running in a single (?) 'large' OpenShift gear.
yes

> Our OpenShift account is classified as 'silver' (is it?) thereby granting us gears with 6GB storage instead 
> of 1GB) 
yes. I think we even already have 10G

> Why do we want to migrate?
> --------------------------
> We occasionally have a problem where the site goes down. This seems to be caused by one of:
> 1. The OpenShift gear runs out of space
> 2. The MySQL DB gets stuck with no errors in the logs (Does restarting it resolve it?)

it usually was out of memory issue.

besides the problem, one reason to go to a more traditional setup for me
is that, being traditional, we have more freedom. For example,
installing varnish directly, having access to log without a middleman,
ease of backup.

And the capacity to use vanilla mediawiki.

> Why not to migrate?
> -------------------
> 1. Migrating the wiki to PHX VM will make the infra team have to manage the wiki hosting infrastructure. 
>    While one may claim that this is not complicated and that this work needs to also be done when the wiki 
>    is hosted on OpenShift, there are still many things that the OpenShift maintainers do for us such as:
>    - Keeping the webservers updated

there is just yum upgrade -y to do. I do not see that much as a
hindrance.

>    - Managing selinux

There is nothing to manage, selinux work out of the box on RHEL.
Also, due to the nature of openshift, the policy will only protect the
host, but you would still be able to access network and this kind
access. While with our own setup, we can have a tailored policy or
firewall.

>    - Enablign automatic scale-up

We have no scale up for that, and due to mediawiki itself, we either
have to patch it to not use the filesystem ( people suggested to use s3
), or wait until fs is shared on openshift. 

> 2. There are security concerns with having a public-facing (outdated?) PHP application running on a VM in 
>    the same network where our build and CI servers run. (I might be too paranoid here, having had one of my
>    own sites defaced recently, but OpenShift makes it easy to create a new gear and git push the code to 
>    get back up and running, with our own VM, forensics and cleanup might be more complicated) 

I do not see how openshift will be easier. We can make a snapshot of the
VM in ovirt too, afaik, so the forensic wouldn't be harder ( and in
fact, would preserve the memory, which is rather important ).

> Known infra issues with existing configuration
> ----------------------------------------------
> 1. The MySQL DB was setup without 'innodb_file_per_table' turned on, this can impact DB performance. To 
>    resolve this, one need to dump and import the entire DB.
> 
> Things we can try (Besides migrating)
> -------------------------------------
> 1. Place ovirt.org behind a caching reverse-proxy CDN like cloudflare, that can mask some of our downtime.
> 2. Dump and import the DB to rebuild and optimize the DB files
we need to have a bit more space to operate, that's the issue. 

> 3. Rebuild the wiki in a new gear to get rid of possibly accumulating cruft
> 4. Upgrade the MySQL to 5.5 (Or whatever latest supported by OpenShift)
We can't do that easily. 

> 5. Upgrade MediaWiki
We would have to rediff some of the patchs, I would rather start from
scratch.

> 6. Add a redundant MySQL/Wiki server using MySQL replication
Not working due to gears isolation. IE, 2 gears cannot communicate that
easily. This would be doable with a special embedded cartridge.

> 7. Trim the wiki history (AFAIK MediaWiki saves every edit ever, but one can maybe use export/import to get
>    rid of some)  
Why drop history, that's like dropping git history :/


> 8. Try to come up with a way to spread the Wiki across multiple OpenShift gears
Rather hard to do, especially since we are not root.

> 9. Tune DB parameters (is it possible to do on OpenShift?)
No, since the mysql is managed by openshift we are not root.

> I eagerly await your comments,

I still think the easiest way is to host our own setup.
-- 
Michael Scherer
Open Source and Standards, Sysadmin
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