Stephen B. wrote:
Hi All,
I’ve only been using Rails for a short time (working through the
‘Agile…’ book) but it’s already caught my interest so much i’m loathed
to go back to the PHP day job…
I know form experience, after doing some rails it make you really not
like PHP work.
There are a few things i’m slightly unsure about. First thing is
environments. Am I right in thinking that environments are just
concerning the state an application is in? i.e. development would have
more debugging etc.
Rails deafults to 3 environments, each of which should use a different
database.
DEVELOPMENT: As the name implies this is what you develop in. It has a
few advantages. First of all, almost all of your code is reloaded on
every request, meaning you can change things, refresh, and see tha
chnages without rebooting the server program. It also has robust error
reporting. If your app blows up you get a screen with the error and a
stack trace to help you debug.
PRODUCTION: This is what you run your app in when its live and launched.
Your code is cached, meaning its loaded when the server boots, and then
left in memory. This is much faster than reloading the entire framework
on each request, but it will not reflect change made to the code while
running, which for a live webapp is fine. Also errors are handled with
standard error codes and the guts of the application are not exposed.
So if you go to a page that doesn’t exist, you simply get “404” instead
of a routing error with a stack trace you would get in development mode.
TEST: Used for tests. Tests created in your test directory are run via
“rake” from command line. You usually wont ever have a webserver
running an app in test mode.
The other thing is concerning updates and fixes to a live site. The
application would be in production at that stage. If i needed to edit
source code, i assume i can just change the code on-the-fly. If i
needed to add a new column to a table for some reason, how would i
update the models to reflect the new schema?
Since sites in production mode used cached code you can’t just change
the code and reload. My process for updating a live site is usually as
follows.
Commit to subversion some change
svn up
rake migrate RAILS_ENV=production
killall lighttpd
lighttpd -f /home/lighttpd/lighttpd.conf
We simply update the code, run any pending migrations, then reboot the
webserver. The app should only be unavailable for a few seconds.
I think with a lot of this it’s my approach to things that may be the
problem. Learning rails is opening my mind up to a lot of concepts
that, while i really like, i’m not familier. I’d apprieciate any
comments on the above.
Cheers!
Steve
