I am running a Rails 3.0.9 app on Heroku's Cedar stack and have S3 serving static assets. In my production.rb file, there was a config set to:
config.serve_static_assets = false
If I change this to true, will it serve cached content quicker, or should I leave it as is?
The answer from Rafal is not strictly correct as essentially it comes down to what stack and what version of Rails you choose to run in your application.
With Rails 3.0 on the Bamboo stack there is a Varnish cache which sits in front of the Thin processes that Heroku run. This caches any static assets and returns them without hitting your application.
With Rails 3.0 on the Cedar stack there is no Varnish cache. Therefore all requests will be hitting your Rails process regardless of whether they are static or not.
With Rails 3.1 which should be on Cedar Heroku will try to run a rake assets:precompile as part of the slug compilation process. If this fails for any reason it will inject some code into your slug meaning that static assets are compiled and served at at run time.
There is a Rails 3.1 document on the dev center which is particularly useful regarding this: http://devcenter.heroku.com/articles/cdn-asset-host-rails31
So, if you're looking for the correct setting bear this in mind. However, before you do that, notice that Heroku will alter this setting as they see fit when you do your deploy, so any setting that you do put in will be overwritten anyway during the slug compilation. Therefore it doesn't really matter what you put in here.
(and for the record, Heroku uses Nginx, you just don't tend to see it)
From rails guide:
config.serve_static_assets configures Rails itself to serve static assets. Defaults to true, but in the production environment is turned off as the server software (e.g. Nginx or Apache) used to run the application should serve static assets instead. Unlike the default setting set this to true when running (absolutely not recommended!) or testing your app in production mode using WEBrick. Otherwise you won´t be able use page caching and requests for files that exist regularly under the public directory will anyway hit your Rails app.
Hope this helps.
Related
I have an action, that generates a PDF files and save it in the /public/output.pdf.
When I set
config.serve_static_assets = false
this file can't be found.
What's wrong ?
From the documentation:
"config.serve_static_assets configures Rails itself to serve static
assets. Defaults to true, but in the production environment is turned
off as the server software (e.g. Nginx or Apache) used to run the
application should serve static assets instead. Unlike the default
setting set this to true when running (absolutely not recommended!) or
testing your app in production mode using WEBrick. Otherwise you won´t
be able use page caching and requests for files that exist regularly
under the public directory will anyway hit your Rails app."
Which means that if you set that to false Rails will not serve any assets from your public folder as it is assumed that a front-end web server (apache/nginx) will handle it. This lessons the load on Rails as the front-end server is much, much more efficient at serving files directly.
After testing, I came to this conclusion:
1) when using the command
rails s -e production
Rails will only serve the statics files. Any other file created after you compile your assets will not be found.
To handle this, you need to execute your application under a web server like Apache, Nginx or other. These web servers will serve this files for you.
This looks to be obvious, but not for a beginner.
I have been developing ruby on rails application since some couple of months. I use the default WEBrick server to run the applications. And I found that when I start the WEBrick server in the development and production modes, the server works more speed for production mode than for the development mode.
Is there any specific reason behind that? Can anybody explain me?
In production mode, a server loads code into the cache, which makes things quick. However, that's not the case in development mode (since you don't want to restart your webrick every time you made a change). Every request loads the according code again, which takes a bit of time.
And the most of all time-eaters is the asset pipeline. In production, you get a compiled version of your assets (javascripts and css) in maybe one or two requests. In development, you get them split, for debugging purpose (based on your environment settings, of course). And because a browser does not handle all requests simultaneously, some assets are loaded after other ones are finished loading. You can watch this behaviour with e.g. firebug's network console. That means: the more assets you have, the longer your page takes to load in development mode.
In dev mode classes are not cached, so Rails reloads all the classes each time you refresh. Also, asset compilation is not done in development (by default), so Rails reloads all the assets (CSS, Javascript etc) each time you refresh.
The difference is between 2 environments. In Rails, there are several environment. Each has his own database configuration and Rails options.
You can use the Rails.env variable to made some different change with particular environment.
By default, the development environment is without all cache and activate the auto-reloading. The production environment is with all cache.
But if you want you can make a production environment like development or development environment like production.
You can add some new specific environment too.
Creating new Environment:
Assuming you want create the hudson environment.
Create a new environment file in config/environments/hudson.rb.
You can start by cloning an existing one, for instance config/environments/test.rb.
Add a new configuration block in config/database.yml for your environment.
That's all.
Now you can start the server
ruby script/server -e hudson
Run the console
ruby script/server hudson
And so on.
So the question basically boild down to this:
How do you efficiently handle changing assets in a production rails environment without the need to restart the server?
The problem we're experiencing is, we have to restart the Thin server that runs the app in order for the updated javascript files to be served.
Some background:
Right now we're generating data from a couple of long running tasks into javascript files once an hour so we can use it in our Rails app.
To be clear, we update/overwrite existing files, not adding new ones.
After generation we run these commands in order to re-precompile all the assets.
bundle exec rake assets:precompile
bundle exec rake rails_group=assets assets:clean RAILS_ENV=production
Still after clearing the browser cache and reloading the page we're being served the old assets.
Have you guys made any similar experiences; what did you do to work around it?
PS. Happy holidays to you all!
So, what we ended up doing is basically letting rails also serve static assets by setting
config.serve_static_assets = true
in config/environments/production.rb
and just putting the frequently changing javascript data files into a directory structure under public/.
This works grate since it also separates assets and data into different locations.
According to the Rails guide:
6 How Caching Works Sprockets uses the default Rails cache store to
cache assets in development and production.
Rails is going to cache your assets unless you tell it to not cache them. The whole point of the asset pipeline is to serve assets as quickly as possible by encouraging browsers and servers and the rails servers themselves to cache the assets.
If your use case involves redoing assets very often, maybe the asset pipeline isn't for you.
How much ruby code deals with serving static content out of public? Does it pass through the rails app at all? Does it use Rack::Static?
Rails doesn't use Rack::Static, it has its own version, ActionDispatch::Static. You should see it if you run rake middleware.
This is only added to the Rails middleware stack if config.serve_static_assets is true. This setting defaults to true, but the default generated config/environments/production.rb turns if off.
The idea is that during development you have a simple single process that you can run and check everything is working and where performance isn't an issue, but when you deploy to production you configure your webserver (usually Apache or Nginx) to serve the static files as it is much better at that than Ruby.
If you use Heroku, their latest Cedar stack doesn't use a separate webserver for static files, so as part of the deploy process they inject a Rails plugin to serve static assets. All this plugin does is set serve_static_assets to true.
It depends. If you're using something like phusion passenger to run your app, its default behavior is to use Apache directly and skip rails for any static content. If you're using webrick (rails server) it's going to use a lot more rails/rack code to do the static serving.
A note though, if you're using apache/nginx with passenger: in production mode, since the default is to let apache serve all static content, you will need to run rake assets:precompile on the application prior to launching it in apache, or the static content doesn't get put where it needs to be for apache to get it quickly, and in a prod-ready form.
I'm learning Ruby on Rails. At the moment I'm just running my site locally with rails server in the OS X Terminal. What changes when a Rails site is run on a production box?
Is the site still started with rails server?
Any differences with how the db is setup?
Note: I'm running Rails 3.
A rails app can be run in production calling rails server -e production, although 99% of the time you'll be serving on something like passenger or thin instead of WEBrick, which means there's a different command to start the server. (thin start -e production for instance)
This is a complicated question, but the best place to start learning about the differences would be to look at the specific environment.rb files. When rails boots up it starts with the environment file that matches the called environment, ie if you start it in development it begins by loading your development.rb file, or if you're in production it will load the production.rb file. The differences in environments are mostly the result of these differences in the various environment config files.
Basically if a Rails 3.1 app is in production mode, then by default it is not going to be compiling assets on the fly, and a lot of caching will be going on that isn't happening in development. Also, when you get error messages they will be logged but not rendered to the user, instead the static error page from your public directory will be used.
To get more insight into this, I would suggest reading the relevant rails guides:
Rails Initialization Guide: http://guides.rubyonrails.org/initialization.html
Rails Configuration Guide: http://guides.rubyonrails.org/configuring.html
There are two contexts you can use the word "production" here. One of them is running the server in production mode. You can do this locally by,
RAILS_ENV=production ./script/server
The configuration for this is picked up from config/environments/production.rb. Try comparing this file with config/environments/development.rb. There are only subtle differences like caching classes. Development mode makes it easier so that it will respond to any changes you make instantly. Plus there are two different databases (by default) will be used namely yourproject_development and yourproject_production if you choose to run your server in either of these modes.
On the other hand, rails deployment to a production box is something different. You will need to pick your server carefully. You may have to deal with a deployment script may be capistrano. You may also need a load balancer such as netgear. The database also may require a deep consideration like size expectation, master/slave clustering etc.,
Note: I have never used Rails 3. This answer is biased towards 2.3.x.