Automated Deployment Messages

Friday, October 5, 2012

Make deployment visible with Capistrano, Autotagger, Git and Sendgrid

There comes a time in every project when the deployment process comes of age, and that development arrives with its own set of Capistrano recipes and Rake tasks. The project I’m on hit that point recently, and one of the neat outcomes of its nascent puberty was a simple Capistrano recipe to send a git changelog to our project mailing list.

Here’s what this looks like:

$ cap staging deploy
... stuff happens here ...
  * executing `sendgrid:notify'
Changelog:
04fc6dd adding capistrano deployment messages

To use this in your Rails project, the first thing you need is a sendgrid account. If you’re budget-minded, you can always use the credentials your Heroku app is using.

$ heroku create
Creating heroku-wackiness-90210... done, stack is cedar
http://heroku-wackiness-90210.herokuapp.com/ | git@heroku.com:heroku-wackiness-90210.git
Git remote heroku added
$ heroku addons:add sendgrid:starter
Adding sendgrid:starter on heroku-wackiness-90210... done, v2 (free)
Use `heroku addons:docs sendgrid:starter` to view documentation.
$ heroku config -s
SENDGRID_PASSWORD=s3kr17
SENDGRID_USERNAME=yodawg@heroku.com

This process uses Capistrano and Autotagger. For information on setting up Capistrano, their wiki is an excellent starting point. For Autotagger setup with Capistrano, Jeff Dean’s auto_tagger repository is the canonical source of information.

After you’re up and running with Capistrano and Autotagger, you need to add the following file under lib/recipes/sendgrid_notifier.rb:

require 'mail'

set :sendgrid_user, "whatever"
set :sendgrid_password, "secret"
set :sendgrid_domain, "pivotallabs.com"

set :sender, "Now Hiring <jobs@pivotallabs.com>"
set :recipient, "Steve Squivot <you@square.com>"

namespace :sendgrid do
  task :notify do
    sendgrid = {
      :address   => "smtp.sendgrid.net",
      :port      => 587,
      :domain    => sendgrid_domain,
      :user_name => sendgrid_user,
      :password  => sendgrid_password,
      :authentication => 'plain',
      :enable_starttls_auto => true
    }

    auto_tagger = AutoTagger::CapistranoHelper.new(
      :stage => rails_env,
      :stages => auto_tagger_stages).auto_tagger
    previous_sha = auto_tagger.refs_for_stage(stage).last.sha
    current_sha = auto_tagger.repo.latest_commit_sha

    mail = Mail.new(from: recipient, to: sender)
    mail.delivery_method :smtp, sendgrid
    mail.subject = "[#{stage}] New Deployment!"
    mail.body = `git log --oneline #{previous_sha}..#{current_sha}`
    mail.deliver!
  end
end

Then, let’s add a line to include this recipe in our Capfile:

require File.expand_path("../lib/recipes/sendgrid_notifier.rb", __FILE__)

Finally, let’s try it out:

$ cap ci sendgrid:notify
  * executing `sendgrid:notify'
Changelog:
04fc6dd add a recruiter message to send off to Square

Alright! The email’s on its way. If you need to call this in your custom deployment step, it’s as easy as sticking sendgrid.notify into your Capfile.

Happy deploying!

Verifying hosts are active in the load balancer pool

Pivotal Labs

Wednesday, January 11, 2012

Most load balancers have a heart beat monitor, that allows the load balancer to decide whether or not to send traffic to a given host.

For example:

http://server1.host.com/check.txt

If the load balancer gets a 200, it will send traffic to server1, if it gets a 404 or a timeout, it will not.

Today we were trying to figure out how to find what servers were up and running in the load balancer pool.

Here’s the capistrano task we came up with:

desc "Curls the check.txt file to see if the host is in the load balancer"
  task :check_load_balancer do
    roles[:web].map(&:host).each do |hostname|
      value = %x{/usr/bin/curl -fs 'http://#{hostname}/check.txt'}
    puts "Curling http://#{hostname}/check.txt: #{value}"
  end
end

This gives you output like the following:

$ cap production deploy:check_load_balancer
  * executing `production'
  * executing `deploy:check_load_balancer'
Curling http://server2.dc1.domain.com/check.txt:
Curling http://server3.dc1.domain.com/check.txt: OK
Curling http://server4.dc1.domain.com/check.txt: OK
Curling http://server5.dc1.domain.com/check.txt:
Curling http://server6.dc1.domain.com/check.txt: OK
Curling http://server7.dc1.domain.com/check.txt: OK
Curling http://server8.dc1.domain.com/check.txt: OK
$

Now we can easily see there are issues with server 2 and 5.

Standup 9/10/2009: "All Alias, All The Time"

Pivotal Labs

Thursday, September 10, 2009

Interesting Things

One team reported that Capistrano can’t deal with host aliases in .ssh/config. Others use host aliases with capistrano without trouble. The problem could be related to multiple host aliases. All this led to the statement:
If you are working with EY, you should go all alias, all the time.
Problems with JsUnit and Firefox 3.5. From Adam:
If you’re planning to use JsUnit, or you already use JsUnit
and you plan to upgrade your Firefox to version 3.5, you
may run into this problem. Apparently the security settings
in Firefox were updated in 3.5 to restrict file access in a way
that stymies JsUnit. If you don’t fix this JsUnit will fail to open
test files, and will simply hang on tests runs, with no error
output. To fix it:
- type ‘about:config’ in the Firefox URL bar
- Filter by ‘security.fileuri.strict_origin_policy’
- Set this to false

Standup 06/25/2009: return vs. next vs. break vs. yslow vs. cap

Joe Moore

Thursday, June 25, 2009

Interesting Things

You can never return: … except when you can. From a block, that is. Returning from a block rarely works:

result = ['one', 'two'].each do |x|
 return x
end
=> LocalJumpError: unexpected return

But, you can pass next and break arguments, which will allow you to assign return values from the block:

result = ['one', 'two'].each do |x|
  break(x)
end
=> "one"


result = ['one', 'two'].each do |x|
  next(x)
end
=> ["one", "two"]

You can return from a lambda, though.

Check out Google Page Speed, which is like Yahoo’s YSlow, only “better.”
Page Speed is an open-source Firefox/Firebug Add-on. Webmasters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them.
Like chef? Love capistrano? Check out chef-deploy, which “… Uses the same directory layout as capistrano and steals the git remote cached deploy strategy from cap and adapts it to work without cap and under chef.”
SFTUG FTW! Another successful SF Tracker User Group Meetup on 06/24. Watch for future events on the Meetup site.