cheat sheets.

This is a copy of Chris Turners deprec2 howto (found here
http://crackthenut.cracklabs.com/deprec2-your-slice/).  I'm adding it here
because his site is down at the moment and I almost cried myself to sleep at the
thought of losing it (thank you google cache)

------------------------------

This is a summary of how we build our servers and deploy our Rails apps from
Ubuntu with the the current pre-release version of deprec2 + capistrano2.

We use Slicehost to host our Rails apps (highly recommended) and we use deprec +
capistrano to build our slices and deploy our apps. Mike Bailey has been hard at
work on deprec2, which builds on capistrano2 by Jamis Buck. Thank you to Mike
and Jamis for making these great tools that make life easier.

The machine I was deploying from here (my “development” machine) is an
Ubuntu Dapper slice with Ruby 1.8.6 and rubygems 1.0.1.

The target machine here was a Slicehost slice with Ubuntu Gutsy.

This will build the slice with Ruby 1.8.6 and latest rails (2.0.2 as of this
writing) For serving up your app it installs mongrel+nginx (not apache - though
it can easily be modified to use it)

We use another remote machine to hold our source repositories and access those
via the svn+ssh protocol. That is reflected in these instructions.

Step 1 gets your development machine set up properly and is a one-time deal. You
won’t have to repeat it for each new slice you build/deploy to.

Step 2 installs everything you’ll need on your slice and deploys your app

I wanted to get this posted sooner rather than later - it may be a bit terse -
let me know if anything is confusing or inaccurate. I’ll TRY to keep these
instruction updated as deprec2 moves into full release and other things change.
Step 1 - Set Up The Machine You Are Deploying From (running Ubuntu in this case)

This will make sure your development machine is set up the right way so that
building your slice goes smoothly. You won’t have to repeat this when you
build/deploy to future slices.
1.1. Download the pre-release deprec2 gem

Deprec 2.0 isn’t quite released yet, but there is a pre-release gem available.
As of this writing it is at version 1.99-13. You can find it at deprec.org.

The URL is almost guaranteed to change, but I’ve been grabbing the gem by:

wget
http://www.deprec.org/attachment/wiki/WikiStart/deprec-1.99.13.gem?format=raw -O
deprec-1.99.13.gem

1.2. Install Deprec

sudo gem install deprec-1.99.13.gem

Make sure you run this command from the same directory where you downloaded the
deprec gem to.
This will also install the latest version of capistrano, should you not already
have it.
1.3. Install fastthread

sudo gem install fastthread

Fastthread is necessary if you are using Ruby 1.8.6 to avoid possible deadlocks
when using capistrano (or so I hear)
1.4. Generate keys

ssh-keygen -t rsa

Accept the default name/location.

Enter a passphrase if you wish.

On my machine this creates my keys in /home/username/.ssh
1.5. Setup a directory we can use for holding slice config files

This directory is not specific to any one rails project and once we set it up we
can use
it in the future to do some of the initial setup for other slices we may build.

From within /home/username:

mkdir -p config_slices/config

1.6. Create some files for Deprec/Capistrano

Change to your config_slices directory and:

depify .

This creates:
~/.caprc
~/config_slices/Capfile
~/config_slices/config/deploy.rb

1.7. Edit your .caprc

Open up ~/.caprc with a text editor

Uncomment and update this line to point at the appropriate directory

ssh_options[:keys] = %w(/path/to/your_home_dir/.ssh/id_rsa)

like this on my machine:

ssh_options[:keys] = %w(/home/username/.ssh/id_rsa)

and uncomment these lines:

ssh_options[:forward_agent] = ...
ssh_options[:paranoid] = ...

1.8. Generate some config files locally that will be pushed out to your slice in
a future step

Make sure you are still in config_slices directory

cap deprec:ssh:config_gen

This step generates configuration files which will be used to configure the ssh
client and server on the slice.
It also makes a directory to hold public keys for you and other users so deprec
can find your keys and copy those out to the slice for you.
1.9. (optional) Make some changes to the sshd_config before you send it to the
slice

This step changes a couple settings in the the file that will be used to
configure the slice’s ssh server.
It will be more secure if you don’t make either of these changes, but there is
a chance you might find them to be useful.

Edit ~/config_slices/config/ssh/etc/ssh/sshd_config

If you still want to be able to ssh into your slice with a password (not only
keys), change the line from

PasswordAuthentication no

to

PasswordAuthentication yes

If you still want to be able to ssh into your slice as root, change the line
from

PermitRootLogin no

to

PermitRootLogin yes

1.10. Make some changes to the ssh_config before you send it to the slice

This step changes a couple settings in the the file that will be used to
configure the slice’s ssh client.
This prevents the slice from getting a host key error when it uses ssh to check
out your code from the svn repo.

Edit ~/config_slices/config/ssh/etc/ssh/ssh_config

Change:

#StrictHostKeyChecking ask

to

StrictHostKeyChecking no

1.11. Copy your public key to a place where deprec can find it

cp ~/.ssh/id_rsa.pub ~/config_slices/config/ssh/authorized_keys/deploy_user

Note: this copies and renames the file from id_rsa.pub to deploy_user

You can put whatever you want for deploy_user - this will be the username we
create on the slice later. I just use my last name. deprec makes it easy to
add/manage additional users on the slice in the future - no need to have a
single, dedicated “deploy” user.
1.12. Copy your public key out to your svn machine

PUT SOMETHING HERE

Step 2 - Set up your slice and deploy your app

Now that our development machine is set up we can move on to dealing with our
slice.
2.1. Create a new slice or rebuild one from SliceManager

Note your slice’s IP address and new root password.
2.2. Change the root password on the slice

From within config_slices directory:

cap deprec:users:passwd USER=root HOSTS=your.slice.ip.address

   1. You will be prompted for which user to change the password for - default
   is root, which is what we want - so just hit enter
   2. You will be prompted for root’s new password - type one in
   3. You will be prompted for the slice’s current root password - enter the
   password slicehost emailed you

Your slice’s root password has been changed.
2.3. Create a new user on the slice to do your deployment with

From within config_slices directory:

cap deprec:users:add USER=root HOSTS=your.slice.ip.address

   1. You will be prompted for a new username - enter whatever you used for
   deploy_user in step 1.11
   2. You will be asked if this should be an admin account -> enter yes
   3. It should tell you it has found the key you copied above (if not you named
   the key wrong or did not copy it to the correct place in 1.11) and ask if you
   want to copy it out to the slice - default is yes - so hit enter
   4. You will be prompted for a new password for deploy_user -> enter one
   5. You will be prompted for a password - enter your slice’s new root
   password from previous step

Your deploy_user has now been created on the slice and that users public key has
been copied over.
2.4. (optional) Make sure your keys work and some stuff about ssh-agent

At this point your user has been created on the slice and you should be able to
ssh into the
slice from your development machine.

If you want to make sure your keys are working properly:

PLACEHOLDER:

-test ssh into your slice with no password

-instruction for running ssh-agent to eliminate passphrases and make sure key
can get forwarded to svn if applicable

-also test you can also ssh into your svn (if you use svn+ssh) - if not then add
public key to authorized_keys on svn machine
2.5. Copy the ssh/sshd configs over to the slice

From within config_slices directory:

cap deprec:ssh:config USER=deploy_user HOSTS=my.slice.ip.address

This configures the ssh client and server on the slice according to the config
files we generated/edited in Step 1.
2.6. Setup your deploy.rb

cd my_rails_project
depify .

Edit my_rails_project/config/deploy.rb:

If you do not keep database.yml under source control add this line at the top
(after require ‘deprec’):

set :database_yml_in_scm, false

This will make sure that database.yml is symlinked from the shared/config dir
(we’ll create that file later)
If you keep database.yml in source control you should not put this line in.

Now change the following lines to match your specifics:

set :user, "deploy_user"
set :application, "my_rails_project"
set :repository, 
"svn+ssh://my_svn_useruser@my_svn/path_to/my_rails_project/trunk"  #or whatever
set :domain, "my.slice.ip.address" #or domain name if you have that setup
role :app, domain
role :web, domain
role :db,  domain, :primary => true

2.7. Install ruby/rails/mysql/mongrel/nginx and everything else you need on the
slice

From within my_rails_project directory:

cap deprec:rails:install_rails_stack

And you thought that would be hard…
This step saves you a LOT of work (thank you Mike Bailey)
It takes a little while, ~10 min when I ran it.
2.8. Run the initial deploy to get things configured

From within my_rails_project directory:

cap deploy:setup
cap deploy

This sets up your application on the slice and does an initial check out from
your svn.
2.9. Create database.yml on the slice if you don’t keep it in source control

Skip this step if database.yml is under source control.

Add the following to my_rails_project/config/deploy.rb inside the
namespace:deploy block

db_params = {
  "adapter"=>"mysql",
  "database"=>"#{application}_#{rails_env}",
  "username"=>"root",
  "password"=>"",
  "host"=>"localhost",
  "socket"=>""
}

db_params.each do |param, default_val|
  set "db_#{param}".to_sym,
    lambda { Capistrano::CLI.ui.ask "Enter database #{param}" do |q|
    q.default=default_val end}
end

task :my_generate_database_yml, :roles => :app do
  database_configuration = "#{rails_env}:\n"
  db_params.each do |param, default_val|
    val=self.send("db_#{param}")
    database_configuration<<"  #{param}: #{val}\n"
  end
  run "mkdir -p #{deploy_to}/#{shared_dir}/config"
  put database_configuration, "#{deploy_to}/#{shared_dir}/config/database.yml"
end

Now run this task to create database.yml

cap deploy:my_generate_database_yml

Follow the prompts - this makes database.yml - the defaults are likely ok (just
hit enter) at all of the prompts.

2.10. Create the database and apply migrations

Still from within my_rails_project directory:

cap deprec:db:create
cap deprec:db:migrate

This creates your database and applies your migrations.

2.11. Restart mongrel+nginx

Still from within my_rails_project directory:

cap deprec:mongrel:restart
cap deprec:nginx:restart

Now you should be able to point your browser at your slice and see your app
running. Congrats!