Resources and Recipes

CHAPTER 3

Chef Solo Version

TOPICS

  • Resource DSL

  • Recipes

  • chef-client

  • Idempotence

  • Execute Resource 

Resources

Chef looks at your infrastructure as a collection of entities

package

file

network interface

service

cronjob

cronjob

user

directory

Resources

these entities can then be described using resources. 

Ruby DSL

( Domain specific language) 
which are written using 
resources are statements of configuration policy

Resources

Chef then translates these resources 

package

yum

apt

zypper

          into providers 
          which are platform specific procedures

DSL

user 
'devops'
do
end
action 
:create
uid
gid
home
shell
'5001'
'5001'
'/home/devops'
'/bin/bash'

type

name

properties

Finding resources

how do i know which resources to use with what actions and properties? 

RECIPES

  • recipes are files which contain collection of resources
  • written to  achieve a specific objective
  • have .rb extension 
  • resources in a recipe are always applied in serial order

user 'www-data' do
  comment 'web admin'
  uid '1004'
  gid 'www-data'
  shell '/bin/sh'
end

package 'httpd' do 
  action :install
enf


service 'httpd' do
  action [:enable, :start]
end

writing our first recipe

Group exercise

  • tree

  • git

  • ntp

Create user

  • deploy 

Install Packages

Lets create a recipe base.rb with following resource specifications

Remove user

  • dojo 

Add file /etc/motd

with content

"Property of XYZ"

  • wget

  • unzip

Start service

  • ntp

approach

Group exercise

  • Find out the chef resource required to manage the entity
  • Find out the relevant actions and properties
  • Create a recipe and apply

Writing first resource

recipe

Group exercise

file:  base.rb

 


user 'deploy' do 
  uid 5001
  home '/home/deploy'
  action :create
  password '$1$Ze1eJK3R$j5I0NRP5WxbZAaeXcfYW7/'
end

Syntax check

Group exercise


[output]

Syntax OK
/opt/chefdk/embedded/bin/ruby -c base.rb

applying recipe

chef-client
  • we are using a masterless chef mode, and applying chef recipe locally
  • chef-client comes with has introduced  -z | --local-mode option which allows it to apply recipes locally
    
  • It actually sets up a light weight, fast, in memory chef server to apply configuration locally. 

Alternate methods

chef-client
chef-apply
chef-solo

- applies single recipe

- works with only limited features

applying recipe

Group exercise

chef-solo --help
Usage: /usr/local/bin/chef-solo (options)
    -f, --[no-]fork                  Fork client
        --[no-]color                 Use colored output, defaults to enabled
    -c, --config CONFIG              The configuration file to use
    -d, --daemonize                  Daemonize the process
        --delete-entire-chef-repo    DANGEROUS: does what it says, only useful with --recipe-url
    -E, --environment ENVIRONMENT    Set the Chef Environment on the node
        --ez                         A memorial for Ezra Zygmuntowicz
        --force-formatter            Use formatter output instead of logger output
        --force-logger               Use logger output instead of formatter output
    -F, --format FORMATTER           output format to use
    -g, --group GROUP                Group to set privilege to
    -i, --interval SECONDS           Run chef-client periodically, in seconds
    -j JSON_ATTRIBS,                 Load attributes from a JSON file or URL
        --json-attributes
        --lockfile LOCKFILE          Set the lockfile location. Prevents multiple processes from converging at the same time
    -l, --log_level LEVEL            Set the log level (debug, info, warn, error, fatal)
    -L, --logfile LOGLOCATION        Set the log file location, defaults to STDOUT
        --minimal-ohai               Only run the bare minimum ohai plugins chef needs to function
    -N, --node-name NODE_NAME        The node name for this client
    -o RunlistItem,RunlistItem...,   Replace current run list with specified items
        --override-runlist
        --[no-]profile-ruby          Dump complete Ruby call graph stack of entire Chef run (expert only)
    -r, --recipe-url RECIPE_URL      Pull down a remote gzipped tarball of recipes and untar it to the cookbook cache.
        --run-lock-timeout SECONDS   Set maximum duration to wait for another client run to finish, default is indefinitely.
    -s, --splay SECONDS              The splay time for running at intervals, in seconds
    -u, --user USER                  User to set privilege to
    -v, --version                    Show chef version
    -W, --why-run                    Enable whyrun mode
    -h, --help                       Show this message

options

-W,  --why-run 
-l,  --log_level info
-c,  --config config file         to use (solo.rb)

solo.rb

Group exercise

file: /workspace/solo.rb
cookbook_path "cookbooks"
log_location  "/var/log/chef.solo.log"
log_level     :info

(dry) why run

Group exercise

chef-solo -c /workspace/solo.rb --why-run base.rb
# chef-solo -c /workspace/solo.rb --why-run base.rb                                     
Starting Chef Client, version 12.16.42                                                                             
resolving cookbooks for run list: []                                                                               
Synchronizing Cookbooks:                                                                                           
Installing Cookbook Gems:                                                                                          
Compiling Cookbooks...                                                                                             
[2017-09-11T07:53:32+00:00] WARN: Node ws.codespaces.io has an empty run list.                                     
Converging 1 resources                                                                                             
Recipe: @recipe_files::/workspace/chapter3/base.rb                                                                 
  * linux_user[deploy] action create                                                                               
    - Would create user deploy                                                                                     
[2017-09-11T07:53:32+00:00] WARN: In why-run mode, so NOT performing node save.                                    
                                                                                                                   
Running handlers:                                                                                                  
Running handlers complete                                                                                          
Chef Client finished, 1/1 resources would have been updated  

commit changes

Group exercise

chef-solo -c /workspace/solo.rb  base.rb
# chef-solo -c /workspace/solo.rb  base.rb                                              
Starting Chef Client, version 12.16.42                                                                             
resolving cookbooks for run list: []                                                                               
Synchronizing Cookbooks:                                                                                           
Installing Cookbook Gems:                                                                                          
Compiling Cookbooks...                                                                                             
[2017-09-11T07:54:44+00:00] WARN: Node ws.codespaces.io has an empty run list.                                     
Converging 1 resources                                                                                             
Recipe: @recipe_files::/workspace/chapter3/base.rb                                                                 
  * linux_user[deploy] action create                                                                               
    - create user deploy                                                                                           
                                                                                                                   
Running handlers:                                                                                                  
Running handlers complete                                                                                          
Chef Client finished, 1/1 resources updated in 02 seconds                                                          

workflow

build node

load run list

/recipes

synchronize 

cookbooks

compile

converge

phase1

phase2

convergence

  • by defining the policy, and
  • by comparing current state of the infrastructure and 
  • bring it in line with the policy by
  • taking action/not taking action
  • chef resources are idempotent (most)
Chef takes a convergent approach to configuration

apply again

Group exercise

chef-solo -c /workspace/solo.rb  base.rb                                              
Starting Chef Client, version 12.16.42                                                                             
resolving cookbooks for run list: []                                                                               
Synchronizing Cookbooks:                                                                                           
Installing Cookbook Gems:                                                                                          
Compiling Cookbooks...                                                                                             
[2017-09-11T07:56:29+00:00] WARN: Node ws.codespaces.io has an empty run list.                                     
Converging 1 resources                                                                                             
Recipe: @recipe_files::/workspace/chapter3/base.rb                                                                 
  * linux_user[deploy] action create (up to date)                                                                  
                                                                                                                   
Running handlers:                                                                                                  
Running handlers complete                                                                                          
Chef Client finished, 0/1 resources updated in 02 seconds                                                          
chef-solo -c /workspace/solo.rb  base.rb

Exercise

LAB

  • tree

  • git

  • ntp

Install Packages

Lets create a recipe base.rb with following resource specifications

Remove user

  • dojo 

Add file /etc/motd

with content

"Property of XYZ"

  • wget

  • unzip

Start service

  • ntp

guards

  • not_if
  • only_if

Execute Resource 

Guards

creates

action :nothing

Common Functionality

  • notifies
  • ​​subscribes

Execute Resource 

Notifications

action :nothing

Actions

  • not_if
  • only_if

Guards

  • :before
  • :delayed
  • :immediate, :immediately

Timers

sample code

package ['libsqlite3-dev', 'sqlite3']

execute 'download_facebooc_from_source' do
  command 'wget https://github.com/jserv/facebooc/archive/master.zip'
  cwd '/opt'
  user 'root'
  creates '/opt/master.zip'
  notifies :run, 'execute[extract_facebook_app]', :immediately
end


execute 'extract_facebook_app' do 
  command 'unzip master.zip  && touch /opt/.facebooc_compile'
  cwd '/opt'
  user 'root'
  action :nothing
end 


execute 'compile_facebooc' do 
  command 'make all && rm /opt/.facebooc_compile'
  cwd '/opt/facebooc-master'
  user 'root'
  only_if 'test -f /opt/.facebooc_compile'
  action :run
end 


execute 'run_facebooc' do 
  command 'bin/facebooc 16000 &'
  cwd '/opt/facebooc-master'
  user 'root'
  not_if 'netstat -an | grep 16000 | grep -i listen'
  action :run
end 

LAB

summary

 

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