Multi Node Cluster

In this session we going to simulate a realistic environment with multiple nodes being managed with Chef Server, similar to most of the real world implementations.

This would include 3 components,

  • Chef Workstation (Could be your personal PC/Laptop)
  • Chef Server (Hosted or On-Premises )
  • Chef Clients ('n' number of machines; could be VM, AWS EC2, etc..)

Multi-Node

Setting up Hosted Chef Server Environment

Chef server comes in two flavors * Open Source * Enterprise

Enterprise version of chef has two sub types * Hosted * On Premises

In terms of features, both on prem and hosted versions are the same. The only difference is whether you use the SaaS solution from Chef, or you want to host it in house.

For this workshop, we would be using Hosted Enterprise Chef for the following reasons,

  • Ease of setup : hosted version is a breeze to setup and you have a working chef server setup within minutes
  • Resource Optimization: On Premises version of chef server takes a lot of resources to setup and use e.g. 4GB of RAM with atleast dual core for getting a decent operational version. Thats too much in most learning lab environments. Hosted version takes zero resources to setup.

Lets learn how to setup our hosted chef account...

Creating an Account

  • Now let us create a account in chef.io to manage our own hosted chef server.
  • Once account is created, verify and login.
  • Now create a organization of your own and then download chef-starter kit.

Setting Up Workstation

  • Upload starter kit to the workspace. Its the chef-starter.zip file that you downloaded from chef server.
  • Upload the file to workspace and extract it. You should see chef-repo directory created after being extracted.
  • Change into chef-repo directory created as the outcome of above command and validate workstation by running 
knife client list

The above command will return the orgname-validator client. If it does,you have successufully validated all of following,

  • Workstation software (knife) is installed
  • You have required configurations, authentication keys/credentials to talk to Chef Server
  • Chef Server is setup and ready
  • Workstation is able to communicate with Chef Server. There are no network issues etc.
  • Workstaiton is able to authenticate with Chef Server
  • Workstation has made the API request and displays the results returned by Chef Server

Tree

Moving knife configs to workspace

  • Copy .chef directory from chef-repo to workspace.

mv /workspace/chef-repo/.chef  /workspace

Alternately you could also create a symbolic link/symlink.

From here on all knife commands work from any subdirectory of /workspace.

Bootstrapping a Managed Node

  • Now run knife client list to get the list of client associated with the hosted chef-server.
  • In our case we don't have any client as of now, so lets start adding nodes by using knife bootstrap command.
  • From Workstation we need to bootstrap client.
  • In codespaces environment we have pre-built nodes associated with the following IP.
Node Name IP Port Mapping
node1 app1 177.0.101.10 8081:8080
node2 app2 177.0.101.11 8082:8080
node3 app3 177.0.101.12 8083:8080
node4 lb 177.0.101.13 8084:8080

  • All nodes are accessible using ssh without password.

  • Lets bootstrap node1 using the following command

knife bootstrap node1 --ssh-user devops --sudo -N app1
  • Here -N is used to define the name of the node that we bootstrap.
  • --ssh-user is used to provide the name of the user in that particular node.
  • Also using --sudo to connect is to provide root previlages for running all the command.

  • app1 is bootstrapped successfully.

  • Now check for the available nodes

knife node list
  • Check for the existing status and specified runlist for node1(app1)
knife node show app1

Providing configurations to the Node

To provide configurations, you would need to upload the cookbooks to chef server and set the run list.

Before we do so, we also need to updated the path where knife would look in to find the cookbooks.

Edit /workspace/.chef/knife.rb
and update cookbook_path from

cookbook_path  ["#{current_dir}/../cookbooks"]

to

cookbook_path       ["cookbooks"]

Change into chapter6/sysfoo directory on workstation.

Upload the cookbooks that we created and tested locally earlier.

knife cookbook upload java tomcat

Defining Run List for the Node

knife node show app1
knife node run_list add app1 "recipe[tomcat]"

To apply, login to node1 and run chef-client

ssh devops@node1
sudo chef-client

Managing Chef Client as a Service

Lets now start managing chef-client and its configurations through chef cookbooks. We have a special purpose cookbook by name chef-client which allows us to do so. It will, * decide how to run chef-client, eg. cronjob, service etc. * does support various types of service managers e.g. runit, bluepill, supervisord etc. * manages configurations for chef client .eg. how frequently chef-client runs

Lets upload chef-client cookbook which is already present if you are using the code repository provides.

knife cookbook upload chef-client

Did chef-client cookbook get uploaded successfully? If not, observe the error and try to deduct the root cause.

Berkshelf

Berkshelf is a dependency manager for Chef cookbooks. With it, you can easily depend on community cookbooks and have them safely included in your workflow. You can also ensure that your CI systems reproducibly select the same cookbook versions, and can upload and bundle cookbook dependencies without needing a locally maintained copy. Berkshelf is included in the Chef Development Kit.

  • Now look into the downloaded chef-client cookbook.
  • It has berksfile where the dependent cookbook are mentioned.
  • To run berks command we need to be in the directory where berksfile is located, that is workspace/sysfoo/cookbooks/chef-client
  • Now run install and upload command.
cd cookbooks/chef-client

berks install; berks upload

cd ../..

Lets now add chef-client recipe to the runlist of node1.

knife node run_list add app1 "recipe[chef-client]"

To apply this recipe, login to node1 and run chef client as,

ssh devops@node1
sudo chef-client

Providing run list while bootstrapping

For node1, we did the following, * Bootstrapped the node * Defined run list * Logged in to the node and run chef-client

For initial node this was needed as you are learning to apply one concept at a time, and you did not have the cookbooks uploaded on the server. Now that its all ready, you could combine these operations into one by defining the run list, right at the bootstrap time.

Lets bootstrap node2 this time with tomcat and java configs

knife bootstrap node2 -x devops --sudo -N app2 -r "recipe[tomcat],recipe[chef-client]"
  • --run-list is used to specify run-list and by applying recipes to the node at the time of bootstrap.
  • Now verify by visiting host ip with port mapping of 8080 to 8081 for node1 http://ip:8081 and port mapping of 8080 to 8082 for node2 http://ip:8082, where the tomcat application is installed and service is up and running.