# Lab 10: Assigning Roles
In this lab we are going to start assigning roles to all nodes to categorize them by the role that they play in our infrastructure
and to start managing the run lists for each category/class collectively.

## Creating Roles




# Roles

- To create a roles in chef DSL we need to create a folder named `roles` inside the repo directory `(myapp/roles)`.
- A sample role file consist of the following,
  - Name
  - Description
  - Run_list
  - Attributes

- A sample role file is as follows `roles/sample.rb`

```ruby
name "starter"
description "An example Chef role"
run_list "recipe[starter]"
override_attributes({
  "starter_name" => "starter",
})
```

## Defining Roles

- Now create a roles for application and load_balancer.
  - sysfoo/roles/app.rb
  - sysfoo/roles/lb.rb

- Add the following content to app.rb

File: sysfoo/roles/app.rb

```console
name "app"
description "Tomcat Application Servers"
run_list "recipe[base]", "recipe[tomcat]", "recipe[chef-client]", "recipe[sysfoo::deploy]"
default_attributes({
  "chef_client" => { "interval"  =>  120,
                     "splay" => 30
                   }
})
```

- Add the following content to lb.rb

```ruby
name "lb"
description "HAProxy Load Balancers"
run_list "recipe[base]", "recipe[myhaproxy]", "recipe[chef-client]"
default_attributes({
  "chef_client" => { "interval"  =>  60,
                     "splay" => 20
                   }
})

```

## Uploading Roles to the Server

- From the `myapp` directory using knife command upload the roles from file **app.rb** and **lb.rb**

```console
knife role from file app.rb lb.rb
```

## Applying Roles to  the Nodes (run_list)

- Now replace the existing run_list of nodes with roles.
- Add run_list to node1

```console
knife node run_list set app1 "role[app]"
```

- Add run_list to node2

```console
knife node run_list set app2 "role[app]"
```

- Add run_list to node4

```console
knife node run_list set lb "role[lb]"
```

## Run chef-client on all nodes

- Now we need to run `chef-client` on all nodes.
- We can do this by passing a `sudo chef-client` command to all nodes using knife as follows

```console
knife ssh "*:*" -x devops -a ipaddress "sudo chef-client"
```

- Verify the changes using `ps aux | grep chef-client` on all nodes to find the time interval.

```console
knife ssh "*:*" -x devops -a ipaddress "ps aux | grep chef-client"
```