Chef - create template with dynamic variable?

Question

I'm having a bit of a challenge on a Chef recipe. I'm new to Chef, so please bear with me. Step 1: My chef recipe installs Ruby Passenger, then compiles the Passenger nginx module along with Nginx. ``` # Install passenger and nginx module bash "Install Passenger" do code <<-EOF source /usr/local/rvm/scripts/rvm gem install passenger EOF user "root" not_if { `gem list`.lines.grep(/^passenger $.*$/).count > 0 } end # Install passenger # Note that we have to explicitly include the RVM script otherwise it won't setup the environment correctly bash "Install passenger nginx module and nginx from source" do code <<-EOF source /usr/local/rvm/scripts/rvm passenger-install-nginx-module --auto --prefix=/opt/nginx --auto-download EOF user "root" not_if { File.directory? "/opt/nginx" } end ``` Step 2: After that, I create the nginx config file using a template. This configuration requires the location of Passenger, which is dependent on step 1 completing. ``` template "/opt/nginx/conf/nginx.conf…

Accepted Answer

A cleaner and recommended way is to use Lazy Attribute Evaluation.

```
template "/opt/nginx/conf/nginx.conf" do
  source "nginx.conf.erb"
  action :create
  variables lazy {
    { 
      deploy_user: deploy_user,
      passenger_root: `bash -c "source /usr/local/rvm/scripts/rvm; passenger-config --root"`.strip,
      passenger_ruby: `bash -c "source /usr/local/rvm/scripts/rvm; which ruby"`.strip,
      passenger: node[:passenger]
    }
  }
end
```

Also, I'd suggest using `strip` instead of `chomp` [thanks Draco].

Chef - create template with dynamic variable?

Solution

Problem