厨师食谱如何检查文件是否存在

Question

I just started using Chef and I'm trying to figure out how to first check if a file exists before doing anything.

I have the file part down for my current use case, where I'm removing a login file for the production server, ex:

file '/var/www/html/login.php' do
    action :delete
end

However, I'd like the abilty to first check if the file exists, ex.

if (file_exists === true)
    file '/var/www/html/login.php' do
        action :delete
    end
end

Answer 1

As mentioned in the comments, for a deletion action, the if statement is unnecessary, as mentioned, because if chef doesn't find the file to be deleted, it will assume it was already deleted.

Otherwise, you generally want to use guard properties in the resource (available for all resources), rather than wrapping a resource in an if-then.

file '/var/www/html/login.php' do
    only_if { ::File.exist?('/var/www/html/login.php') }
    action :touch
end

And you probably also want to familiarize yourself with the Ruby File class methods .

Answer 2

The basic idea of Chef is that you state the desired state of the system, and then Chef compares that to the actual state, and makes any changes needed to bring the system into the desired state. You do not need to have an if statement to check if the file exists before deleting it; Chef itself should check if the file exists if I'm not mistaken.