Chef食谱是否遵循固定步骤？现有食谱代码存疑求解答

Absolutely! Chef recipes follow a predictable two-phase execution flow that’s critical to wrap your head around when writing them:

• Compile Phase: Chef first reads all your recipe code, parses resources to build a "resource collection" (a list of all desired system changes), and runs any raw Ruby code that isn’t wrapped in a resource. This happens before any actual modifications are made to the system.
• Converge Phase: Chef works through the resource collection in order, executing each resource to make sure the system matches the desired state you’ve defined.

Feedback on Your Current Code #

Looking at your snippet, there’s a key timing issue that’s probably causing problems. Let’s break it down:

1. The directory resource: This is scheduled to run during the converge phase, meaning /opt/test/scripts won’t exist until Chef starts making changes to the system.
2. The raw Ruby download code: This runs during the compile phase—before the directory is created. So when File.write('/opt/test/scripts/pair.sh', response.body) tries to save the file, it’ll throw an error because the parent folder doesn’t exist yet.
3. The not_if condition: Your current check grep /opt/test doesn’t actually verify if the directory exists. It’s searching for the string "/opt/test" in standard input, which isn’t what you want. You should use a command that directly checks for the directory, like test -d /opt/test/scripts.

Improved Version Using Chef Resources #

Instead of raw Ruby, use Chef’s built-in resources which are designed to work seamlessly with the two-phase flow. Here’s a better approach:

# Create the directory first (runs in converge phase)
directory '/opt/test/scripts' do
  owner 'root'
  group 'root'
  mode '0755'
  action :create
  recursive true
  not_if 'test -d /opt/test/scripts'
end

# Download the file using Chef's remote_file resource (runs after directory is created)
remote_file '/opt/test/scripts/pair.sh' do
  source 'https://repo.test2.io/BwIaTHE0ohsUts74LYZMzrt/pair.sh'
  owner 'root'
  group 'root'
  mode '0755'
  action :create
end

This setup ensures:

• The directory resource guarantees the folder exists before the file is downloaded.
• remote_file handles downloading, file creation, and permissions all in one idempotent resource (it won’t re-download or reconfigure the file if it already matches the desired state).
• The not_if condition correctly checks for the directory’s existence.

Content of the question originates from Stack Exchange, question author: anish anil