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Knife preflight shows details about all the nodes which uses a certain cookbook before uploading it to Chef server.
Getting Started
In order to get started, we need to have knife-preflight gem installed.
Step 1 − Define the path in the gem file.
vipin@laptop:~/chef-repo $ subl Gemfile source ''https://rubygems.org'' gem ''knife-preflight''
Step 2 − Run bundler to install knife-preflight gem.
vipin@laptop:~/chef-repo $ bundle install Fetching gem metadata from https://rubygems.org/ ...TRUNCATED OUTPUT... Installing knife-preflight (0.1.6)
Working Method
Run knife-preflight on the given cookbook.
We can run the preflight command to find out which nodes and roles have the given cookbook in their expanded run lists.
vipin@laptop:~/chef-repo $ knife preflight ntp Searching for nodes containing ntp OR ntp::default in their expanded run_list... 2 Nodes found www-staging.example.com cms-staging.example.com Searching for roles containing ntp OR ntp::default in their expanded run_list... 3 Roles found your_cms_role your_www_role your_app_role Found 6 nodes and 3 roles using the specified search criteria
There are multiple ways for a cookbook to get executed on the node.
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You can assign the cookbook directly to a node by adding it to the node”s run list.
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You can add a cookbook to the role and add the role to the node”s run list.
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You can add the role to the run list of another role and add that other role to the node”s run list.
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A cookbook can be a dependency of another used cookbook.
No matter how a cookbook ends up in a node”s run list, the knife preflight command will catch it as Chef stores all expanded lists of roles and recipes in node attributes. The knife preflight command issues a search for exactly those node attributes.
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