Friday, April 17, 2015

Validatorless Bootstraps [feedly]

Validatorless Bootstraps
// Chef Blog

Starting with the Chef 12.2.0 Client there is no longer any need to use the validation key to provision new chef nodes with knife. Furthermore, all that needs to be done to take advantage of this feature is to delete your validation keys and optionally remove the validator configuration from your knife.rb file.

Instead of shipping a validation key up to the newly provisioned node and having the node use the validation key to authorize itself to provision a new client and node, the knife bootstrap command will use the user's key to create a client key for the node, use the client key to create a node object, and then ship the client key up to the node.

Configuration Details

Starting with Chef 12.2.0 existing Users will begin seeing a new banner on new knife bootstraps:

Doing old-style registration with the validation key at /home/lamont/.chef/myorg-validator.pem...  Delete your validation key in order to use your user credentials instead  

In order to use the new behavior it is as simple as deleting the validator key:

rm -f /home/lamont/.chef/myorg-validator.pem  

The existing validation_client_name and validation_key parameters in the knife.rb file can also be deleted. Note that the default value of the validation_key is "/etc/chef/validation.pem" and if that file happens to exist on the workstation or server that it will attempt to be used after removing the validation_key setting. That file should either also be deleted, or else the validation_key should be set to something like "/nonexist" to disable it.

Provisioning Details

The new output of knife bootstrap when not using a validation key will look similar to:

desktop% knife bootstrap -N \     -E dev -r 'role[base] -j '{ "foo": "bar" }' \     --ssh-user vagrant --sudo  Node exists, overwrite it? (Y/N)  Client exists, overwrite it? (Y/N)   Creating new client for  Creating new node for  Connecting to Starting first Chef Client run...  [....etc...]  

What you can see here is that if the node and client already exist that knife bootstrap will prompt to overwrite them. The '-y' command line flag can be used to skip the prompts and answer 'y' to both questions. The new client is created first and the new node is then created with the client key.

Behind the scenes the '-r' and '-E' and '-j' flags to knife bootstrap are already applied to the new node which gets created — so the object in the database will have its run_list, environment and initial 'normal' json attributes saved. This avoids the edge condition where for some reason if the initial chef-client run fails the node is never saved and it 'forgets' its own run_list and environment. Since the node is saved with that correct data before provisioning starts on the host, the run_list will still be correct even if the initial chef-client run fails for some reason.


The validatorless bootstrap changes to Chef 12.2.0 achieve a few key things:

  • No more need for the validation key (fewer things, reduced fussiness)
  • Ability to eliminate shared access (and ultimately have better auditing around provisioning actions)
  • Eliminating the first-run failure edge conditions where a node forgets its run_list, environment or attributes
  • Gracefully handling the situation where an old Client key or Node object exist in the database


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