In some situations, it is not convenient to wait for a minion to start before accepting its key on the master. For instance, you may want the minion to bootstrap itself as soon as it comes online. You may also want to let your developers provision new development machines on the fly.
Many ways to preseed minion keys
Salt has other ways to generate and pre-accept minion keys in addition to the manual steps outlined below.
salt-cloud performs these same steps automatically when new cloud VMs are created (unless instructed not to).
salt-api exposes an HTTP call to Salt's REST API to
download the new minion keys as a tarball.
There is a general four step process to do this:
Generate the keys on the master:
root@saltmaster# salt-key --gen-keys=[key_name]
Pick a name for the key, such as the minion's id.
Add the public key to the accepted minion folder:
root@saltmaster# cp key_name.pub /etc/salt/pki/master/minions/[minion_id]
It is necessary that the public key file has the same name as your minion id. This is how Salt matches minions with their keys. Also note that the pki folder could be in a different location, depending on your OS or if specified in the master config file.
Distribute the minion keys.
There is no single method to get the keypair to your minion. The difficulty is finding a distribution method which is secure. For Amazon EC2 only, an AWS best practice is to use IAM Roles to pass credentials. (See blog post, https://aws.amazon.com/blogs/security/using-iam-roles-to-distribute-non-aws-credentials-to-your-ec2-instances/ )
Since the minion key is already accepted on the master, distributing the private key poses a potential security risk. A malicious party will have access to your entire state tree and other sensitive data if they gain access to a preseeded minion key.
Preseed the Minion with the keys
You will want to place the minion keys before starting the salt-minion daemon:
Once in place, you should be able to start salt-minion and run
state.apply or any other salt commands that require master authentication.