MinionFS Backend Walkthrough¶

Propagating Files¶

Sometimes, one might need to propagate files that are generated on a minion. Salt already has a feature to send files from a minion to the master.

Enabling File Propagation¶

To enable propagation, the file_recv option needs to be set to True.

file_recv: True

These changes require a restart of the master, then new requests for the salt://minion-id/ protocol will send files that are pushed by cp.push from minion-id to the master.

salt 'minion-id' cp.push /path/to/the/file

This command will store the file, including its full path, under cachedir /master/minions/minion-id/files. With the default cachedir the example file above would be stored as /var/cache/salt/master/minions/minion-id/files/path/to/the/file.

MinionFS Backend¶

Since it is not a good idea to expose the whole cachedir, MinionFS should be used to send these files to other minions.

Simple Configuration¶

To use the minionfs backend only two configuration changes are required on the master. The fileserver_backend option needs to contain a value of minion and file_recv needs to be set to true:

fileserver_backend:
  - roots
  - minion

file_recv: True

These changes require a restart of the master, then new requests for the salt://minion-id/ protocol will send files that are pushed by cp.push from minion-id to the master.

Commandline Example¶

Lets assume that we are going to generate SSH keys on a minion called minion-source and put the public part in ~/.ssh/authorized_keys of root user of a minion called minion-destination.

First, lets make sure that /root/.ssh exists and has the right permissions:

[root@salt-master file]# salt '*' file.mkdir dir_path=/root/.ssh user=root group=root mode=700
minion-source:
    None
minion-destination:
    None

We create an RSA key pair without a passphrase [*]:

[root@salt-master file]# salt 'minion-source' cmd.run 'ssh-keygen -N "" -f /root/.ssh/id_rsa'
minion-source:
    Generating public/private rsa key pair.
    Your identification has been saved in /root/.ssh/id_rsa.
    Your public key has been saved in /root/.ssh/id_rsa.pub.
    The key fingerprint is:
    9b:cd:1c:b9:c2:93:8e:ad:a3:52:a0:8b:0a:cc:d4:9b root@minion-source
    The key's randomart image is:
    +--[ RSA 2048]----+
    |                 |
    |                 |
    |                 |
    |  o        .     |
    | o o    S o      |
    |=   +  . B o     |
    |o+ E    B =      |
    |+ .   .+ o       |
    |o  ...ooo        |
    +-----------------+

and we send the public part to the master to be available to all minions:

[root@salt-master file]# salt 'minion-source' cp.push /root/.ssh/id_rsa.pub
minion-source:
    True

now it can be seen by everyone:

[root@salt-master file]# salt 'minion-destination' cp.list_master_dirs
minion-destination:
    - .
    - etc
    - minion-source/root
    - minion-source/root/.ssh

Lets copy that as the only authorized key to minion-destination:

[root@salt-master file]# salt 'minion-destination' cp.get_file salt://minion-source/root/.ssh/id_rsa.pub /root/.ssh/authorized_keys
minion-destination:
    /root/.ssh/authorized_keys

Or we can use a more elegant and salty way to add an SSH key:

[root@salt-master file]# salt 'minion-destination' ssh.set_auth_key_from_file user=root source=salt://minion-source/root/.ssh/id_rsa.pub
minion-destination:
    new