The Salt file server is a high performance file server written in ZeroMQ. It manages large files quickly and with little overhead, and has been optimized to handle small files in an extremely efficient manner.
The Salt file server is an environment aware file server. This means that files can be allocated within many root directories and accessed by specifying both the file path and the environment to search. The individual environments can span across multiple directory roots to create overlays and to allow for files to be organized in many flexible ways.
The file server will restart periodically. The reason for this is to prevent any
files erver backends which may not properly handle resources from endlessly
consuming memory. A notable example of this is using a git backend with the
pygit2 library. How often the file server restarts can be controlled with the
fileserver_interval in your master's config file.
The Salt file server defaults to the mandatory
base environment. This
environment MUST be defined and is used to download files when no
environment is specified.
Environments allow for files and sls data to be logically separated, but environments are not isolated from each other. This allows for logical isolation of environments by the engineer using Salt, but also allows for information to be used in multiple environments.
environment setting is a list of directories to publish files from.
These directories are searched in order to find the specified file and the
first file found is returned.
This means that directory data is prioritized based on the order in which they
are listed. In the case of this
file_roots: base: - /srv/salt/base - /srv/salt/failover
If a file's URI is
salt://httpd/httpd.conf, it will first search for the
/srv/salt/base/httpd/httpd.conf. If the file is found there it
will be returned. If the file is not found there, then
/srv/salt/failover/httpd/httpd.conf will be used for the source.
This allows for directories to be overlaid and prioritized based on the order they are defined in the configuration.
It is also possible to have
file_roots which supports multiple
file_roots: base: - /srv/salt/base dev: - /srv/salt/dev - /srv/salt/base prod: - /srv/salt/prod - /srv/salt/base
This example ensures that each environment will check the associated environment directory for files first. If a file is not found in the appropriate directory, the system will default to using the base directory.
New in version 0.9.8.
The file server can be rerouted to run from the minion. This is primarily to
enable running Salt states without a Salt master. To use the local file server
interface, copy the file server data to the minion and set the file_roots
option on the minion to point to the directories copied from the master.
Once the minion
file_roots option has been set, change the
option to local to make sure that the local file server interface is used.