Most infrastructures are made up of groups of machines, each machine in the group performing a role similar to others. Those groups of machines work in concert with each other to create an application stack.
To effectively manage those groups of machines, an administrator needs to be able to create roles for those groups. For example, a group of machines that serve front-end web traffic might have roles which indicate that those machines should all have the Apache webserver package installed and that the Apache service should always be running.
In Salt, the file which contains a mapping between groups of machines on a
network and the configuration roles that should be applied to them is
Top files are named
top.sls by default and they are so-named because they
always exist in the "top" of a directory hierarchy that contains state files.
That directory hierarchy is called a
Top files have three components:
Environment: A state tree directory containing a set of state files to configure systems.
Target: A grouping of machines which will have a set of states applied to them.
State files: A list of state files to apply to a target. Each state file describes one or more states to be configured and enforced on the targeted machines.
The relationship between these three components is nested as follows:
Environments contain targets
Targets contain states
Putting these concepts together, we can describe a scenario in which all
minions with an ID that begins with
web have an
apache state applied
base: # Apply SLS files from the directory root for the 'base' environment
'web*': # All minions with a minion_id that begins with 'web'
- apache # Apply the state file named 'apache.sls'
Environments are directory hierarchies which contain a top file and a set of state files.
Environments can be used in many ways, however there is no requirement that
they be used at all. In fact, the most common way to deploy Salt is with
a single environment, called
base. It is recommended that users only
create multiple environments if they have a use case which specifically
calls for multiple versions of state trees.
Each environment is defined inside a salt master configuration variable
In the most common single-environment setup, only the
base environment is
file_roots along with only one directory path for
the state tree.
In the above example, the top file will only have a single environment to pull from.
Next is a simple single-environment top file placed in
illustrating that for the environment called
base, all minions will have the
state files named
edit.sls applied to them.
file_roots configuration from above, Salt will look in the
/srv/salt directory for
In some cases, teams may wish to create versioned state trees which can be used to test Salt configurations in isolated sets of systems such as a staging environment before deploying states into production.
For this case, multiple environments can be used to accomplish this task.
To create multiple environments, the
file_roots option can be
In the above, we declare three environments:
Each environment has a single directory assigned to it.
Our top file references the environments:
As seen above, the top file now declares the three environments and for each,
target expressions are defined to map minions to state files. For example, all
minions which have an ID beginning with the string
webserver will have the
webserver state from the requested environment assigned to it.
In this manner, a proposed change to a state could first be made in a state
/srv/salt/dev and then be applied to development webservers before
moving the state into QA by copying the state file into
The top file is used to assign a minion to an environment unless overridden
using the methods described below. The environment in the top file must match
valid fileserver environment (a.k.a.
saltenv) in order for any states to be
applied to that minion. When using the default fileserver backend, environments
are defined in
The states that will be applied to a minion in a given environment can be
viewed using the
Minions may be pinned to a particular environment by setting the
environment value in the minion configuration file. In doing so,
a minion will only request files from the environment to which it is assigned.
The environment may also be dynamically selected at runtime by passing it to
salt-ssh command. This is most commonly done
with functions in the
state module by using the
saltenv argument. For
example, to run a
highstate on all minions, using only the top file and SLS
files in the
prod environment, run:
salt '*' state.highstate
Not all functions accept
saltenv as an argument, see the documentation
for an individual function documentation to verify.
If you assign only one SLS to a system, as in this example, a shorthand is also available:
In the examples above, notice that all of the target expressions are globs. The default match type in top files (since version 2014.7.0) is actually the compound matcher, not the glob matcher as in the CLI.
A single glob, when passed through the compound matcher, acts the same way as
matching by glob, so in most cases the two are indistinguishable. However,
there is an edge case in which a minion ID contains whitespace. While it is not
recommended to include spaces in a minion ID, Salt will not stop you from doing
so. However, since compound expressions are parsed word-by-word, if a minion ID
contains spaces it will fail to match. In this edge case, it will be necessary
to explicitly use the
- match: glob
The available match types which can be set for a target expression in the top file are:
Full minion ID or glob expression to match multiple minions (e.g.
Perl-compatible regular expression (PCRE) matching a minion ID (e.g.
Match a grain, optionally using globbing (e.g.
Match a grain using PCRE (e.g.
Comma-separated list of minions (e.g.
Pillar match, optionally using globbing (e.g.
Pillar match using PCRE (e.g.
Pillar match with no globbing or PCRE (e.g.
Subnet or IP address (e.g.
Match values kept in the minion's datastore (created using the
Complex expression combining multiple match types (see here)
Pre-defined compound expressions in the master config file (see here)
Below is a slightly more complex top file example, showing some of the above match types:
# All files will be taken from the file path specified in the base
# environment in the ``file_roots`` configuration value.
# All minions which begin with the strings 'nag1' or any minion with
# a grain set called 'role' with the value of 'monitoring' will have
# the 'server.sls' state file applied from the 'nagios/' directory.
'nag1* or G@role:monitoring':
# All minions get the following three state files applied
# All minions which have an ID that begins with the phrase
# 'salt-master' will have an SLS file applied that is named
# 'master.sls' and is in the 'salt' directory, underneath
# the root specified in the ``base`` environment in the
# configuration value for ``file_roots``.
# Minions that have an ID matching the following regular
# expression will have the state file called 'web.sls' in the
# nagios/mon directory applied. Additionally, minions matching
# the regular expression will also have the 'server.sls' file
# in the apache/ directory applied.
# Take note of the 'match' directive here, which tells Salt
# to treat the target string as a regex to be matched!
- match: pcre
# Minions that have a grain set indicating that they are running
# the Ubuntu operating system will have the state file called
# 'ubuntu.sls' in the 'repos' directory applied.
# Again take note of the 'match' directive here which tells
# Salt to match against a grain instead of a minion ID.
- match: grain
# Minions that are either RedHat or CentOS should have the 'epel.sls'
# state applied, from the 'repos/' directory.
- match: grain_pcre
# The three minions with the IDs of 'foo', 'bar' and 'baz' should
# have 'database.sls' applied.
- match: list
# Any minion for which the pillar key 'somekey' is set and has a value
# of that key matching 'abc' will have the 'xyz.sls' state applied.
- match: pillar
When a highstate is executed and an environment is
specified (either using the
environment config option or by
passing the saltenv when executing the highstate),
then that environment's top file is the only top file used to assign states to
minions, and only states from the specified environment will be run.
The remainder of this section applies to cases in which a highstate is executed without an environment specified.
With no environment specified, the minion will look for a top file in each
environment, and each top file will be processed to determine the SLS files to
run on the minions. By default, the top files from each environment will be
merged together. In configurations with many environments, such as with
GitFS where each branch and tag is treated as a
distinct environment, this may cause unexpected results as SLS files from older
tags cause defunct SLS files to be included in the highstate. In cases like
this, it can be helpful to set
same to force each environment to use its own top file.
Another option would be to set
state_top_saltenv to a specific
environment, to ensure that any top files in other environments are
With GitFS, it can also be helpful to simply manage
each environment's top file separately, and/or manually specify the environment
when executing the highstate to avoid any complicated merging scenarios.
also be used to hide unneeded branches and tags from GitFS to reduce the number
of top files in play.
When using multiple environments, it is not necessary to create a top file for
each environment. The easiest-to-maintain approach is to use a single top file
placed in the
base environment. This is often infeasible with GitFS though, since branching/tagging can easily result in extra
top files. However, when only the default (
roots) fileserver backend is
used, a single top file in the
base environment is the most common way of
configuring a highstate.
The following minion configuration options affect how top files are compiled when no environment is specified, it is recommended to follow the below four links to learn more about how these options work:
For the scenarios below, assume the following configuration:
For the purposes of these examples, there is no top file in the
dev Environment Specified¶
In this scenario, the highstate was either invoked
saltenv=dev or the minion has
environment: dev set in the minion
config file. The result will be that only the
dev2 SLS from the dev
environment will be part of the highstate, and it
will be applied to minion2, while minion1 will have no states applied to it.
base environment were specified, the result would be that only the
base1 SLS from the
base environment would be part of the
highstate, and it would be applied to all minions.
qa environment were specified, the highstate would exit with an error.
top_file_merging_strategy is "merge"¶
In this scenario, assuming that the
base environment's top file was
evaluated first, the
qa1 states would be applied
to all minions. If, for instance, the
qa environment is not defined in
/srv/salt/base/top.sls, then because there is no top file for the
environment, no states from the
qa environment would be applied.
top_file_merging_strategy is "same"¶
Changed in version 2016.11.0: In prior versions, "same" did not quite work as described below (see here). This has now been corrected. It was decided that changing something like top file handling in a point release had the potential to unexpectedly impact users' top files too much, and it would be better to make this correction in a feature release.
In this scenario,
base1 from the
base environment is applied to all
dev2 from the
dev environment is applied to
default_top is unset (or set to
base, which happens to be
the default), then
qa1 from the
qa environment will be applied to all
default_top were set to
dev, then both
qa2 from the
qa environment would be applied to all minions.
top_file_merging_strategy is "merge_all"¶
New in version 2016.11.0.
In this scenario, all configured states in all top files are applied. From the
base1 would be applied to all minions, with
being applied only to
minion1. From the
be applied to all minions, with
dev2 being applied only to
Finally, from the
qa environment, both the
qa2 states will
be applied to all minions. Note that the
qa1 states would not be applied
twice, even though
qa1 appears twice.