Basic Usage of Provisioners

While Vagrant offers multiple options for how you are able to provision your machine, there is a standard usage pattern as well as some important points common to all provisioners that are important to know.

Configuration

First, every provisioner is configured within your Vagrantfile using the config.vm.provision method call. For example, the Vagrantfile below enables shell provisioning:

Vagrant.configure("2") do |config|
  # ... other configuration

  config.vm.provision "shell", inline: "echo hello"
end

Every provisioner has a type, such as "shell", used as the first parameter to the provisioning configuration. Following that is basic key/value for configuring that specific provisioner. Instead of basic key/value, you can also use a Ruby block for a syntax that is more like variable assignment. The following is effectively the same as the prior example:

Vagrant.configure("2") do |config|
  # ... other configuration

  config.vm.provision "shell" do |s|
    s.inline = "echo hello"
  end
end

The benefit of the block-based syntax is that with more than a couple options it can greatly improve readability. Additionally, some provisioners, like the Chef provisioner, have special methods that can be called within that block to ease configuration that cannot be done with the key/value approach, or you can use this syntax to pass arguments to a shell script.

The attributes that can be set in a single-line are the attributes that are set with the = style, such as inline = "echo hello" above. If the style is instead more of a function call, such as add_recipe "foo", then this cannot be specified in a single line.

Provisioners can also be named (since 1.7.0). These names are used cosmetically for output as well as overriding provisioner settings (covered further below). An example of naming provisioners is shown below:

Vagrant.configure("2") do |config|
  # ... other configuration

  config.vm.provision "bootstrap", type: "shell" do |s|
    s.inline = "echo hello"
  end
end

Naming provisioners is simple. The first argument to config.vm.provision becomes the name, and then a type option is used to specify the provisioner type, such as type: "shell" above.

Running Provisioners

Provisioners are run in three cases: the initial vagrant up, vagrant provision, and vagrant reload --provision.

A --no-provision flag can be passed to up and reload if you do not want to run provisioners. Likewise, you can pass --provision to force provisioning.

The --provision-with flag can be used if you only want to run a specific provisioner if you have multiple provisioners specified. For example, if you have a shell and Puppet provisioner and only want to run the shell one, you can do vagrant provision --provision-with shell. The arguments to --provision-with can be the provisioner type (such as "shell") or the provisioner name (such as "bootstrap" from above).

Run Once, Always or Never

By default, provisioners are only run once, during the first vagrant up since the last vagrant destroy, unless the --provision flag is set, as noted above.

Optionally, you can configure provisioners to run on every up or reload. They will only be not run if the --no-provision flag is explicitly specified. To do this set the run option to "always", as shown below:

Vagrant.configure("2") do |config|
  config.vm.provision "shell", inline: "echo hello",
    run: "always"
end

You can also set run: to "never" if you have an optional provisioner that you want to mention to the user in a "post up message" or that requires some other configuration before it is possible, then call this with vagrant provision --provision-with bootstrap.

If you are using the block format, you must specify it outside of the block, as shown below:

Vagrant.configure("2") do |config|
  config.vm.provision "bootstrap", type: "shell", run: "never" do |s|
    s.inline = "echo hello"
  end
end

Multiple Provisioners

Multiple config.vm.provision methods can be used to define multiple provisioners. These provisioners will be run in the order they're defined. This is useful for a variety of reasons, but most commonly it is used so that a shell script can bootstrap some of the system so that another provisioner can take over later.

If you define provisioners at multiple "scope" levels (such as globally in the configuration block, then in a multi-machine definition, then maybe in a provider-specific override), then the outer scopes will always run before any inner scopes. For example, in the Vagrantfile below:

Vagrant.configure("2") do |config|
  config.vm.provision "shell", inline: "echo foo"

  config.vm.define "web" do |web|
    web.vm.provision "shell", inline: "echo bar"
  end

  config.vm.provision "shell", inline: "echo baz"
end

The ordering of the provisioners will be to echo "foo", "baz", then "bar" (note the second one might not be what you expect!). Remember: ordering is outside in.

With multiple provisioners, use the --provision-with setting along with names to get more fine grained control over what is run and when.

Overriding Provisioner Settings

Warning: Advanced Topic! Provisioner overriding is an advanced topic that really only becomes useful if you are already using multi-machine and/or provider overrides. If you are just getting started with Vagrant, you can safely skip this.

When using features such as multi-machine or provider-specific overrides, you may want to define common provisioners in the global configuration scope of a Vagrantfile, but override certain aspects of them internally. Vagrant allows you to do this, but has some details to consider.

To override settings, you must assign a name to your provisioner.

Vagrant.configure("2") do |config|
  config.vm.provision "foo", type: "shell",
    inline: "echo foo"

  config.vm.define "web" do |web|
    web.vm.provision "foo", type: "shell",
      inline: "echo bar"
  end
end

In the above, only "bar" will be echoed, because the inline setting overloaded the outer provisioner. This overload is only effective within that scope: the "web" VM. If there were another VM defined, it would still echo "foo" unless it itself also overloaded the provisioner.

Be careful with ordering. When overriding a provisioner in a sub-scope, the provisioner will run at that point. In the example below, the output would be "foo" then "bar":

Vagrant.configure("2") do |config|
  config.vm.provision "foo", type: "shell",
    inline: "echo ORIGINAL!"

  config.vm.define "web" do |web|
    web.vm.provision "shell",
      inline: "echo foo"
    web.vm.provision "foo", type: "shell",
      inline: "echo bar"
  end
end

If you want to preserve the original ordering, you can specify the preserve_order: true flag:

Vagrant.configure("2") do |config|
  config.vm.provision "do-this",
    type: "shell",
    preserve_order: true,
    inline: "echo FIRST!"
  config.vm.provision "then-this",
    type: "shell",
    preserve_order: true,
    inline: "echo SECOND!"
end