github.com/hobbeswalsh/terraform@v0.3.7-0.20150619183303-ad17cf55a0fa/website/source/intro/getting-started/provision.html.md (about)

     1  ---
     2  layout: "intro"
     3  page_title: "Provision"
     4  sidebar_current: "gettingstarted-provision"
     5  description: |-
     6    You're now able to create and modify infrastructure. This page introduces how to use provisioners to run basic shell scripts on instances when they're created.
     7  ---
     8  
     9  # Provision
    10  
    11  You're now able to create and modify infrastructure. This page
    12  introduces how to use provisioners to run basic shell scripts on
    13  instances when they're created.
    14  
    15  If you're using an image-based infrastructure (perhaps with images
    16  created with [Packer](https://www.packer.io)), then what you've
    17  learned so far is good enough. But if you need to do some initial
    18  setup on your instances, provisioners let you upload files,
    19  run shell scripts, etc.
    20  
    21  ## Defining a Provisioner
    22  
    23  To define a provisioner, modify the resource block defining the
    24  "example" EC2 instance to look like the following:
    25  
    26  ```
    27  resource "aws_instance" "example" {
    28  	ami = "ami-aa7ab6c2"
    29  	instance_type = "t1.micro"
    30  
    31  	provisioner "local-exec" {
    32  		command = "echo ${aws_instance.example.public_ip} > file.txt"
    33  	}
    34  }
    35  ```
    36  
    37  This adds a `provision` block within the `resource` block. Multiple
    38  `provision` blocks can be added to define multiple provisioning steps.
    39  Terraform supports
    40  [multiple provisioners](/docs/provisioners/index.html),
    41  but for this example we use the "local-exec" provisioner.
    42  
    43  The "local-exec" provisioner executes a command locally on the machine
    44  running Terraform. We're using this provisioner versus the others so
    45  we don't have to worry about specifying any
    46  [connection info](/docs/provisioners/connection.html) right now.
    47  
    48  ## Running Provisioners
    49  
    50  Provisioners are run only when a resource is _created_. They
    51  are not a replacement for configuration management and changing
    52  the software of an already-running server, and are instead just
    53  meant as a way to bootstrap a server. For configuration management,
    54  you should use Terraform provisioning to invoke a real configuration
    55  management solution.
    56  
    57  Make sure that your infrastructure is
    58  [destroyed](/intro/getting-started/destroy.html) if it isn't already,
    59  then run `apply`:
    60  
    61  ```
    62  $ terraform apply
    63  aws_instance.example: Creating...
    64    ami:           "" => "ami-aa7ab6c2"
    65    instance_type: "" => "t1.micro"
    66  aws_eip.ip: Creating...
    67    instance: "" => "i-213f350a"
    68  
    69  Apply complete! Resources: 2 added, 0 changed, 0 destroyed.
    70  ```
    71  
    72  Terraform will output anything from provisioners to the console,
    73  but in this case there is no output. However, we can verify
    74  everything worked by looking at the "file.txt" file:
    75  
    76  ```
    77  $ cat file.txt
    78  54.192.26.128
    79  ```
    80  
    81  It contains the IP, just as we asked!
    82  
    83  ## Failed Provisioners and Tainted Resources
    84  
    85  If a resource successfully creates but fails during provision,
    86  Terraform will error and mark the resource as "tainted." A
    87  resource that is tainted has been physically created, but can't
    88  be considered safe to use since provisioning failed.
    89  
    90  When you generate your next execution plan, Terraform will remove
    91  any tainted resources and create new resources, attempting to
    92  provision again. It does not attempt to restart provisioning on the
    93  same resource because it isn't guaranteed to be safe.
    94  
    95  Terraform does not automatically roll back and destroy the resource
    96  during the apply when the failure happens, because that would go
    97  against the execution plan: the execution plan would've said a
    98  resource will be created, but does not say it will ever be deleted.
    99  But if you create an execution plan with a tainted resource, the
   100  plan will clearly state that the resource will be destroyed because
   101  it is tainted.
   102  
   103  ## Next
   104  
   105  Provisioning is important for being able to bootstrap instances.
   106  As another reminder, it is not a replacement for configuration
   107  management. It is meant to simply bootstrap machines. If you use
   108  configuration management, you should use the provisioning as a way
   109  to bootstrap the configuration management utility.
   110  
   111  In the next section, we start looking at [variables as a way to
   112  parameterize our configurations](/intro/getting-started/variables.html).