github.com/ratanraj/packer@v1.3.2/website/source/docs/templates/provisioners.html.md (about)

     1  ---
     2  description: |
     3      Within the template, the provisioners section contains an array of all the
     4      provisioners that Packer should use to install and configure software within
     5      running machines prior to turning them into machine images.
     6  layout: docs
     7  page_title: 'Provisioners - Templates'
     8  sidebar_current: 'docs-templates-provisioners'
     9  ---
    10  
    11  # Template Provisioners
    12  
    13  Within the template, the provisioners section contains an array of all the
    14  provisioners that Packer should use to install and configure software within
    15  running machines prior to turning them into machine images.
    16  
    17  Provisioners are *optional*. If no provisioners are defined within a template,
    18  then no software other than the defaults will be installed within the resulting
    19  machine images. This is not typical, however, since much of the value of Packer
    20  is to produce multiple identical images of pre-configured software.
    21  
    22  This documentation page will cover how to configure a provisioner in a template.
    23  The specific configuration options available for each provisioner, however, must
    24  be referenced from the documentation for that specific provisioner.
    25  
    26  Within a template, a section of provisioner definitions looks like this:
    27  
    28  ``` json
    29  {
    30    "provisioners": [
    31      // ... one or more provisioner definitions here
    32    ]
    33  }
    34  ```
    35  
    36  For each of the definitions, Packer will run the provisioner for each of the
    37  configured builds. The provisioners will be run in the order they are defined
    38  within the template.
    39  
    40  ## Provisioner Definition
    41  
    42  A provisioner definition is a JSON object that must contain at least the `type`
    43  key. This key specifies the name of the provisioner to use. Additional keys
    44  within the object are used to configure the provisioner, with the exception of a
    45  handful of special keys, covered later.
    46  
    47  As an example, the "shell" provisioner requires a key such as `script` which
    48  specifies a path to a shell script to execute within the machines being created.
    49  
    50  An example provisioner definition is shown below, configuring the shell
    51  provisioner to run a local script within the machines:
    52  
    53  ``` json
    54  {
    55    "type": "shell",
    56    "script": "script.sh"
    57  }
    58  ```
    59  
    60  ## Run on Specific Builds
    61  
    62  You can use the `only` or `except` configurations to run a provisioner only with
    63  specific builds. These two configurations do what you expect: `only` will only
    64  run the provisioner on the specified builds and `except` will run the
    65  provisioner on anything other than the specified builds.
    66  
    67  An example of `only` being used is shown below, but the usage of `except` is
    68  effectively the same:
    69  
    70  ``` json
    71  {
    72    "type": "shell",
    73    "script": "script.sh",
    74    "only": ["virtualbox-iso"]
    75  }
    76  ```
    77  
    78  The values within `only` or `except` are *build names*, not builder types. If
    79  you recall, build names by default are just their builder type, but if you
    80  specify a custom `name` parameter, then you should use that as the value instead
    81  of the type.
    82  
    83  ## Build-Specific Overrides
    84  
    85  While the goal of Packer is to produce identical machine images, it sometimes
    86  requires periods of time where the machines are different before they eventually
    87  converge to be identical. In these cases, different configurations for
    88  provisioners may be necessary depending on the build. This can be done using
    89  build-specific overrides.
    90  
    91  An example of where this might be necessary is when building both an EC2 AMI and
    92  a VMware machine. The source EC2 AMI may setup a user with administrative
    93  privileges by default, whereas the VMware machine doesn't have these privileges.
    94  In this case, the shell script may need to be executed differently. Of course,
    95  the goal is that hopefully the shell script converges these two images to be
    96  identical. However, they may initially need to be run differently.
    97  
    98  This example is shown below:
    99  
   100  ``` json
   101  {
   102    "type": "shell",
   103    "script": "script.sh",
   104    "override": {
   105      "vmware-iso": {
   106        "execute_command": "echo 'password' | sudo -S bash {{.Path}}"
   107      }
   108    }
   109  }
   110  ```
   111  
   112  As you can see, the `override` key is used. The value of this key is another
   113  JSON object where the key is the name of a [builder
   114  definition](/docs/templates/builders.html). The value of this is in turn another
   115  JSON object. This JSON object simply contains the provisioner configuration as
   116  normal. This configuration is merged into the default provisioner configuration.
   117  
   118  ## Pausing Before Running
   119  
   120  With certain provisioners it is sometimes desirable to pause for some period of
   121  time before running it. Specifically, in cases where a provisioner reboots the
   122  machine, you may want to wait for some period of time before starting the next
   123  provisioner.
   124  
   125  Every provisioner definition in a Packer template can take a special
   126  configuration `pause_before` that is the amount of time to pause before running
   127  that provisioner. By default, there is no pause. An example is shown below:
   128  
   129  ``` json
   130  {
   131    "type": "shell",
   132    "script": "script.sh",
   133    "pause_before": "10s"
   134  }
   135  ```
   136  
   137  For the above provisioner, Packer will wait 10 seconds before uploading and
   138  executing the shell script.