website: build/provision
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Mitchell Hashimoto
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---
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layout: "intro"
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page_title: "Build an Image"
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prev_url: "/intro/getting-started/setup.html"
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next_url: "/intro/getting-started/provision.html"
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next_title: "Provision"
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---
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# Build an Image
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With Packer installed, let's just dive right into it and build our first
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image. Our first image will be an [Amazon EC2 AMI](http://aws.amazon.com/ec2/)
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with Redis pre-installed. This is just an example. Packer can create images
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for [many platforms](/intro/platforms.html) with anything pre-installed.
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If you don't have an AWS account, [create one now](http://aws.amazon.com/free/).
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For the example, we'll use a "t1.micro" instance to build our image, which
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qualifies under the AWS [free-tier](http://aws.amazon.com/free/), meaning
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it will be free. If you already have an AWS account, you may be charged some
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amount of money, but it shouldn't be more than a few cents.
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<div class="alert alert-block alert-warn">
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<strong>Note</strong> that if you're not using an account that qualifies under
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the AWS <a href="http://aws.amazon.com/free/">free-tier</a>, you may be
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charged to run these examples. The charge should only be a few cents, but
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we're not responsible if it ends up being more.
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</div>
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Packer can build images for [many platforms](/intro/platforms.html) other than
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AWS, but AWS requires no additional software installed on your computer and
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their [free-tier](http://aws.amazon.com/free/) makes it free to use for most
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people. This is why we chose to use AWS for the example. If you're uncomfortable
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setting up an AWS account, feel free to follow along as the basic principles
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apply to the other platforms as well.
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## The Template
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The configuration file used to define what image we want built and how
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is called a _template_ in Packer terminology. The format of a template
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is simple [JSON](http://www.json.org/). JSON struck the best balance between
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human-editable and machine-editable, allowing both hand-made templates as well
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as machine generated templates to easily be made.
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We'll start by creating the entire template, then we'll go over each section
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briefly. Create a file `example.json` and fill it with the following contents:
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<pre class="prettyprint">
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{
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"builders": [{
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"type": "amazon-ebs",
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"access_key": "YOUR KEY HERE",
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"secret_key": "YOUR SECRET KEY HERE",
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"region": "us-east-1",
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"source_ami": "ami-de0d9eb7",
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"instance_type": "t1.micro",
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"ssh_username": "ubuntu",
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"ami_name": "packer-example {{.CreateTime}}"
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}]
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}
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</pre>
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Please fill in the `access_key` and `secret_key` with the proper values
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for your account. Your security credentials can be found on
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[this page](https://console.aws.amazon.com/iam/home?#security_credential).
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This is a basic template that is ready-to-go. It should be immediately recognizable
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as a normal, basic JSON object. Within the object, the `builders` section
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contains an array of JSON objects configuring a specific _builder_. A
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builder is a component of Packer that is responsible for creating a machine
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and turning that machine into an image.
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In this case, we're only configuring a single builder of type `amazon-ebs`.
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This is the Amazon EC2 AMI builder that ships with Packer. This builder
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builds an EBS-backed AMI by launching a source AMI, provisioning on top of
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that, and re-packaging it into a new AMI.
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The additional keys within the object are configuration for this builder, specifying things
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such as access keys, the source AMI to build from, and more.
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The exact set of configuration variables available for a builder are
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specific to each builder and can be found within the [documentation](/docs).
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Before we take this template and build an image from it, let's validate the template
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by running `packer validate example.json`. This command checks the syntax
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as well as the configuration values to verify they look valid. The output should
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look similar to below, because the template should be valid. If there are
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any errors, this command will tell you.
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```
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$ packer validate example.json
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Template validated successfully.
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```
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Next, let's build the image from this template.
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An astute reader may notice that we said earlier we'd be building an
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image with Redis pre-installed, and yet the template we made doesn't reference
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Redis anywhere. In fact, this part of the documentation will only cover making
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a first basic, non-provisioned image. The next section on provisioning will
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cover installing Redis.
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## Your First Image
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With a properly validated template. It is time to build your first image.
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This is done by calling `packer build` with the template file. The output
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should look similar to below. Note that this process typically takes a
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few minutes.
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```
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$ packer build example.json
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==> amazon-ebs: amazon-ebs output will be in this color.
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==> amazon-ebs: Creating temporary keypair for this instance...
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==> amazon-ebs: Creating temporary security group for this instance...
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==> amazon-ebs: Authorizing SSH access on the temporary security group...
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==> amazon-ebs: Launching a source AWS instance...
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==> amazon-ebs: Waiting for instance to become ready...
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==> amazon-ebs: Connecting to the instance via SSH...
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==> amazon-ebs: Stopping the source instance...
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==> amazon-ebs: Waiting for the instance to stop...
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==> amazon-ebs: Creating the AMI: packer-example 1371856345
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==> amazon-ebs: AMI: ami-19601070
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==> amazon-ebs: Waiting for AMI to become ready...
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==> amazon-ebs: Terminating the source AWS instance...
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==> amazon-ebs: Deleting temporary security group...
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==> amazon-ebs: Deleting temporary keypair...
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==> amazon-ebs: Build finished.
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==> Builds finished. The artifacts of successful builds are:
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--> amazon-ebs: AMIs were created:
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us-east-1: ami-19601070
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```
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At the end of running `packer build`, Packer outputs the _artifacts_
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that were created as part of the build. Artifacts are the results of a
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build, and typically represent an ID (such as in the case of an AMI) or
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a set of files (such as for a VMware virtual machine). In this example,
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we only have a single artifact: the AMI in us-east-1 that was created.
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This AMI is ready to use. If you wanted you can go and launch this AMI
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right now and it would work great.
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<div class="alert alert-block alert-info">
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<strong>Note:</strong> Your AMI ID will surely be different than the
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one above. If you try to launch the one in the example output above, you
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will get an error. If you want to try to launch your AMI, get the ID from
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the Packer output.
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</div>
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## Managing the Image
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Packer only builds images. It does not attempt to manage them in any way.
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After they're built, it is up to you to launch or destroy them as you see
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fit. As a result of this, after running the above example, your AWS account
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now has an AMI associated with it.
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AMIs are stored in S3 by Amazon, so unless you want to be charged about $0.01
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per month, you'll probably want to remove it. Remove the AMI by
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first deregistering it on the [AWS AMI management page](https://console.aws.amazon.com/ec2/home?region=us-east-1#s=Images).
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Next, delete the associated snapshot on the
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[AWS snapshot management page](https://console.aws.amazon.com/ec2/home?region=us-east-1#s=Snapshots).
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Congratulations! You've just built your first image with Packer. Although
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the image was pretty useless in this case (nothing was changed about it),
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this page should've given you a general idea of how Packer works, what
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templates are, and how to validate and build templates into machine
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images.
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---
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layout: "intro"
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page_title: "Provision"
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prev_url: "/intro/getting-started/build-image.html"
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next_url: "/intro/getting-started/parallel-builds.html"
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next_title: "Parallel Builds"
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---
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# Provision
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In the previous page of this guide, you created your first image with
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Packer. The image you just built, however, was basically just a repackaging
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of a previously existing base AMI. The real utility of Packer comes from
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being able to install and configure software into the images as well.
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This stage is also known as the _provision_ step. Packer fully supports
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automated provisioning in order to install software onto the machines prior
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to turning them into images.
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In this section, we're going to complete our image by installing
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Redis on it. This way, the image we end up building actually contains
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Redis pre-installed. Although Redis is a small, simple example, this should
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give you an idea of what it may be like to install many more packages into
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the image.
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Historically, pre-baked images have been frowned upon because changing
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them has been so tedious and slow. Because Packer is completely automated,
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including provisioning, images can be changed quickly and integrated with
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modern configuration management tools such as Chef or Puppet.
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## Configuring Provisioners
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Provisioners are configured as part of the template. We'll use the built-in
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shell provisioner that comes with Packer to install Redis. Modify the
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`example.json` template we made previously and add the following. We'll
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explain the various parts of the new configuration following the code
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block below.
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<pre class="prettyprint">
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{
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"builders": [...],
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"provisioners": [{
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"type": "shell",
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"inline": [
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"sudo apt-get update",
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"sudo apt-get install -y redis-server"
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]
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}]
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}
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</pre>
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Hopefully it is obvious, but the `builders` section shouldn't actually
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contain "...", it should be the contents setup in the previous page
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of the getting started guide.
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To configure the provisioners, we add a new section `provisioners` to the
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template, alongside the `builders` configuration. The provisioners section
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is an array of provisioners to run. If multiple provisioners are specified, they
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are run in the order given.
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By default, each provisioner is run for every builder defined. So if we had
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two builders defined in our template, such as both Amazon and DigitalOcean, then
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the shell script would run as part of both builds. There are ways to restrict
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provisioners to certain builds, but it is outside the scope of this getting
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started guide. It is covered in more detail in the complete
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[documentation](/docs).
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The one provisioner we defined has a type of `shell`. This provisioner
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ships with Packer and runs shell scripts on the running machine. In our
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case, we specify two inline commands to run in order to install Redis.
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## Build
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With the provisioner configured, give it a pass once again through
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`packer validate` to verify everything is okay, then build it using
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`packer build example.json`. The output should look similar to when you
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built your first image, except this time there will be a new step where
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the provisoning is run.
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The output from the provisioner is too verbose to include in this
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guide, since it contains all the output from the shell scripts. But you
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should see Redis successfully install. After that, Packer once again
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turns the machine into an AMI.
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If you were to launch this AMI, Redis would be pre-installed. Cool!
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This is just a basic example. In a real world use case, you may be provisioning
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an image with the entire stack necessary to run your application. Or maybe
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just the web stack so that you can have an image for web servers pre-built.
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This saves tons of time later as you launch these images since everything
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is pre-installed. Additionally, since everything is pre-installed, you
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can test the images as they're built and know that when they go into
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production, they'll be functional.
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@ -13,8 +13,8 @@
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<ul>
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<li><h4>Getting Started</h4></li>
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<li><a href="/intro/getting-started/setup.html">Install Packer</a></li>
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<li><a href="#">Build an Image</a></li>
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<li><a href="#">Provision</a></li>
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<li><a href="/intro/getting-started/build-image.html">Build an Image</a></li>
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<li><a href="/intro/getting-started/provision.html">Provision</a></li>
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<li><a href="#">Parallel Builds</a></li>
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<li><a href="#">Post-Process</a></li>
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</ul>
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@ -142,11 +142,15 @@
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padding: $docs-top-margin 80px;
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display: block;
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p code {
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font-size: 14px;
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}
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code {
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background-color: #000;
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border: 0;
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color: #b1d631;
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font-size: 14px;
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font-size: 12px;
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}
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a {
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@ -193,7 +197,7 @@
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pre {
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border: 0;
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font-size: 14px;
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font-size: 12px;
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margin-left: -80px;
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margin-right: -80px;
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padding-top: 40px;
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