178 lines
7.9 KiB
Markdown
178 lines
7.9 KiB
Markdown
---
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description: |
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With Packer installed, let's just dive right into it and build our first image.
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Our first image will be an Amazon EC2 AMI with Redis pre-installed. This is just
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an example. Packer can create images for many platforms with anything
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pre-installed.
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layout: intro
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next_title: Provision
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next_url: '/intro/getting-started/provision.html'
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page_title: Build an Image
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prev_url: '/intro/getting-started/setup.html'
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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 image.
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Our first image will be an [Amazon EC2 AMI](https://aws.amazon.com/ec2/) with
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Redis pre-installed. This is just an example. Packer can create images for [many
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platforms](/intro/platforms.html) with anything pre-installed.
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If you don't have an AWS account, [create one now](https://aws.amazon.com/free/).
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For the example, we'll use a "t2.micro" instance to build our image, which
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qualifies under the AWS [free-tier](https://aws.amazon.com/free/), meaning it
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will be free. If you already have an AWS account, you may be charged some amount
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of money, but it shouldn't be more than a few cents.
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-> **Note:** If you're not using an account that qualifies under the AWS
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free-tier, you may be charged to run these examples. The charge should only be a
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few cents, but we're not responsible if it ends up being more.
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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](https://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 is called
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a *template* in Packer terminology. The format of a template is simple
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[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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``` {.javascript}
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{
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"variables": {
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"aws_access_key": "",
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"aws_secret_key": ""
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},
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"builders": [{
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"type": "amazon-ebs",
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"access_key": "{{user `aws_access_key`}}",
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"secret_key": "{{user `aws_secret_key`}}",
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"region": "us-east-1",
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"source_ami": "ami-72b9e018",
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"instance_type": "t2.micro",
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"ssh_username": "ubuntu",
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"ami_name": "packer-example {{timestamp}}"
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}]
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}
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```
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When building, you'll pass in the `aws_access_key` and `aws_secret_key` as a
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[user variable](/docs/templates/user-variables.html), keeping your secret keys
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out of the template. You can create security credentials on [this
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page](https://console.aws.amazon.com/iam/home?#security_credential). An example
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IAM policy document can be found in the [Amazon EC2 builder
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docs](/docs/builders/amazon.html).
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This is a basic template that is ready-to-go. It should be immediately
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recognizable as a normal, basic JSON object. Within the object, the `builders`
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section 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 and
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turning that machine into an image.
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In this case, we're only configuring a single builder of type `amazon-ebs`. This
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is the Amazon EC2 AMI builder that ships with Packer. This builder builds an
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EBS-backed AMI by launching a source AMI, provisioning on top of that, and
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re-packaging it into a new AMI.
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The additional keys within the object are configuration for this builder,
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specifying things 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 specific to
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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
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template by running `packer validate example.json`. This command checks the
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syntax as well as the configuration values to verify they look valid. The output
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should 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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``` {.text}
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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 image with
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Redis pre-installed, and yet the template we made doesn't reference Redis
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anywhere. In fact, this part of the documentation will only cover making a first
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basic, non-provisioned image. The next section on provisioning will cover
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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. This
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is done by calling `packer build` with the template file. The output should look
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similar to below. Note that this process typically takes a few minutes.
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``` {.text}
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$ packer build \
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-var 'aws_access_key=YOUR ACCESS KEY' \
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-var 'aws_secret_key=YOUR SECRET KEY' \
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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* that were
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created as part of the build. Artifacts are the results of a build, and
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typically represent an ID (such as in the case of an AMI) or a set of files
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(such as for a VMware virtual machine). In this example, we only have a single
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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 right now
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and it would work great.
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-> **Note:** Your AMI ID will surely be different than the one above. If you
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try to launch the one in the example output above, you will get an error. If you
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want to try to launch your AMI, get the ID from the Packer output.
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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. After
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they're built, it is up to you to launch or destroy them as you see fit. If you
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want to store and namespace images for easy reference, you can use [Atlas by
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HashiCorp](https://atlas.hashicorp.com). We'll cover remotely building and
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storing images at the end of this getting started guide.
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After running the above example, your AWS account now has an AMI associated with
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it. AMIs are stored in S3 by Amazon, so unless you want to be charged about
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$0.01 per month, you'll probably want to remove it. Remove the AMI by first
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deregistering it on the [AWS AMI management
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page](https://console.aws.amazon.com/ec2/home?region=us-east-1#s=Images). Next,
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delete the associated snapshot on the [AWS snapshot management
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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 the
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image was pretty useless in this case (nothing was changed about it), this page
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should've given you a general idea of how Packer works, what templates are, and
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how to validate and build templates into machine images.
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