jlk / tf-testing

just using this to test some terraform/terrascan/atlantis related things

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Terraform config to create alpine package repository

This terraform configuration will create a mirror of the Alpline Linux package repository on a CentOS 7 system.

This is based on a page from the Alpine Linux wiki

To use this project, you need Terraform. To install, either download or on macs with homebrew run brew install terraform.

Prerequisites

The first thing to determine is how much of the Alpine repository you wish to mirror, and how much disk space that will require. By default, the mirroring script at provisioning-scripts/rsync-alpine-repo.sh will mirror EVERYTHING. This requires around 530GB of disk.

Most folks will want a little less; Editing lines around 17 in the script allow excluding unwanted releases. As an example, the following would exclude releases before 3.6:

EXCLUDES="v2.* edge v3.0 v3.1 v3.2 v3.3 v3.4 v3.5"

To determine how much disk space is needed for a specific set of releases, a calculate-mirror-size.sh script is included. As with the rsync-alpine-repo.sh script, there is a desired_releases variable that can be customized to have the script calulate the required storage space. One thing to note - in this script you specify the releases you want, not the ones to exclude - so to get everything since v3.6 (as of May 2019), the variable would be set like:

desired_releases="v3.6 v3.7 v3.8"

One note: calculate-mirror-size.sh calculates storage requirements without actually downloading everything. It should run in about a minute.

Also note that you may want to make the volume larger than is needed today, to be able to handle newly added packages, as well as new Alpine releases.

Using with AWS

This uses Terraform's AWS "provider." Instructions to set up authentication are here, but the two popular places it will look for your AWS credentials in either

  • ~/.aws/credentials - Instructions to set this up are here
  • AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables

Getting Started

Before running for the first time, the terraform environment will need to be initialized:

terraform init

Next, to apply the configuration, several variables need to be set (see Variables, below). Once those are figured out, terraform can be run with a command similar to the following:

terraform apply -var ssh_keypair_name=my-keypair -var vpc_id=vpc-971323fa -var subnet_id=subnet-166323

This will create an EC2 instance with a new security group allowing in ssh and http access from the world, an EBS volume of 150GB for storing mirrored packages.

Upon successful deployment, the system's IP address will be displayed:

Apply complete! Resources: 5 added, 0 changed, 0 destroyed.

Outputs:

instance_ip_addr = 54.202.233.242

As it is a CentOS system, the default ssh user is centos.

Once the mirror is synchronized to the host, it can be accessed via http://<server-ip>/alpine

Actual Mirroring

If left alone, this terraform configuration will set up a cron job that runs daily (via of cron.daily). To get a start on things, you may ssh into the new system and run the sync manually with:

sudo /etc/cron.daily/rsync-alpine-repo.sh

Note this command will take probably hours to run, depending on configuration. If you network connection is not reliable, you may wish to execute this command inside screen, mux, or similar utility.

Cleaning up

To remove resources created by this configuration, run terraform similar as to create, but replace apply with destroy:

terraform destroy -var ssh_keypair_name=my-keypair -var vpc_id=vpc-971323fa -var subnet_id=subnet-166323

Variables

By default, the script runs with "reasonable" defaults. The following variables can be used to override defaults:

Variable name Required Description Default Value
ssh_keypair_name * Name of ssh keypair defined in EC2 to allow ssh into system
subnet_id * Subnet ID of where to install mirror
vpc_id * VPC ID of where to install mirror
availability_zone AWS AZ of where to install mirror us-west-2
http_acl List of CIDR blocks to allow http traffic from ["0.0.0.0/0"]
region AWS Region of where to install mirror us-west-2a
ssh_acl List of CIDR blocks to allow ssh traffic from ["0.0.0.0/0"]
storage_size Size of volume to create to store mirrored packages (GB) 150

TODO

There's several ways this configuration could be improved. Some that come to mind, are...

  • Reboot host after the build to ensure updates are fully applied.
  • Adding either an ELB or EIP to provide a consistent address to connect to
  • Currently this config is AWS-specific; I'd like to add support for other tf provisioners, but the lack of logic/flow control in Terraform is not thrilling me.
  • Allow specifying architecture(s) to mirror (right now mirroring aarch64, armhf, armv7, ppc64le, s390x, x86, x86_64)

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just using this to test some terraform/terrascan/atlantis related things

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