Base Image Factory

This provisions a Base Image from a previously created Root Image.

A note on terminology

We use Root Image to mean a completely unprovisioned bare image with nothing beyond a basic OS install. We use Base Image to mean a partially provisioned image with services required by all operational servers, e.g. monitoring, log aggregation, telemetry, etc.

Setup

Basic Tooling

First setup Homebrew, and make sure everything is up to date.

Clone this repo and cd into it. Run the following to set up tools:

brew bundle

When setting things up, you will need to download a copy of the fork of Packer we use from here: https://github.com/AlexSc/packer/releases/tag/v1.7.5-dev3

Unzip and put the file in ~/bin.

Secrets

Copy secrets.auto.pkrvars.hcl.template to secrets.auto.pkrvars.hcl, and populate all the variables listed within.

Image Specifications

When this image provides the option to include additional configuration files in a directory, file names must be prefixed with two digits and end in .conf. The prefixes 00 to 29 and 90 to 95 are reserved for use by this image.

TEAK_SERVICE

The Base Image configures systemd to provide a TEAK_SERVICE environment variable to all systemd services with names starting with teak-. By default TEAK_SERVICE will be set to the name of the base image AMI. In non-AMI environments, TEAK_SERVICE will be set to "unknown". To modify this create a configuration file in /etc/systemd/system/teak-.service.d/ with the contents

[Service]
Environment="TEAK_SERVICE={{service_name}}"

teak-init.target

The Base Image provides teak-init.target, which will not be active until all services provided by the Base Image are available. Downstream services should set After=teak-init.target in their unit configurations.

Fluentd

The Base Image provides Fluentd as teak-log-collector, with the following defaults:

systemd, cloudinit, fluentd, and configurator logs are tailed under ancillary.{process}
ancillary logs are outputted to cloudwatch_logs under /mj/server/{{ server_environment }}/ancillary/{{ process_name }}:{{ service_name }}.{{ hostname }}
logs with the service.default tag will be outputted to /mj/server/{{ server_environment }}/service/{{ service_name }}:{{ service_name }}.{{ hostname }}
Downstream images may add additional configuration for fluentd in /etc/fluent/conf.d/*.conf.

Fluentd is enabled by default in this image.

Disabling Fluentd

To disable Fluentd at boot, use the following user-data

#cloud-config
bootcmd:
  - [systemctl, stop, --no-block, teak-log-collector]

Be sure to wipe /var/lib/cloud after provisioning so that this user-data does not persist to live servers.

It is recommended that Fluentd remain enabled so that the server logs from the build process running be logged to CloudWatch.

Config O-Mat

The Base Image provides the config_o_mat as teak-configurator.

teak-configurator is enabled by default in this image.

As the Base Image provides no "metaconfiguration" for the configurator it will not actually do anything.

Adding a New Language

cd language_images
cp -Rfp <some_existing_language> <new_language> # Note:  Don't put trailing slashes on the directory names!
ls -la <new_language>/image.pkr.hcl
# You should see something like:
# lrwxr-xr-x  1 jonathonfrisby  staff  24 Feb  8 11:55 ruby314/image.pkr.hcl -> ../../base_image.pkr.hcl

# If, and only if, the file is _not_ a symlink, then do the following:
cd <new_language>
rm image.pkr.hcl
ln -sfn ../../base_image.pkr.hcl image.pkr.hcl # We want this to be a symlink to the base one!

# Once the directory is set up, with the Packer definition being a symlink:
#
# Edit image.auto.pkrvars.hcl to change `ami_prefix` and `cost_center`.
#
# Edit playbooks as appropriate.

Now, you'll need to add the appropriate blocks in .circleci/config.yml. Use an existing language as a guide, and note that you need to add blocks in both references and workflows.

New Ruby Versions

Start from the most recent, relevant Ruby image, copying to a new folder with an appropriate name as per the general instructions.

In the language_images/rubyXX/playbooks/ruby.yml file, look for lines that look like this:

        RUBY_SERIES: "3.0"
        RUBY_VERSION: "3.0.3"
        RUBY_CHECKSUM: 3586861cb2df56970287f0fd83f274bd92058872d830d15570b36def7f1a92ac

Revise these with appropriate values (use .tar.gz version, and SHA256 checksum!), from the official website.

Provisioning

To build Debian 11 base AMIs:

~/bin/packer_1.7.5-dev3_darwin_arm64 init .

aws-vault exec mrjoy -- ~/bin/packer_1.7.5-dev3_darwin_arm64 build --var-file=base_image.auto.pkrvars.hcl --var-file=secrets.auto.pkrvars.hcl -var region=us-east-1 -var build_account_canonical_slug=stage-ci-cd -var use_generated_security_group=true -var cost_center=root_image -timestamp-ui base_image.pkr.hcl

To build Debian 11 language-specific AMIs, first build a base AMI and then:

cd language_images/<language>/

~/bin/packer_1.7.5-dev3_darwin_arm64 init .

aws-vault exec mrjoy -- ~/bin/packer_1.7.5-dev3_darwin_arm64 build -var-file=image.auto.pkrvars.hcl --var-file=secrets.auto.pkrvars.hcl -var region=us-east-1 -var build_account_canonical_slug=stage-ci-cd -var use_generated_security_group=true -var cost_center=root_image -timestamp-ui image.pkr.hcl

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