COLA - Container Linux Appliance

COLA is set of tools to build customized Flatcar Container Linux configurations and images. It includes a transpiler to convert a high-level HCL based configuration to a low-level Ignition configuration. It is still in early development and breaking changes are to be expected.

Example

# machine.hcl
system {
  hostname = "my-machine"
}

user "admin" {
  groups = ["sudo"]
  ssh_authorized_keys = [
    "ssh-ed25519 AAAAAAAA...",
  ]
}

container "nginx" {
  image = "nginx:latest"

  volume "/usr/share/nginx/html" {
    source = "/var/www"
  }
}

extension "tailscale" {
  version = "1.76.6"
  arch = "x86-64"
  bakery_url = "https://github.com/flatcar/sysext-bakery/releases/download/latest/"
}

Installation

Download a release from the GitHub Releases page, or build from source:

go install github.com/tmacro/cola/cmd/cola@latest

Confirm it’s installed:

cola --help

You should see usage information for cola.

Usage

Global Flags

All cola commands support the following global flags:

• --log-level="debug" Sets the log level. Possible values might include debug, info, warn, error.

• --log-format="text" Sets the log output format. Possible values are text or json.

Commands

generate

Generates an Ignition config.

Usage: cola generate [flags]

Generate an Ignition config.

Flags:
  -h, --help                    Show help information.
      --log-level="debug"       Set the log level.
      --log-format="text"       Set the log format. (json, text)
  -c, --config=CONFIG,...       Path to the configuration file or directory.
  -o, --output=STRING           Output file.
  -b, --bundled-extensions      Assume extensions will be bundled into the image.
  -e, --extension-dir=STRING    Directory containing sysexts.

Example:

cola generate \
  --config=machine.hcl \
  --config=extra-configs/ \
  --output=machine.ign \
  --extension-dir=./extensions

bundle

Bundles sysexts and an Ignition config into a self-contained Flatcar Linux image.

Usage: cola bundle --image=STRING [flags]

Bundle sysexts and an Ignition config with a Flatcar Linux image.

Flags:
  -h, --help                    Show help information.
      --log-level="debug"       Set the log level.
      --log-format="text"       Set the log format. (json, text)
  -c, --config=CONFIG,...       Path to the configuration file or directory.
      --base=BASE,...           Use this config as a base to extend from.
  -f, --image=STRING            Path to the Flatcar Linux image.
  -g, --gen-ignition            Generate the Ignition config. (cannot be used with --ignition)
  -i, --ignition=STRING         Path to the Ignition config.
  -o, --output=STRING           Output file.
  -e, --extension-dir=STRING    Directory containing sysexts.

Example:

cola bundle \
  --image=flatcar.img \
  --config=machine.hcl \
  --extension-dir=./extensions \
  --output=bundled-flatcar.img \
  --log-level=info