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Injection is a simple utility that consumes and processes CoreOS Ignition configs on already-running hosts.

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Injection

Injection is a simple utility that consumes and processes Ignition configs and writes out directories, files, and systemd units (and enables/disables them!) on an already-running Linux host, differing from Ignition, which is only intended to configure immutable Fedora/RedHat CoreOS hosts on first boot.

In conjunction with Butane, this allows you to build human-readable configuration files that can be used to easily (re)configure existing hosts.

Prerequisites

  • Linux/macOS
  • Butane, if you're planning on using Butane to generate Ignition configs (recommended)

Installation

AMD64

sudo wget https://github.com/andygeorge/injection/releases/download/v0.1.1-beta/injection-amd64-linux -O /usr/local/bin/injection && sudo chmod a+x /usr/local/bin/injection

ARM32 (eg Raspberry Pi)

sudo wget https://github.com/andygeorge/injection/releases/download/v0.1.1-beta/injection-arm32-linux -O /usr/local/bin/injection && sudo chmod a+x /usr/local/bin/injection

Or, manually:

Example

  • Clone and enter this repo
gh repo clone andygeorge/injection
cd injection
  • Use the example Butane config file:
mkdir example_files && cp example_butane.bu example_files/example.bu
  • The file example_files/example.bu should be populated

  • Create an Ignition config using Butane:

butane --strict example_files/example.bu > example_files/example.ign
  • The file example_files/example.ign should be populated and look like this:
{"ignition":{"version":"3.3.0"},"storage":{"directories":[{"path":"/tmp/example","mode":493}],"files":[{"path":"/tmp/example/hello_world.txt","contents":{"compression":"","source":"data:,Hello%2C%20world!%0A"},"mode":420},{"path":"/tmp/example/hello_world_gzip.txt","contents":{"compression":"gzip","source":"data:;base64,H4sIAAAAAAAC/zSQQc4UOwyE9+8UdYBRn+IhgcQSxNoknu6Skjjj2MOI06MwP7soicv1fd8uLnBB0LNcaOKnOj5ra4Yf5q3izqaISwK/2BpyKc7fnCjWp+tatAEOxKX4cg4GbRz4aq4dnCs7qjVzLAaka9xQbCwtoZEOqZxcLBwntDFuWFpRDcpc3SpC+zQHR2FlzRHIQJOf5gqNd7aiyzkE0vhIOfA9oIMdUtG5D08dlH7DI7kwbIVnhb7UC0N2YWRr0ou9k/cnLu5NfyM5oS+obORu1d4Ej5Q48P+OlAwFPV0/YDngOl0vHVWdsS+e1nKGhOK5SaFrKQpb+6dIoYl7npTA2IUwxSmRfuDTq+gMze1xBKwU0SKBkpNVYk/YwHRj1bEtblMcKNmmbG7Y/c5CQdWlvl+7tV1DtiBW6Prwmv34708AAAD//9sohz4WAgAA"},"mode":420}]},"systemd":{"units":[{"contents":"[Unit]\nDescription=Hello world service\n\n[Service]\nType=oneshot\nExecStart=/usr/bin/echo \"hello world\"\nStandardOutput=journal\n\n[Install]\nWantedBy=multi-user.target default.target\n","enabled":true,"name":"hello-world.service"}]}}
  • Run Injection:
sudo injection example_files/example.ign

This will write out the directories, files, and systemd units defined in the example:

/tmp/example
/tmp/example2
/tmp/example3/example4
/tmp/example/hello_world.txt
/tmp/example/hello_world_gzip.txt
/etc/systemd/system/hello-world.service

Ignition support

This only has basic Ignition support for a few specific fields:

  • storage:files
  • storage:directories
  • systemd:units

Support for passwd:users is planned.


injection-go

injection built in Go.

# generate ignition
butane --strict ../example_files/example.bu > ../example_files/example.ign

# build injection
go mod tidy && go fmt *.go && go build -o build/

# run injection
./build/injection ../example_files/example.ign

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Injection is a simple utility that consumes and processes CoreOS Ignition configs on already-running hosts.

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