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go2chef: "just enough Go to get to Chef"

What is go2chef?

go2chef is a Go tool for bootstrapping Chef installations in a flexible and self-contained way. With go2chef, our goal is to make bootstrapping any node in a Chef deployment as simple as "get go2chef onto a machine and run it"

Requirements

Build Dependencies

go2chef requires Go 1.12+ for appropriate module support. Library dependencies are enumerated in the go.mod file in the repository root.

go2chef has no runtime dependencies.

Quickstart Example

Installing

go2chef is packaged in Fedora as of Fedora 32. It can be installed with:

$ sudo dnf install go2chef

Building

Build go2chef using make on Unix platforms:

$ make all		# build all variants to build/$GOOS/$GOARCH/go2chef
$ make linux		# ...or build platform-specific binaries
$ make darwin
$ make windows

On Windows, just build it using go build:

PS> mkdir build/windows/amd64
PS> go build -o build/windows/amd64/go2chef.exe ./bin

Configuring

Create a configuration file. For example, to install Chef and then download and install a custom chefctl.rb bundle from a tarball on Fedora:

{
  "steps": [
    {
      "type": "go2chef.step.install.linux.dnf",
      "name": "install chef",
      "version": "15.2.20-1.el7.x86_64",
      "source": {
        "type": "go2chef.source.http",
        "url": "https://packages.chef.io/files/stable/chef/15.2.20/el/8/chef-15.2.20-1.el7.x86_64.rpm"
      }
    },
    {
      "type": "go2chef.step.bundle",
      "name": "install chefctl",
      "source": {
        "type": "go2chef.source.local",
        "path": "./chefctl.tar.gz",
        "archive": true
      }
    }
  ]
}

Executing

  1. Copy the appropriate binary from build/$GOOS/$GOARCH/go2chef, the config file, and the chefctl bundle to a single directory on the target host

  2. Execute go2chef with the config

    $ cd path/to/copy
$ ./go2chef --local-config config.json

scripts/remote.go

A remote execution script is provided in scripts/remote.go. Example usage:

$ make windows && go run scripts/remote.go --binary build/windows/amd64/go2chef.exe -B examples/bundles/chefctl -B examples/bundles/chefrepo -B examples/bundles/whoami_exec --target 10.0.10.187 -W -c examples/config_install_msi.json

Design

go2chef has four basic building blocks, all of which are implemented using a plugin model:

  • Configuration Sources (go2chef.ConfigSource): fetch go2chef configuration from remote sources
  • Loggers (go2chef.Logger): send log messages and structured events to logging backends via a common plugin API
  • Steps (go2chef.Step): implement the building blocks of a go2chef workflow. Every action that needs to be taken to set up your Chef environment can be integrated into a go2chef step. See "Steps" for more details
  • Sources (go2chef.Source): implement a common API for retrieval of remote resources needed for Step execution

Configuration Sources

Configuration sources are the plugins which allow you to customize how go2chef retrieves its runtime configuration. We provide a couple configuration plugins out-of-the-box:

  • go2chef.config_source.local: loads configuration from a JSON file accessible on the filesystem. (this is the default configuration source)
  • go2chef.config_source.http: loads configuration source in JSON format from an HTTP(S) endpoint. Enable using go2chef --config-source go2chef.config_source.http
  • go2chef.config_source.embed: loads configuration source from an embedded variable. This probably isn't what you want, but if it is, have it.

New configuration sources can be registered with go2chef.RegisterConfigSource.

Loggers

Loggers are the plugins which allow go2chef users to report run information for monitoring and analysis, and provide plugin authors with a single API for logging and events.

For Users

Logging plugins are configured using the loggers key in go2chef configuration. An example configuration setting up the default go2chef.logger.stdlib looks like:

{
  "loggers": [
    {
      "type": "go2chef.logger.stdlib",
      "name": "stdlib",
      "level": "DEBUG",
      "debugging": 1,
      "verbosity": 1
    }
  ]
}

The loggers key is an array so that you can log to multiple places, which may be useful for the following scenarios:

  1. You want your raw log messages to go to syslog, but you also want to send specific events to a separate logging service using a custom plugin to trigger some downstream action (i.e. changing asset service state).
  2. You want to log to file and stderr and syslog at varying levels of verbosity (and so on and so forth)

For Developers

Logging plugins may skip parts of the interface specification by stubbing out the unneeded methods as no-ops.

The go2chef.MultiLogger implementation synchronously dumps messages out to backends at the moment, so delays in message sending in a Logger plugin may slow down execution of go2chef as well.

Steps

Steps are the plugins which actually "do stuff" in go2chef. These can do pretty much anything you want if you implement it, but we've intentionally limited the built-in plugins to the following initially:

  • Sanity checking: make sure that the runtime environment is sane before trying to install Chef -- are we root? Is the clock set right? Is there disk space?
  • Bundle exec: provide a simple abstraction for fetching and running some arbitrary scripts/binaries before/after installation. Do things like set up required certs, install chefctl.rb, etc.
  • Installers: provide installer implementations for each platform (and sub-platforms thereof, if necessary).

Many Step implementations will require some sort of remote resource retrieval; rather than leaving it up to each implementation to bring its own support code for downloads, we provide it to you using Sources (described next).

Sources

Source plugins implement a common API for resource retrieval for go2chef. This allows all steps to configure remote resource retrieval with the same idiom:

{
  "steps": [
    {
      "type": "go2chef.step.install.linux.apt",
      "name": "install chef",
      "source": {
        "type": "go2chef.source.http",
        "url": "https://example.com/chef-15.deb"
      }
    }
  ]
}

A source key inside a step configuration block defines how the remote resources for that step should be retrieved.

Code Layout

bin/        # go2chef binary source code
build/      # temporary directory for build outputs
cli/        # CLI implementation
plugin/     # plugins directory
  config/   # configuration source plugins
  logger/   # logger plugins
  source/   # source plugins
  step/     # step plugins
*.go        # go code for the base go2chef module

Contribute

See the CONTRIBUTING file for how to help out.

License

go2chef is Apache 2.0 licensed.