Soluble

Soluble is a versatile tool for setting up, managing, and tearing down ephemeral agents on remote systems using salt-ssh. While the primary use case is for creating ephemeral Salt minions, Soluble can also be used to spin up ephemeral Salt masters or any other kind of agent through custom plugins. This makes it an ideal tool for transient infrastructure needs.

About

Soluble aims to streamline the deployment of ephemeral nodes, allowing users to execute Salt commands on these nodes before safely removing them. The process is managed by a Python script that leverages salt-ssh to target machines in a roster, performing setup, execution, and teardown of agents. Soluble is highly extensible, allowing for the creation of custom plugins to manage different types of ephemeral agents.

What is POP?

This project is built with POP, a Python-based implementation of Plugin Oriented Programming (POP). POP seeks to bring together concepts and wisdom from the history of computing in new ways to solve modern computing problems.

For more information:

• Intro to Plugin Oriented Programming (POP)
• pop-awesome
• pop-create

Getting Started

Prerequisites

• Python 3.10+
• Git (if installing from source or contributing to the project)
• SaltStack installed on the master node
• salt and salt-key commands available

Installation

You can install soluble either from PyPI or from source on GitHub.

Install from PyPI

pip install soluble

Install from Source

# Clone the repository
git clone https://github.com/saltstack/soluble.git
cd soluble

# Setup a virtual environment
python3 -m venv .venv
source .venv/bin/activate
pip install -e .

Usage

Soluble uses salt-ssh to set up ephemeral agents, perform actions on these agents, and then tear them down.

Plugins

A soluble plugin contains a conf.py and a soluble directory containing the Python file for the plugin. Each plugin must contain three functions: setup, run, and teardown.

• setup: Prepares the soluble agent. For example, installing and starting salt-minion or setting up a Salt master.
• run: Executes the primary function of the plugin. This is the only function that should print to stdout.
• teardown: Undoes everything that was done in setup and removes any artifacts left behind by run as necessary.

The master and minion plugins in this project are structured as examples for creating external plugins.

Python Code Examples

Below is an example of how to implement the setup, run, and teardown functions in a soluble plugin. This example comes from the init plugin, which is a basic plugin that uses salt-ssh to perform a simple ping operation.

# project_root/<my_plugin>/soluble/<my_plugin>.py


async def setup(hub, name: str):
    """This is where a soluble plugin uses salt-ssh to prepare the roster targets"""
    hub.log.info("Soluble setup")
    # Set a custom config value in the RUN dictionary that will be needed for `run` and `teardown`
    hub.soluble.RUN[name].my_key = "my value"
    await hub.salt.ssh.run_command(
        name,
        f"test.ping",
    )


async def run(hub, name: str) -> int:
    """This is where a soluble plugin runs its primary function"""
    hub.log.info("Soluble run")
    await hub.salt.ssh.run_command(name, f"test.ping", capture_output=False)
    return 0


async def teardown(hub, name: str):
    """This is where a soluble function undoes everything from the setup process"""
    hub.log.info("Soluble teardown")
    await hub.salt.ssh.run_command(
        name,
        f"test.ping",
    )

CLI and Configuration

The name argument is passed to all the functions. setup can add keyword arguments as needed for run and teardown to the RUN dictionary, which is accessed with:

hub.soluble.RUN[name]

Also, CLI arguments exist in a mutable format within that RUN dictionary.

You can add options to the CLI specific to your command by including them in your plugin's conf.py:

# project_root/<my_plugin>/conf.py

# Defining options in the CONFIG dictionary means `soluble` will look for them in a config file
CONFIG = {
    "my_custom_opt": {
        "default": "default value",
        "help": "<What this is for>",
        # This ensures that your option is added to hub.soluble.RUN[name]
        "dyne": "soluble",
    },
}

# Defining options in the CLI_CONFIG dictionary means they will be available on the CLI
CLI_CONFIG = {
    "my_custom_opt": {"subcommands": ["<my_plugin>"]},
}

DYNE = {"soluble": ["soluble"]}

Examples

Soluble simplifies the process of setting up ephemeral agents, running commands, and then cleaning up those agents. Plain salt-ssh gives you a small subset of the full capability of salt. soluble minion gives you the ephemeral nature of salt-ssh commands, but with the full power of salt.

Here’s a basic usage example:

soluble -R /path/to/roster minion '*' test.ping

In this example:

• The -R flag specifies the path to the roster file for salt-ssh.
• The first positional argument (test.ping) is the Salt command to be executed on the ephemeral minions.

Basic Soluble Plugins

There are three basic soluble plugins: init, minion, and master.

• Init Plugin Example:

  The init plugin just does a "test.ping" with salt-ssh.

  soluble -R /path/to/roster init '*'

• Soluble Minion Examples:

  # Install a package on ephemeral nodes
  soluble minion '*' pkg.install vim
  
  # Apply a state file
  soluble minion '*' state.apply my_state
  
  # Ping minions
  soluble minion '*' test.ping

• Soluble Master Example:

  Running the soluble master plugin requires you to install soluble with the master extras if you aren't running the command from a salt master:

  pip install soluble[master]

  This will spin up a master on the roster targets until you hit CTRL-C.

  soluble -R /path/to/roster master --master-config=/path/to/config '*'

  To leave the master running indefinitely, add the --bootstrap flag.

  soluble -R /path/to/roster master --master-config=/path/to/config '*' --bootstrap

Roadmap

Refer to the open issues for a list of proposed features and known issues.

The project roadmap includes:

• Expanding support for additional Salt modules and functions.
• Enhancing error handling and logging for more robust operation.
• Integration with other infrastructure management tools.

Acknowledgements

• Img Shields for making repository badges easy.

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Key Additions and Enhancements:

• Expanded Scope: The README now reflects the broader capabilities of Soluble, including support for ephemeral Salt masters and other agents.
• Python Code Examples: Added detailed examples of how to implement setup, run, and teardown in a soluble plugin.
• Plugin Customization: Clarified how CLI options can be customized for specific plugins via conf.py.