sctl 2020.0.4

A simple development environment manager.

space-control

space-control, or sctl, is a simple CLI tool for working within a distributed environment. The goal is to allow batch operations to be easily executed on any number of hosts, whether that means executing commands, downloading or uploading files, or whatever else is needed.

Sample configuration file:

directory: /
nodes:
  - host: 'some_host'
    user: 'root'
    connect_kwargs: {
      password: password
    }
  - host: 'mypi'
    user: 'pi'

sctl by default will look for a configuration file relative to your current location: .sctl/config.yml. If a file cannot be found, it will look in ~/.sctl/config.yml. Alternatively you can specify a path to a configuration using the -c / --configuration option. This will be expanded on in the future to allow for multiple "profiles" in a single config.

The keys for each entry of nodes are the parameters specified by fabric.connection.Connection (of the wonderful fabric) library. Any configuration you want to do locally with SSH keys, authorized_keys, etc. is up to you. If you are not familiar (as I was merely 10 hours ago) fabric is an awesome wrapper around paramiko and some other tools, and it is so easy and clean to use. Check out both of those libraries.

This tool is not complete and is far from it.

Install

Install via pip:

pip install sctl

Or for latest and greatest, clone this repository and then run:

python setup.py install

or install directly from GitHub with pip:

python -m pip install git+https://github.com/Lnk2past/space-control.git

Sample Usage

Run ls on each node and print the output (the default action is exec and may be omitted):

sctl ls

sctl exec ls

Download the .bashrc from each node:

sctl download .bashrc

Upload a new .bashrc to each node:

sctl upload .bashrc

Notes

You may omit specifying a directory in your configuration; in these cases the default directory is usually the home directory of the user you are logging in as.

Configurable Actions

space-control refers to executing commands and transferring files as actions. While you can certainly specify actions directly on the CLI (as shown above), you can also provide custom sets of actions in your configuration file. The added benefit here is that configurable actions are designed to allow you to chain multiple actions together (something you cannot do directly with the CLI). So for example, you can upload a file, run a command to produce a new file, and download that new file all by configuring a single set of actions.

nodes:
  - host: 'somehost'
    user: 'root'
actions:
  pgdump:
    - action: 'exec'
      command: 'docker exec postgres pg_dump -f pg_data.txt -t my_table my_db'
    - action: 'exec'
      command: 'docker cp postgres:pg_data.txt pg_data.txt'
    - action: 'download'
      remote: 'pg_data.txt'

The custom action pgdump here will execute pg_dump within the postgres container, copy the file from the postgres container, and then download it locally.

Filtering Nodes

Sometimes you may want to run an action on specific nodes in your configuration. This can be done using the -n / --nodes input options. This option takes a regex pattern and will filter nodes on that pattern. For example, given the following config:

nodes:
  - host: 'foo'
    user: 'root'
  - host: 'bar'
    user: 'root'
  - host: 'foobar'
    user: 'root'

We can run an action against the foo and foobar nodes only using:

sctl -n foo ls

Here the pattern foo will be partial matches for both foo and foobar and will both be included in the set of nodes to run against.