Crit

Infrastructure as actual code

Why?

This project is created as an alternative for applications like ansible or SaltStack. I ran into the problem of not being able to use actual code many times. So instead of using jinja2 to do conditionals you can actually use if and else

This project is also more focussed on developers that want to transition to devops activities

Getting started

We recommend using the crit-boilerplate

If you don't want to use the boilerplate we strongly advise to use vagrant for managing your servers.

Requirements

The only requirement for crit is that you have python 3.6 installed

Installing

pip install crit

You need two files to start using crit.

Config file

The config file contains all the config for crit. This is an example of this config file:

from crit.config import Host, GeneralConfig

server1 = Host(url='192.168.200.101', ssh_user='vagrant')

config = GeneralConfig(
    hosts=[
        server1
    ]
)

• hosts: This variable contains all the hosts you may use for your crit application

Sequence file

The sequence file contains a sequence of executors crit will run. This is an example of a sequence file:

from crit.executors import CommandExecutor
from crit.sequences import Sequence
from example.config import server1

sequence = Sequence(
      executors=[
          CommandExecutor(
              hosts=server1,
              command='ls -a'
          )
      ]
)

The sequence variable is mandatory for crit to work.

Running crit

Now you can run crit by using the crit command crit sequence.py

The first parameter is the path to the sequence script but crit also has some other parameters:

Short	Long	Default	Description	Example
-h	--hosts	all	The hosts on which the sequence will run	localhost
-c	--config	config.py	The path to the config file of crit	config/prod.py
-t	--tags	''	Comma separated string with the tags which filters which executors will run	tag1,tag2
-st	--skip-tags	''	Comma separated string with the tags the sequence will skip	tag3,tag4
-e	--extra-vars	''	Key value based variable that will be inserted into the registry	'key=value key2=value2'
-p	--linux-pass	''	Crit will ask for the linux password for the user that is used for ssh'ing	-p
-v	--verbose	0	Declares the debug level based on how many v's are given	-v or -vv or -vvv ect.

Verbosity

• 1: Prints the command ran
• 2: Prints the output & the results of multi executors
• 3: Shows what is skipped

Executors

What is an executor

An executor is a class that contains a command that will run on the server. Your crit config will all be based on executors.

Executors

Crit comes with some default executors

Name	Description	Doc url
Abstract Executors
BaseExecutor	The abstract class every executor should inherit. This will often be done by inheriting SingleExecutor or MultiExecutor	link
SingleExecutor	If the executor has a main single command. This is the class that will be inherited	link
MultiExecutor	If an executor relies on multiple single executors you can use a multi executor to run all the executors	link
Util executors
CommandExecutor	Executes a command on a server	link
AptExecutor	Installs package via apt-get	link
UserExecutor	Creates a linux user	link
FileExecutor	Creates a file or directory based on the status	link
Templa``teExecutor	Creates a file on the host based on a template	link
Docker Executors
DockerInstallExecutor	Installs docker as a service	link
DockerBuildExecutor	Build a docker container	link
DockerRunExecutor	Run a docker container	link
DockerPullExecutor	Pulls a docker image	link
DockerPushExecutor	Pushes a docker image to a registry	link
DockerTagExecutor	Tags a docker container	link
Git Executors
GitExecutor	Runs git clone -> git checkout -> git pull for one repository	link
GitCloneExecutor	Clones a repository	link
GitCheckoutExecutor	Checks out a certain git branch	link
GitPullExecutor	Pulls the changes to the repository	link

All executors can be found in the namespace crit.executors

Creating a custom executor

You can create a standard executor by initiating it. Below is an example of the CommandExecutor

CommandExecutor(command='ls -a')

As you can see this is very limited. This is why you can extend the BaseExecutor to create a totally customizable executor. This is an example how the CommandExecutor is written:

from dataclasses import dataclass
from crit.executors import SingleExecutor


@dataclass
class CommandExecutor(SingleExecutor):
    command: str = None

    def commands(self) -> str:
        return self.command

All the attributes of a custom executor that is also a @dataclass need to have a default value

Registry

As mentioned above the config of crit is loaded from a python file. But that is not the only config that crit handles.

Crit supplies a config module that has one especially interesting attribute. This is the registry attribute. This attribute is a dict that contains variables that can be used for conditionals in your executor! Each host has it's own registry. So you could access the localhost registry like this config.registry(repr(Localhost())['registry_key']

You can import the config via from crit.config import config

Status

Planning

Tests

We have unit tests and integration tests

Unit tests

You run them with this command coverage run -m unittest discover

Integration tests

You can run all tests by running cd /vagrant && sudo python3 setup.py install && cd /vagrant/tests/integration && sh test.sh

For more info on what is happening see below:

First install crit latest:

cd /vagrant && sudo python setup.py install

Everything of integration tests is in /tests/integration/ thus:

cd /vagrant/tests/integration

1. Install local packages: crit sequences/local_setup.py -vvv
2. Setup service server: crit sequences/service_server.py -vvv
3. Setup normal server: crit sequences/server_setup.py -h 192.168.200.102 -vvv
4. Deploy project: crit sequences/deploy_project.py -h 192.168.200.102 -vvv

Docs

The url to the docs are:

To build the docs:

export SPHINX_APIDOC_OPTIONS=members,show-inheritance && sphinx-apidoc -o docs crit -f -e && cp README.md docs/install.md && sphinx-build -b html docs docs/_build

Deployment

Ask Jessie Liauw A Fong to for deployment

Authors

• Jessie Liauw A Fong