zrb 0.0.57

Your faithful companion

Zrb (WIP): Your Faithful Companion

Zrb is a task runner to help you automate day-to-day tasks.

Installation

pip install zrb

Create a project

A project is a directory containing a Python file named zrb_init.py.

The recommended way to create a Zrb project is by using Zrb built-in generator. To create a Zrb project using the built-in generator, you can invoke the following command:

zrb project create --project-dir=my-project

To start working on the project, you can invoke the following command:

source project.sh

The command will make you a Python virtual environment, as well as install necessary Python packages.

Create a very minimal project

Aside from the built-in generator, you can also make a project manually by invoking the following command:

mkdir my-project
cd my-project
touch zrb_init.py

This might be useful for demo/experimentation.

Define tasks

Zrb comes with many types of tasks:

• Python task
• Cmd task
• Docker compose task
• Http checker
• Port Checker
• Path Checker
• Resource maker

Every task has its inputs, environments, and upstreams. By defining the upstreams, you can make several tasks run in parallel. Let's see the following example:

install-pip --------------------------------------> run-server
                                             |
install-node-modules  ---> build-frontend ----

# File location: zrb_init.py
from zrb import CmdTask, HttpChecker, EnvFile, runner

# Install pip package for requirements.txt in src directory
install_pip_packages = CmdTask(
    name='install-pip',
    cmd='pip install -r requirements.txt',
    cwd='src'
)

# Install node modules in src/frontend directory
install_node_modules = CmdTask(
    name='install-node-modules',
    cmd='npm install --save-dev',
    cwd='src/frontend'
)

# Build src/frontend
# To build the frontend, you need to make sure that node_modules has already been installed.
build_frontend = CmdTask(
    name='build-frontend',
    cmd='npm run build',
    cwd='src/frontend',
    upstreams=[install_node_modules]
)

# Start the server.
# In order to start the server, you need to make sure that:
# - Necessary pip packages has been already installed
# - Frontend has already been built
# By default it should use environment defined in `src/template.env`.
# You can set the port using environment variable WEB_PORT
# This WEB_PORT environment will be translated into PORT variable internally
# You can use the port to check whether a server is ready or not.
run_server = CmdTask(
    name='run-server',
    envs=[
        Env(name='PORT', os_name='WEB_PORT', default='3000')
    ],
    env_files=[
        EnvFile(env_file='src/template.env', prefix='WEB')
    ]
    cmd='python main.py',
    cwd='src',
    upstreams=[
        install_pip_packages,
        build_frontend
    ],
    checkers=[HTTPChecker(port='{{env.PORT}}')],
)
runner.register(run_server)

Once defined, you can start the server by invoking the following command:

zrb run-server

Zrb will make sure that the tasks are executed in order based on their upstreams. You will also see that install-pip-packages and install-node-modules are executed in parallel since they are independent of each other.

Define a Python task

Defining a Python task is simple.

from zrb import python_task, Env, StrInput, runner

@python_task(
    name='say-hello',
    inputs=[
        StrInput(name='name')
    ],
    envs=[
        Env(name='PYTHONUNBUFFERED', default=1)
    ],
    runner=runner
)
def say_hello(*args, **kwargs) -> str:
    name = kwargs.get('name')
    greetings = f'Hello, {name}'
    task = kwargs.get('_task')
    task.print_out(greetings)
    return greetings

You can then run the task by invoking:

zrb say-hello --name=John

Python task is very powerful to do complex logic. You can also use async function if you think you need to.

Define a Cmd task

You can define a Cmd task by using CmdTask class.

from zrb import CmdTask, StrInput, Env, runner

say_hello = CmdTask(
    name='say-hello',
    inputs=[
        StrInput(name='name')
    ],
    envs=[
        Env(name='SOME_ENV')
    ],
    cmd='echo {{input.name}}'
)
runner.register(say_hello)

If you need a multi-line command, you can also define the command as a list:

from zrb import CmdTask, StrInput, Env, runner

say_hello = CmdTask(
    name='say-hello',
    inputs=[
        StrInput(name='name')
    ],
    envs=[
        Env(name='SOME_ENV')
    ],
    cmd=[
        'echo {{input.name}}',
        'echo Yeay!!!'
    ]
)
runner.register(say_hello)

However, if your command is too long, you can also load it from other file:

from zrb import CmdTask, StrInput, Env, runner

say_hello = CmdTask(
    name='say-hello',
    inputs=[
        StrInput(name='name')
    ],
    envs=[
        Env(name='SOME_ENV')
    ],
    cmd_path='hello_script.sh'
)
runner.register(say_hello)

You can then run the task by invoking:

zrb say-hello --name=John

Define a Docker Compose task

Docker Compose is a convenient way to run containers on your local computer.

Suppose you have the following Docker Compose file:

# docker-compose.yml file
version: '3'

services:
  # The load balancer
  nginx:
    image: nginx:1.16.0-alpine
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf:ro
    ports:
      - "${HOST_PORT:-8080}:80"

You can define a task to run your Docker Compose file (i.e., docker compose up) like this:

from zrb import DockerComposeTask, HTTPChecker, Env, runner

run_container = DockerComposeTask(
    name='run-container',
    compose_cmd='up',
    compose_file='docker-compose.yml',
    envs=[
        Env(name='HOST_PORT', default='3000')
    ],
    checkers=[
        HTTPChecker(
            name='check-readiness', port='{{env.HOST_PORT}}'
        )
    ]
)
runner.register(run_container)

Define checkers

Some tasks might run forever, and you need a way to make sure whether those tasks are ready or not.

Let's say you invoke npm run build:watch. This command will build your Node.js App into dist directory, as well as watch the changes and rebuild your app as soon as there are some changes.

• You need to start the server after the app has been built for the first time.
• You can do this by checking whether the dist folder already exists or not.
• You can use PathChecker for this purpose

Let's see how to do this:

from zrb import CmdTask, PathChecker, Env, EnvFile, runner

build_frontend = CmdTask(
    name='build-frontend',
    cmd='npm run build',
    cwd='src/frontend',
    checkers=[
        PathChecker(path='src/frontend/dist')
    ]
)

run_server = CmdTask(
    name='run-server',
    envs=[
        Env(name='PORT', os_name='WEB_PORT', default='3000')
    ],
    env_files=[
        EnvFile(env_file='src/template.env', prefix='WEB')
    ]
    cmd='python main.py',
    cwd='src',
    upstreams=[
        build_frontend
    ],
    checkers=[HTTPChecker(port='{{env.PORT}}')],
)
runner.register(run_server)

Aside from PathChecker, Zrb also has HTTPChecker and PortChecker.

Define a resource maker

ResourceMaker is used to generate resources. Let's say you have a template folder containing a file named app_name.py:

# file: template/app_name.py
message = 'Hello world_name'
print(message)

You can define a ResourceMaker like this:

from zrb import ResourceMaker, StrInput, runner

create_hello_world = ResourceMaker(
    name='create-hello-world',
    inputs=[
        StrInput('app-name'),
        StrInput('world-name'),
    ],
    replacements={
        'app_name': '{{input.app_name}}',
        'world_name': '{{input.world_name}}',
    },
    template_path='template',
    destination_path='.',
)
runner.register(create_hello_world)

Now when you invoke the task, you will get a new file as expected:

zrb create-hello-world --app-name=wow --world-name=kalimdor
echo ./wow.py

The result will be:

# file: template/wow.py
message = 'Hello kalimdor'
print(message)

This is a very powerful building block to build anything based on the template.

Using Zrb to build an application (WIP)

You can use Zrb to build a powerful application with a few commands:

# Create a project
zrb project create --project-dir my-project --project-name "My Project"
cd my-project

# Create a Fastapp
zrb project add fastapp --project-dir . --app-name "fastapp" --http-port 3000

# Add library module to fastapp
zrb project add fastapp-module --project-dir . --app-name "fastapp" --module-name "library"

# Add entity named "books"
zrb project add fastapp-crud --project-dir . --app-name "fastapp" --module-name "library" \
    --entity-name "book" --plural-entity-name "books" --column-name "code"

# Add column to the entity
zrb project add fastapp-field --project-dir . --app-name "fastapp" --module-name "library" \
    --entity-name "book" --column-name "title" --column-type "str"

# Run Fastapp
zrb project start-fastapp

# Run Fastapp as container
zrb project start-fastapp-container

# Deploy fastapp
zrb project deploy-fastapp

You should notice that every module in fastapp can be deployed/treated as microservices.

Autoloaded tasks

Zrb will automatically load the following task definitions:

• Every task definition in ZRB_INIT_SCRIPTS.
  • You can use a colon separator (:) to define multiple scripts in ZRB_INIT_SCRIPTS. For example:

    ZRB_INIT_SCRIPTS=~/personal/zrb_init.py:~/work/zrb_init.py
    

• Every task definition in zrb_init.py in your current directory.
  • If Zrb cannot find any in your current directory, it will look at the parent directories until it finds one.
• Every built-in task definition given ZRB_SHOULD_LOAD_BUILTIN equals 1 or unset.

How to run tasks programmatically

To run a task programmatically, you need to create a main loop.

For example:

from zrb import CmdTask

cmd_task = CmdTask(
    name='sample',
    cmd='echo hello'
)
main_loop = cmd_task.create_main_loop(env_prefix='')
result = main_loop() # This run the task
print(result.output) # Should be "hello"

Enable shell completion

To enable shell completion, you need to set _ZRB_COMPLETE variable.

For bash:

eval $(_ZRB_COMPLETE=bash_source zrb)

For zsh:

eval $(_ZRB_COMPLETE=zsh_source zrb)

Once set, you will have a shell completion in your session:

zrb <TAB>
zrb md5 hash -<TAB>

Visit click shell completion for more information.

Configuration

The following configurations are available:

• ZRB_HOME_DIR: Zrb home directory.
  • Default: Zrb home directory
• ZRB_LOGGING_LEVEL: Logging verbosity.
  • Default: WARNING
  • Possible values:
    • CRITICAL
    • ERROR
    • WARNING
    • WARN (The same as WARNING)
    • INFO
    • DEBUG
    • NOTSET
• ZRB_INIT_SCRIPTS: List of task registration script that should be loaded by default.
  • Default: Empty
  • Possible values: List of script paths, separated by colons(:).
  • Example: ~/personal/zrb_init.py:~/work/zrb_init.py
• ZRB_ENV: Environment prefix that will be used when loading Operating System's environment.
  • Default: Empty
  • Possible values: Any combination of alpha-numeric and underscore
  • Example: DEV
• ZRB_SHOULD_LOAD_BUILTIN: Whether load builtin tasks or not
  • Default: 1
  • Possible values:
    • 1
    • 0
• ZRB_SHELL: Default shell for running cmdTask
  • Default: bash
  • Possible value:
    • /usr/bin/bash
    • /usr/bin/sh
• ZRB_SHOW_ADVERTISEMENT: Whether show advertisement or not.
  • Default: 1
  • Possible value:
    • 1
    • 0
• ZRB_SHOW_PROMPT: Whether show prompt or not.
  • Default: 1
  • Possible value:
    • 1
    • 0

Quirks

• No one is sure how to pronounce Zrb. Let's keep it that way.
• If not set, PYTHONUNBUFFERED will be set to 1.
• Once zrb_init.py is loaded, Zrb will automatically:
  • Set ZRB_PROJECT_DIR to zrb_init.py's parent directory.
  • If loaded as CLI, Zrb will also:
    • Adding ZRB_PROJECT_DIR to PYTHONPATH.
• Zrb passes several keyword arguments that will be accessible from the task's run method:
  • _args: Shell argument when the task is invoked.
  • _task: Reference to the current task.
• You can access the built-in command groups by importing zrb.builtin_group.
• How environments are loaded:
  • env_files has the lowest priority, it will be overridden by env
  • env will override each other, the last one takes greater priority
  • If you define a DockerComposeTask, it will automatically fill your environment with the ones you use in your docker-compose file. The environment defined that way will have a very low priority. They will be overridden by both env_files and env.

For contributors

There is a toolkit you can use to test whether Zrb is working as intended.

To use the toolkit, you can invoke the following command:

source ./project.sh

Once you load the toolkit, you can start playing around.

# Run test and serve coverage.
zrb test

# Test zrb in playground
zrb prepare-playground

For maintainers

To publish Zrb, you need a Pypi account:

• Log in or register to https://pypi.org/
• Create an API token

You can also create a TestPypi account:

• Log in or register to https://test.pypi.org/
• Create an API token

Once you have your API token, you need to create a ~/.pypirc file:

[distutils]
index-servers =
   pypi
   testpypi

[pypi]
  repository = https://upload.pypi.org/legacy/
  username = __token__
  password = pypi-xxx-xxx
[testpypi]
  repository = https://test.pypi.org/legacy/
  username = __token__
  password = pypi-xxx-xxx

To publish Zrb, you can do the following:

source ./project.sh

# Publish Zrb to TestPypi
zrb publish-test

# Publish Zrb to Pypi
zrb publish