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./task

Run any project.

---

The task file is a simple bash script and standardized interface for all software projects.

It is to be understood as a software development pattern to standardize the installation, configuration and execution of different software frameworks.

Specification

The specification is a short guide to set up a task file for a Python project.

• Create a file task in your project.

touch task

• Ensure it is executable.

chmod +x task

• First add the bash shebang.

#!/bin/bash

• Then append the abort on error setting.

set -e

• Load environment variables from the .env file.

if [[ -a ".env" ]]; then
    source .env
fi

• Add a help function.

function help-table() {
    CMD_WIDTH=10
    OPT_WIDTH=6
    DESC_WIDTH=40
    COLUMN="| %-${CMD_WIDTH}s | %-${OPT_WIDTH}s | %-${DESC_WIDTH}s |\n"
    printf "$COLUMN" "Command" "Option" "Description"
    echo "|$(printf '%*s' $((CMD_WIDTH + 2)) '' | tr ' ' '-')|$(printf '%*s' $((OPT_WIDTH + 2)) '' | tr ' ' '-')|$(printf '%*s' $((DESC_WIDTH + 2)) '' | tr ' ' '-')|"
    printf "$COLUMN" "all" "" "Run all tasks."
    printf "$COLUMN" "help" "[grep]" "Show help for commands."
    printf "$COLUMN" "install" "" "Setup the local environment."
    printf "$COLUMN" "lint" "" "Run pre-commit and update index.html."
    printf "$COLUMN" "version" "" "Show version of required tools."
}

function help() {
    echo
    if [ -n "$1" ]; then
        help-table | grep -i "$1" | column -t -s'|'
    else
        echo "task <command> [options]"
        echo
        echo "commands:"
        echo
        help-table
    fi
    echo
}

• Setup the command functions.

function version() {
    uv --version
}

function install() {
    echo "Setup venv and install python dependencies"
    uv venv env
    source env/bin/activate
    uv pip install pre-commit
}

function lint() {
    source env/bin/activate

    echo "Run pre-commit"
    pre-commit run --all-file
}

• Finish the task file with command switch cases.

if declare -f "$1" > /dev/null; then
    "$1" "${@:2}"
else
    case "$1" in
        all)
            install
            lint
            ;;
        *)
            echo "Unknown command: $1"
            help
            exit 1
            ;;
    esac
fi

These are the main parts of every task file script.

Usage

Running the task file requires a shell alias: alias task='./task'
Show the available commands with task help.
From the specification the project can be installed with task install.
Execute all commands with task all.

Image

See taskfile.build/image for details.

Naming

The naming of functions is important. There are basically two styles:

1. Action + Object
2. Object + Action

The task file functions use the first style. The name of the function starts with an action followed by an object. The object name can be singular or plural.

Examples for actions: activate, install, dev, develop, init, build, start, update, remove, delete, enable, disable, template, convert, create, edit, change, get, set, patch, fetch, generate, push, pull, import, export, list, publish, release, test, setup, prepare, restart, stop, store, restore, translate, upgrade, zip, visualize, sync, switch, run, reset, load, dump, checkout, commit, drop, deploy, handle, trigger, render, lint, uninstall, split, parse, fix, refactor, transform, cat, ls, rm, serve, help, show, filter, login, logout, encrypt, decrypt, upload, download, analyse, transpile, compile, minify, copy

Examples for objects: env, venv, submodule, container, database, snippet, model, module, repo, mail, doc, dependency, view, user, vault, file, host, node, log, password, hash, script, requirement, part, component, system, workspace, image, process, state, platform, dir, folder, readme, overview, lang, level, request, response, result, worker, server, proxy, workflow, volume, network, package, field, value, secret, chart, node, edge, function, method, firewall, html, css, image, svg, style, query, native, group, notebook

Objects can be tools: odoo, vupress, nodejs, zsh, bash, fish, podman, kind, minikube, helm, nvim, docker, podman, rust, python, tmux, vim, helix, system, git, pass, llm, sql, dotenv, javascript, vue, vite, astro, typescript, turbo, pnpm, eslint, jenkins, k8s, nextcloud, postgres, metabase, ansible, prometheus, grafana, hugo, deno, bun, babel, panda, gulp, grunt, electron, react, express, mongodb, angular, ionic, meteor, webpack, bower, jupyter

Generate Function Names

Patterns

The task file showed above is very basic. Commands can have parameters and call each other. The following is a collection of more complex task file patterns.

Set default parameter

Fallback to a default value for a parameter.

function build() {
    PLATFORM="amd64"
    if [ -n "$1" ]; then
        PLATFORM="$1"
    fi

Ensure parameter is not empty

Check the first param and exit if it is empty.

function deploy() {
    if test -z "$1"; then echo "\$1 is empty."; exit; fi

Prompt for input

Use read to ask for inputs.

if [ -z "$2" ]; then
	read -p "Enter the task description: " TASK_DESCRIPTION
else
	TASK_DESCRIPTION="$2"
fi

Setup local env vars

Define env vars at the beginning of the task file.

CONFIGURATION_FILE="file.conf"
GIT_BRANCH=$(git symbolic-ref --short -q HEAD)

Template with env vars

Create a parameterized file from a template. Requires envsubst.

function template-with-env() {
    echo "Template $CONFIGURATION_FILE"

    export CONFIGURATION_1
    export CONFIGURATION_2=${CONFIGURATION_2:="value"}

    envsubst < "file.conf.template" > "$CONFIGURATION_FILE"
}

Create Python virtual env

Initialize Python virtual env with uv.

function init-venv() {
    if [ ! -d "venv$GIT_BRANCH" ]; then
        echo "Init venv$GIT_BRANCH with $(uv --version)."
        uv venv "venv$GIT_BRANCH"
    fi
}

Activate Python virtual env

function activate-venv() {
    echo "Source virtualenv venv$GIT_BRANCH."
    source "venv$GIT_BRANCH/bin/activate"
    echo "$(python --version) is active."
}

Call a Python script

Run a Python script.

function generate-password-hash() {
    activate-venv
    if test -z "$1"; then echo "\$1 is empty."; exit; fi
    PASSWORD_PLAIN="$1"
    bin/password-hash
}

The Python script: bin/password-hash

#!/usr/bin/env python3

import os
from passlib.context import CryptContext
crypt_context = CryptContext(schemes=['pbkdf2_sha512', 'plaintext'], deprecated=['plaintext'])

password = os.environ.get('PASSWORD_PLAIN')
print(crypt_context.hash(password))

Command with named parameters

Assuming you have a docker-compose.yml and would like to start selected or all containers.

function start() {

    if [[ "$1" =~ "db" ]]; then
        docker compose up -d db
    fi

    if [[ "$1" =~ "admin" ]]; then
        docker compose up -d admin
        echo "Open http://localhost:8000 url in your browser."
    fi

    if [[ "$1" =~ "odoo" ]]; then
        docker compose up -d odoo
        echo "Open http://localhost:8069 url in your browser."
    fi

    if [[ "$1" =~ "mail" ]]; then
	    docker compose up -d mail
        echo "Open http://localhost:8025 url in your browser."
    fi
}

Start all containers with task start and selected with task start db,admin.

Run commands in container

Use docker exec -i to run commands in a container.

function drop-db() {
    DATABASE="$1"
    if [ -z "$DATABASE" ]; then
        DATABASE="example"
    fi

    docker exec -i db psql "postgres://odoo:odoo@localhost:5432/postgres" -c "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = '$DATABASE';"
    docker exec -i db psql "postgres://odoo:odoo@localhost:5432/postgres" -c "DROP DATABASE \"$DATABASE\";"
}

Loop over files and folders

Use for to loop over file, folders or arrays.

function render() {
    echo "Update index.html for all folders"
    for FOLDER in ./*; do
        if [ -f "$FOLDER/README.md" ]; then
            cd "$FOLDER" || exit
            md2html README.md _site/index.html
            cd .. || exit
        fi
    done
}

Parse and convert a file

With this function you can split a file into multiple parts whenever a specific keyword is matching. In this example the keyword is !vault.

function convert-vault-file() {
    FILE_PATH="$1"
    TEMP_FILE=$(mktemp)
    TEMP_PART_FILE=$(mktemp)
    WRITE_FINISHED=false
    CURRENT_KEY=""

    while IFS= read -r LINE; do
        # Check for keyword
        if [[ "$LINE" =~ "!vault" ]]; then
            # Process previous vault entry if it exists
            if [ "$WRITE_FINISHED" = true ] && [ -n "$CURRENT_KEY" ] && [ -s "$TEMP_PART_FILE" ]; then
                # Decrypt part file and write to assemble file
                ansible-vault decrypt "$TEMP_PART_FILE"
                VALUE=$(cat "$TEMP_PART_FILE")
                echo "$CURRENT_KEY: $VALUE" >> "$TEMP_FILE"
            fi

            # Set up for new vault entry
            CURRENT_KEY=$(echo "$LINE" | cut -d':' -f1)
            # Clear the file
            : > "$TEMP_PART_FILE"
            # Flag as ready to write
            WRITE_FINISHED=true
        else
            if [ "$WRITE_FINISHED" = true ]; then
                # Pipe into part file
                echo "$LINE" >> "$TEMP_PART_FILE"
            fi
        fi
    done < "$FILE_PATH"

    # Process the final vault entry
    if [ "$WRITE_FINISHED" = true ] && [ -n "$CURRENT_KEY" ] && [ -s "$TEMP_PART_FILE" ]; then
        ansible-vault decrypt "$TEMP_PART_FILE"
        VALUE=$(cat "$TEMP_PART_FILE")
        echo "$CURRENT_KEY: $VALUE" >> "$TEMP_FILE"
    fi

    # Output assembled file
    cat "$TEMP_FILE"
    # Cleanup temp files
    rm -f "$TEMP_FILE"
    rm -f "$TEMP_PART_FILE"
}

Process data

This pattern tries to match the worklow of a jupyter notebook. Create a folder with the data processing scripts:

scripts
├── 01_import-mail-data
├── 02_transform-mail-data
└── 03_export-mail-data

The following function lists the scripts and asks for the number of scripts to run. Every script until the entered number is concatenated and executed.

function process-data() {
    while true; do
        SCRIPTS=($(ls scripts))

        echo -e "Available scripts:\n"
        for INDEX in "${!SCRIPTS[@]}"; do
            echo "$((INDEX+1)): ${SCRIPTS[$INDEX]}"
        done
        echo ""
        read -p "Enter the number of scripts to run (or 'q' to quit): " USER_INPUT
        if [ "${USER_INPUT}" = "q" ]; then
            break
        fi