Task - Simple task runner / "Make" alternative

Task is a simple tool that allows you to easily run development and build tasks. Task is written in Golang, but can be used to develop any language. It aims to be simpler and easier to use then GNU Make.

• Installation
• Usage
  • Environment
  • OS specific task
  • Task directory
  • Task dependencies
  • Calling another task
  • Prevent unnecessary work
  • Variables
    • Dynamic variables
  • Go's template engine
  • Help
  • Watch tasks
• Alternative task runners

Installation

If you have a Golang environment setup, you can simply run:

go get -u -v github.com/go-task/task/cmd/task

Or you can download the binary from the releases page and add to your PATH. DEB and RPM packages are also available.

Usage

Create a file called Taskfile.yml in the root of the project. The cmds attribute should contains the commands of a task:

build:
  cmds:
    - go build -v -i main.go

assets:
  cmds:
    - gulp

Running the tasks is as simple as running:

task assets build

Task uses github.com/mvdan/sh, a native Go sh interpreter. So you can write sh/bash commands and it will work even on Windows, where sh or bash is usually not available. Just remember any executable called must be available by the OS or in PATH.

If you ommit a task name, "default" will be assumed.

Environment

You can specify environment variables that are added when running a command:

build:
  cmds:
    - echo $hallo
  env:
    hallo: welt

OS specific task

If you add a Taskfile_{{GOOS}} you can override or amend your taskfile based on the operating system.

Example:

Taskfile.yml:

build:
  cmds:
    - echo "default"

Taskfile_linux.yml:

build:
  cmds:
    - echo "linux"

Will print out linux and not default

Task directory

By default, tasks will be executed in the directory where the Taskfile is located. But you can easily make the task run in another folder informing dir:

js:
  dir: www/public/js
  cmds:
    - gulp

Task dependencies

You may have tasks that depends on others. Just pointing them on deps will make them run automatically before running the parent task:

build:
  deps: [assets]
  cmds:
    - go build -v -i main.go

assets:
  cmds:
    - gulp

In the above example, assets will always run right before build if you run task build.

A task can have only dependencies and no commands to group tasks together:

assets:
  deps: [js, css]

js:
  cmds:
    - npm run buildjs

css:
  cmds:
    - npm run buildcss

If there are more than one dependency, they always run in parallel for better performance.

Each task can only be run once. If it is included from another dependend task causing a cyclomatic dependency, execution will be stopped.

task1:
  deps: [task2]

task2:
  deps: [task1]

The above will fail with the message: "cyclic dependency detected".

Calling another task

When a task has many dependencies, they are executed concurrently. This will often result in a faster build pipeline. But in some situations you may need to call other tasks serially. In this case, just use the following syntax:

main-task:
  cmds:
    - task: task-to-be-called
    - task: another-task
    - echo "Both done"

task-to-be-called:
  cmds:
    - echo "Task to be called"

another-task:
  cmds:
    - echo "Another task"

Overriding variables in the called task is as simple as informing vars attribute:

main-task:
  cmds:
    - task: write-file
      vars: {FILE: "hello.txt", CONTENT: "Hello!"}
    - task: write-file
      vars: {FILE: "world.txt", CONTENT: "World!"}

write-file:
  cmds:
    - echo "{{.CONTENT}}" > {{.FILE}}

The above syntax is also supported in deps.

NOTE: It's also possible to call a task without any param prefixing it with ^, but this syntax is deprecaded:

a-task:
  cmds:
    - ^another-task

another-task:
  cmds:
    - echo "Another task"

Prevent unnecessary work

If a task generates something, you can inform Task the source and generated files, so Task will prevent to run them if not necessary.

build:
  deps: [js, css]
  cmds:
    - go build -v -i main.go

js:
  cmds:
    - npm run buildjs
  sources:
    - js/src/**/*.js
  generates:
    - public/bundle.js

css:
  cmds:
    - npm run buildcss
  sources:
    - css/src/*.css
  generates:
    - public/bundle.css

sources and generates should be file patterns. When both are given, Task will compare the modification date/time of the files to determine if it's necessary to run the task. If not, it will just print Task "js" is up to date.

Alternatively, you can inform a sequence of tests as status. If no error is returned (exit status 0), the task is considered up-to-date:

generate-files:
  cmds:
    - mkdir directory
    - touch directory/file1.txt
    - touch directory/file2.txt
  # test existence of files
  status:
    - test -d directory
    - test -f directory/file1.txt
    - test -f directory/file2.txt

You can use --force or -f if you want to force a task to run even when up-to-date.

Variables

When doing interpolation of variables, Task will look for the below. They are listed below in order of importance (e.g. most important first):

• Variables given while calling a task from another. (See Calling another task above)
• Environment variables
• Variables declared locally in the task
• Variables available in the Taskvars.yml file

Example of overriding with environment variables:

$ TASK_VARIABLE=a-value task do-something

Example of locally declared vars:

print-var:
  cmds:
    echo "{{.VAR}}"
  vars:
    VAR: Hello!

Example of Taskvars.yml file:

PROJECT_NAME: My Project
DEV_MODE: production
GIT_COMMIT: $git log -n 1 --format=%h

NOTE: It's also possible setting a variable globally using set attribute in task, but this is deprecated:

build:
  deps: [set-message]
  cmds:
    - echo "Message: {{.MESSAGE}}"

set-message:
  cmds:
    - echo "This is an important message"
  set: MESSAGE

Dynamic variables

If you prefix a variable with $, then the variable is considered a dynamic variable. The value after the $-symbol will be treated as a command and the output assigned.

build:
  cmds:
    - go build -ldflags="-X main.Version={{.LAST_GIT_COMMIT}}" main.go
  vars:
    LAST_GIT_COMMIT: $git log -n 1 --format=%h

This works for all types of variables.

Go's template engine

Task parse commands as Go's template engine before executing them. Variables are acessible through dot syntax (.VARNAME).

All functions by the Go's sprig lib are available. The following example gets the current date in a given format:

print-date:
  cmds:
    - echo {{now | date "2006-01-02"}}

Task also adds the following functions:

• OS: Returns operating system. Possible values are "windows", "linux", "darwin" (macOS) and "freebsd".
• ARCH: return the architecture Task was compiled to: "386", "amd64", "arm" or "s390x".
• ToSlash: Does nothing on Unix, but on Windows converts a string from \ path format to /.
• FromSlash: Oposite of ToSlash. Does nothing on Unix, but on Windows converts a string from \ path format to /.
• ExeExt: Returns the right executable extension for the current OS (".exe" for Windows, "" for others).

Example:

print-os:
  cmds:
    - echo '{{OS}} {{ARCH}}'
    - echo '{{if eq OS "windows"}}windows-command{{else}}unix-command{{end}}'
    # This will be path/to/file on Unix but path\to\file on Windows
    - echo '{{FromSlash "path/to/file"}}'

Help

Running task help lists all tasks with a description. The following taskfile:

build:
  desc: Build the go binary.
  cmds:
    - go build -v -i main.go

test:
  desc: Run all the go tests.
  cmds:
    - go test -race ./...

js:
  cmds:
    - npm run buildjs

css:
  cmds:
    - npm run buildcss

would print the following output:

build   Build the go binary.
test    Run all the go tests.

Watch tasks (experimental)

If you give a --watch or -w argument, task will watch for files changes and run the task again. This requires the sources attribute to be given, so task know which files to watch.

Alternative task runners

• YAML based:
  • tj/robo
  • dogtools/dog
  • goeuro/myke
• Go based:
  • go-godo
  • markbates/grift