Please

Please is a cross-language build system with an emphasis on high performance, extensibility and reproducibility. It supports a number of popular languages and can automate nearly any aspect of your build process.

See http://please.build for more information.

Currently Linux (tested on Ubuntu), macOS and FreeBSD are actively supported.

If you're a fan of Please, don't forget to add yourself to the adopters file.

Getting Started

The easiest way to install it on your own machine is to run:

curl -s https://get.please.build | bash

Or, if you prefer, grab one of the tarballs off our releases page and extract it yourself; it typically lives in ~/.please.

You can also install using Homebrew:

brew tap thought-machine/please
brew install please

Then you simply run plz init at the root of your project to set up a default config and you're ready to go. The best way to get to grips with Please is through the codelabs! There's also the getting started guide that explains the core concepts.

How is it so fast?

Please has a robust and correct caching model that enables us to aggressively cache artifacts. Caching is based on the hashes of inputs (both files, and environment variables) to each rule rather than last modified timestamps. Builds are hermetic so don't have access to anything they haven't explicitly defined as inputs. This means that if anything changes, we know exactly what might've been affected, so the minimal set of targets get built and tested.

Because each task is hermetic, they can be run in parallel without any chance of interfering with each-other. Combine these two concepts with shared remote caches, and it makes for a blazing fast build system for any language or technology.

Please is also written in Go and every effort has been made to make it as fast as possible. There's no startup time waiting to bring up VMs, interpreting code or communicating with remote JVM processes. The code itself takes full advantage of Go's concurrency and asynchronicity. The end result is a snappy command line tool that gets to work immediately and feels great to use.

Why Please, and not Maven, pip, or go build?

A build system is more than just a mechanism for invoking the compiler. If you're working on just one language, don't have any code generation, and don't need to publish any artifacts anywhere, you might not need Please. Chances are this is not the case.

Building software often involves more than just compiling code. There's deployment config to template, code to generate, and quite often, there's more than one language involved. Please provides a powerful, comprehensive, and understandable framework that you can use to craft a truly holistic build process.

Please does this through a consistent and seamless command line interface; there's no need to learn new build systems and technologies for different languages. Build any target with plz build, test any target with plz test, no matter what's going on under the hood.

The Docker & Kubernetes codelab covers building a Kubernetes based application with Please, including reliably deploying code to a local cluster, and pushing it to a remote registry.

The genrule() codelab covers extending Please with custom build definitions to truly automate any part of your deployment process.

Why Please, and not make?

Make is a great tool for running tasks. It's easy enough to understand because it leaves you very close to the shell. The problem is, it has limited capability to build out complexity. There have been attempts to generate make files from higher level tools like cmake and ninja, but they fall short of what Please sets out to achieve.

The Please build language is a full programming language. There are a high level set of build rules that make up a declarative DSL to define build targets, however you can drop into an imperative language that resembles python when necessary:

subinclude("//my_custom_defs:markdown_page")

pages = []
for page in glob(include = ["*.md"]):
    pages += markdown_page(
        name = page.removesuffix(".md"),
        srcs = [page],
        visibility = ["//website/..."],
    )

go_binary (
    name = "webserver",
    srcs = ["main.go"],
    deps = ["//third_party/go:protobuf"],
    data = pages,
    visibility = ["//services/foo/..."],
)

This is distinctively operating at a higher level when compared to make:

protobuf:
    go install google.golang.org/protobuf

webserver: protobuf
    go tool compile --pack foo.go -o foo.a

pages: ???

Additionally, make builds are not hermetic. The above make example installs protobuf into the host machines Go path. Please builds only have access to files and environment variables they have explicitly been given access to. You can play around in the environment targets are built in with plz build //some/target --shell. Additionally, on linux systems, Please can take this a step further with Linux namespaces to improve sandboxing especially of the network. Please also has built in task parallelism so can take full advantage of multi-core machines which were not a consideration 40 years ago when make was designed.

Finally, Please has a robust caching mechanism base on hashing the inputs of each rule. Makes cache invalidation is based on the last modified timestamp which can change unexpectedly forwards and backwards in time. Combine this with hermetic builds, and Please caching is never incorrect.

Why Please, not Bazel, Buck or Pants?

These build systems are all very similar so choosing between them can be hard. Please originally replaced buck implementing the subset of features we used. We found that buck (and the competition) worked great when using the supported languages but fell flat when breaking new ground.

The biggest difference between Please and the competition is that Please is designed from the ground up to be extensible. The built-in languages are all defined in the same build language as you use to define your targets, demonstrating that there's nothing special about them. This puts the build definitions where they should be: in your domain. You have all the same tools Please has to expand your build definitions to satisfy your needs.

Please does all this with a focus on simplicity and transparency. There are a limited amount of concepts that are needed to get started and once they are grocked, the possibilities are endless. Please relies on these concepts rather than requiring lots of magic and incantation. Configuration is simple and largely optional so getting going is easy, and there's no single WORKSPACE file nobody really owns, with lines of configuration that nobody really understands.

The command line interface is designed with similar considerations in mind. Subcommands can be added to Please though aliases and tie into the Please tab-completions. Not only can flags and arguments be completed, but they can also leverage the build graph to complete labels enabling you to truly craft your developer experience the way you want it.

Building Please

If you're looking to get involved, check out the contributor guidance to help you get started. If you're a fan of Please, don't forget to add yourself to the adopters file.

To build Please yourself, run ./bootstrap.sh in the repo root. This will bootstrap a minimal version of Please using Go and then rebuild it using itself.

You'll need to have Go 1.18+ installed to build Please although once built it can target any version from 1.8+ onwards.

Optional dependencies for various tests include Python, Java, clang, gold and docker - none of those are required to build components so their tests will be excluded if they aren't available.

If you'd rather not worry about installing the dependencies, we provide a prebuilt Docker image based on Ubuntu which is capable of building the whole thing for you: docker run -it thoughtmachine/please_ubuntu

You can install a locally built copy of Please using plz install, or if it's the first time, by running ./install.sh after it's built. This will overwrite whatever you currently have in ~/.please with your local version, although you can get back to a released version again by running plz update --force.

To automatically fix linting and code generation issues, run plz autofix.

Documentation

Status

Please is released & we consider it stable; we follow semver for releases, so major versions indicate potentially breaking changes to the BUILD language, command line or other behaviour. We try to minimise this where possible.

We're very happy to accept pull requests, feature requests, and bugs if it's not working for you. We don't always have time for everything but Please is under active development.

bit-shifter/please