leeway

README

Leeway is a heavily caching build system for Go, Yarn and Docker projects. Its features are:

• source dependent versions: leeway computes the version of a package based on the sources, dependencies and configuration that make up this package. There's no need (or means) to manually version packages.
• two-level package cache: leeway caches its build results locally and remotely. The remote cache (a Google Cloud Storage bucket) means builds can share their results and thus become drastically faster.
• parallel builds: because leeway understands the dependencies of your packages it can build them as parallel as possible.
• built-in support for Yarn and Go: leeway knows how to link, build and test Yarn and Go packages and applications. This makes building software written in those languages straight forward.
• build arguments: leeway supports build arguments which can parametrize packages at build time. We support version dependent arguments (where the version depends on the argument value), component-wide constants and workspace-level defaults.
• rich CLI: leeways CLI supports deep inspection of the workspace and its structure. Its output is easy to understand and looks good.

Leeway structures a repository in three levels:

• The workspace is the root of all operations. All component names are relative to this path. No relevant file must be placed outside the workspace. The workspace root is marked with a WORKSPACE.yaml file.
• A components is single piece of standalone software. Every folder in the workspace which contains a BUILD.yaml file is a component. Components are identifed by their path relative to the workspace root.
• Packages are the buildable unit in leeway. Every component can define multiple packages in its build file. Packages are identified by their name prefixed with the component name, e.g. some-component:pkg.

Installation

Leeway assumes its running on Linux or macOS. It is very very unlikely that this runs on Windows out-of-the-box. To install, just download and unpack a release.

Build setup

Workspace

Place a file named WORKSPACE.yaml in the root of your workspace. For convenience sake you should set the LEEWAY_WORKSPACE_ROOT env var to the path of that workspace. For example:

touch WORKSPACE.yaml
export LEEWAY_WORKSPACE_ROOT=$PWD

The WORKSPACE.yaml may contain some default settings for the workspace:

# defaultTarget is package we build when just running `leeway build`
defaultTarget: some/package:name
#defaultArgs are key=value pairs setting default values for build arguments
defaultArgs:
  key: value

Component

Place a BUILD.yaml in a folder somewhere in the workspace to make that folder a component. A BUILD.yaml primarily contains the packages of that components, but can also contain constant values (think of them as metadata). For example:

# const defines component-wide constants which can be used much like build arguments. Only string keys and values are supported.
const:
  internalName: example
  someRandomProperty: value
packages:
- ...
scripts:
- ...

Package

A package is an entry in a BUILD.yaml in the packages section. All packages share the following fields:

# name is the component-wide unique name of this package
name: must-not-contain-spaces
# Package type must be one of: go, yarn, docker, generic
type: generic
# Sources list all sources of this package. Entries can be double-star globs and are relative to the component root.
# Avoid listing sources outside the component folder.
srcs:
- "**/*.yaml"
- "glob/**/path"
# Deps list dependencies to other packages which must be built prior to building this package. How these dependencies are made
# available during build depends on the package type.
deps:
- some/other:package
# Argdeps makes build arguments version relevant. I.e. if the value of a build arg listed here changes, so does the package version.
argdeps:
- someBuildArg
# Env is a list of key=value pair environment variables available during package build
env:
- CGO_ENABLED=0
# Config configures the package build depending on the package type. See below for details
config:
  ...

Script

Scripts are a great way to automate tasks during development time (think yarn scripts). Unlike packages they do not run in isolation by default, but have access to the original workspace. What makes scripts special is that they can dependent on packages which become available to a script in the PATH and as environment variables.

Under the scripts key in the component's BUILD.yaml add:

# name is the component-wide unique name of script. Packages and scripts do NOT share a namespace.
# You can have a package called foo and a script called foo within the same component.
name: some-script-name
# description provides a short synopsis of the script. Shown when running `leeway collect scripts`.
description: A sentence describing what the script is good for.
# Deps list dependencies to packages (NOT scripts) which must be built prior to running this script.
# All built dependencies get added to the PATH environment variable. This is handy if your workspace
# contains tools you want to use in a script.
deps:
- some/other:package
# Env sets environment variables which are present during script execution.
env:
- MESSAGE=hello
# Workdir changes the workdir location/layout of working dir of the script. The following choices are available:
# - origin (default): execute the script in the directory of the containing component in the original workspace.
#                     This is the default mode and handy if one wants to automate tasks in the development workspace.
# - packages:         produces a filesystem layout much like during a generic package build where all deps are
#                     found by their name in a temporary directory. This provides some isolation from the original
#                     workspace, while giving full access to the built dependencies.
workdir: origin
# The actual script. For now, only bash scripts are supported. The shebang is added automatically.
scrip: |
  echo $MESSAGE, this is where the script goes
  if [ "A$(ps -o comm= -p $$)" = "Abash" ]; then
    echo "it's the bash alright"
  fi
  echo "build args work to: ${myBuildArg}"

Build arguments

In a package definition one can use build arguments. Build args have the form of ${argumentName} and are string-replaced when the package is loaded. It's advisable to use build args only within the config section of packages. Constants and built-in build args do not even work outside of the config section.

Leeway supports built-in build arguments:

• __pkg_version resolves to the leeway version hash of a component.

Go packages

config:
  # Packaging method. See https://godoc.org/github.com/gitpod/leeway/pkg/leeway#GoPackaging for details. Defaults to library.
  packaging: library
  # If true leeway runs `go generate -v ./...` prior to testing/building. Defaults to false.
  generate: false
  # If true disables `go test -v ./...`
  dontTest: false
  # If true disables the enforcement of `go fmt`. By default, if the code is not gofmt'ed the build fails.
  dontCheckGoFmt: false
  # If true disables the linting stage.
  dontLint: false
  # Overrides the `go build .` command. Supersedes buildFlags.
  buildCommand: []
  # [DEPRECATED: use buildCommand instead] A list of flags passed to `go build`. Useful for passing `ldflags`.
  buildFlags: []
  # Command that's executed to lint the code
  lintCommand: ["golangci-lint", "run"]

Yarn packages

config:
  # yarnlock is the path to the yarn.lock used to build this package. Defaults to `yarn.lock`. Useful when building packages in a Yarn workspace setup.
  # Automatically added to the package sources.
  yarnlock: "yarn.lock"
  # tsconfig is the path to the tsconfig.json used to build this package. Detauls to `tsconfig.json`
  # Automatically added to the package sources.
  tsconfig: "tsconfig.json"
  # packaging method. See https://godoc.org/github.com/gitpod/leeway/pkg/leeway#YarnPackaging for details.
  # Defaults to library
  packaging: library
  # If true disables `yarn test`
  dontTest: false
  # commands overrides the default commands executed during build
  commands:
    install: ["yarn", "install"]
    build: ["yarn", "build"]
    test: ["yarn", "test"]

Docker packages

Docker packages have a default "retagging" behaviour: even when a Docker package is built already, i.e. it's leeway version didn't change, leeway will ensure that an image exists with the names specified in the package config. For example, if a Docker package has leeway/some-package:${version} specified, and ${version} changes, but otherwise the package has been built before, leeway will "re-tag" the previously built image to be available under leeway/some-package:${version}. This behaviour can be disabled using --dont-retag.

config:
  # Dockerfile is the name of the Dockerfile to build. Automatically added to the package sources.
  dockerfile: "Dockerfile"
  # Metadata produces a metadata.yaml file in the resulting package tarball.
  metadata:
    foo: bar
  # build args are Docker build arguments. Often we just pass leeway build arguments along here.
  buildArgs:
  - arg=value
  - other=${someBuildArg}
  # image lists the Docker tags leeway will use and push to
  image:
  - gitpod/leeway:latest
  - gitpod/leeway:${__pkg_version}

Generic packages

config:
  # A list of commands to execute. Beware that the commands are not executed in a shell. If you need shell features (e.g. wildcards or pipes),
  # wrap your command in `sh -c`. Generic packages without commands result in an empty tar file.
  commands:
  - ["echo", "hello world"]
  - ["sh", "-c", "ls *"]

Package Variants

Leeway supports build-time variance through "package variants". Those variants are defined on the workspace level and can modify the list of sources, environment variables and config of packages. For example consider a WORKSPACE.YAML with this variants section:

variants:
- name: nogo
  srcs:
    exclude:
    - "**/*.go"
  config:
    go:
      buildFlags:
        - tags: foo

This workspace has a (nonsensical) nogo variant that, when enabled, excludes all go source files from all packages. It also changes the config of all Go packages to include the -tags foo flag. You can explore the effects of a variant using collect and describe, e.g. leeway --variant nogo collect files vs leeway collect files. You can list all variants in a workspace using leeway collect variants.

Environment Manifest

Leeway does not control the environment in which it builds the packages, but assumes that all required tools are available already (e.g. go or yarn). This however can lead to subtle failure modes where a package built in one enviroment ends up being used in another, because no matter of the environment they were built in, they get the same version.

To prevent such issues, leeway computes an environment manifest which contains the versions of the tools used, as well as some platform information. The entries in that manifest depend on the package types used by that workspace, e.g. if only Go packages exist in the workspace, only go version, GOOS and GOARCH will be part of the manifest. You can inspect a workspace's environment manifest using leeway describe environment-manifest.

You can add your own entries to a workspace's environment manifest in the WORKSPACE.yaml like so:

environmentManifest:
  - name: gcc
    command: ["gcc", "--version"]

Using this mechanism you can also overwrite the default manifest entries, e.g. "go" or "yarn".

Nested Workspaces

Leeway has some experimental support for nested workspaces, e.g. a structure like this one:

/workspace
/workspace/WORKSPACE.yaml
/workspace/comp1/BUILD.yaml
/workspace/otherWorkspace/WORKSPACE.yaml
/workspace/otherWorkspace/comp2/BUILD.yaml

By default leeway would just ignore the nested otherWorkspace/ folder and everything below, because of otherWorkspace/WORKSPACE.yaml. When nested workspace support is enabled though, the otherWorkspace/ would be loaded as if it stood alone and merged into /workspace. For example:

$ export LEEWAY_NESTED_WORKSPACE=true
$ leeway collect
comp1:app
otherWorkspace/comp2:app
otherWorkspace/comp2:lib

• inner workspaces are loaded as if they stood alone: when leeway loads any nested workspace it does so as if that workspace stood for itself, i.e. were not nested. This means that all components are relative to that workspace root. In particular, dependencies remain stable no matter if a workspace is nested or not. E.g. comp2:app depending on comp2:lib works irregardless of workspace nesting.
• nested dependencies: dependencies from an oter workspace into a nested one are possible and behave as if all packages were in the same workspace, e.g. comp1:app could depend on otherWorkspace/comp2:app. Dependencies out of a nested workspace are not allowed, e.g. otherWorkspace/comp2:app cannot depend on comp1:app.
• default arguments: there is one exception to the "standalone", that is defaultArgs. The defaultArgs of the root workspace override the defaults of the nested workspaces. This is demonstrated by leeways test fixtures, where the message changes depending on the workspace that's loaded:

  $ export LEEWAY_NESTED_WORKSPACE=true
  $ leeway run fixtures/nested-ws/wsa/pkg1:echo
  hello world
  
  $ leeway run -w fixtures/nested-ws wsa/pkg1:echo
  hello root
  

• variants: only the root workspace's variants matter. Even if the nested workspace defined any, they'd simply be ignored.

Configuration

Leeway is configured exclusively through the WORKSPACE.yaml/BUILD.yaml files and environment variables. The following environment variables have an effect on leeway:

• LEEWAY_WORKSPACE_ROOT: Contains the path where to look for a WORKSPACE file. Can also be set using --workspace.
• LEEWAY_REMOTE_CACHE_BUCKET: Enables remote caching using GCP buckets. Set this variable to the bucket name used for caching. When this variable is set, leeway expects "gsutil" in the path configured and authenticated so that it can work with the bucket.
• LEEWAY_CACHE_DIR: Location of the local build cache. The directory does not have to exist yet.
• LEEWAY_BUILD_DIR: Working location of leeway (i.e. where the actual builds happen). This location will see heavy I/O which makes it advisable to place this on a fast SSD or in RAM.
• LEEWAY_YARN_MUTEX: Configures the mutex flag leeway will pass to yarn. Defaults to "network". See https://yarnpkg.com/lang/en/docs/cli/#toc-concurrency-and-mutex for possible values.
• LEEWAY_EXPERIMENTAL: Enables exprimental features
• LEEWAY_NESTED_WORKSPACE: Enables nested workspaces. By default leeway ignores everything below another WORKSPACE.yaml, but if this env var is set leeway will try and link packages from the other workspace as if they were part of the parent one. This does not work for scripts yet.

Debugging

When a build fails, or to get an idea of how leeway assembles dependencies, run your build with leeway build -c local (local cache only) and inspect your $LEEWAY_BUILD_DIR.

CLI tips

How can I build a package in the current component/folder?

leeway build .:package-name

Is there bash autocompletion?

Yes, run . <(leeway bash-completion) to enable it. If you place this line in .bashrc you'll have autocompletion every time.

How can I find all packages in a workspace?

# list all packages in the workspace
leeway collect
# list all package names using Go templates
leeway collect -t '{{ range $n := . }}{{ $n.Metadata.FullName }}{{"\n"}}{{end}}'
# list all package names using jq
leeway collect -o json | jq -r '.[].metadata.name'

How can I find out more about a package?

# print package description on the console
leeway describe some/components:package
# dump package description as json
leeway describe some/components:package -o json

How can I inspect a packages depdencies?

# print the dependency tree on the console
leeway describe dependencies some/components:package
# print the denendency graph as Graphviz dot
leeway describe dependencies --dot some/components:package
# serve an interactive version of the dependency graph
leeway describe dependencies --serve=:8080 some/components:package

How can I print a component constant?

# print all constants of the component in the current working directory
leeway describe const .
# print all constants of a component
leeway describe const some/component/name
# print the value of the `someName` constant of `some/component/name`
leeway describe const some/component/name -o json | jq -r '.[] | select(.name=="foo").value'

How can I find all components with a particular constant?

leeway collect components -l someConstant

How can I export only a workspace the way leeway sees it, i.e. based on the packages?

LEEWAY_EXPERIMENTAL=true leeway export --strict /some/destination