Overview

Buildsonnet is a work-in-progress, general-purpose build tool based on the Jsonnet language with built-in support for building scala code through bloop. Scala project configuration is similar to Sbt but done using jsonnet's object mix-in features rather than a scala DSL. The Jsonnet standard library is extended with functions for running command-line jobs and compiling and running scala code.

Buildsonnet can be compiled with graal native-image for fast startup times. Scala compilations are dispatched to a bloop instance using the build server protocol and the included bloop-launcher.

Jobs are cached using file timestamps with results stored in an sqlite database.

Motivation

Sbt's extensiblity comes from its lazily evaluated settings keys that are defined using a scala DSL. It is also where a lot of my frustrations with sbt come from. The reliance on a scala DSL makes start-up times slow, and project configurations unnecessarily verbose and complex.

Mill relies on scala inheritance for project configuration. While this approach may result in more understandable code, it is also very verbose and requires a scala interpreter.

The Jsonnet language provides a lot of the same functionality of sbt project keys with a more concise syntax. Not having to run a full scala interpreter makes start-up times fast.

Standard Library Extensions

Buildsonnet extends the Jsonnet standard libary with helpers for running scala build commands and running jobs. Note that these are side-effecting functions that may modify the build workspace. This means that Buildsonnet loses the hermeticity of Jsonnet. Currently jobs are run without any sandboxing and are cached using timestamps. A potential future enhancement would be to run jobs using Bazel's sandboxfs and use file hashes instead of timestamps.

std.scala.Dep(org, name, version, crossVersion=null)

Helper for creating a scala dependency object e.g.

{
  org: '',
  name: '',
  version: '',
  crossVersion: 'for3Use2_13'
  type: 'scala'
}

std.scala.Project

An object mix-in that can be used to create a scala project. It provides, bloopConfig, compile, classpath, and run fields.

The parent object is required to define name, scalaVersion, and sources and optionally dependencies and libraries. e.g.

{
  bloopgun: std.scala.Project {
    name: "bloopgun",
    sources: [
      "bloop/bloopgun/src/main/scala",
      std.write("bloop/bloopgun/generated_src/BloopgunInfo.scala", |||
        package bloopgun.internal.build

        /** This object was generated by buildsonnet. */
        case object BloopgunInfo {
          val version: String = "0.1.0-SNAPSHOT"
          override val toString: String = "version: $version"
        }
      |||)
    ],
    scalaVersion: scala213Version,
    libraries: [
      std.scala.Dep("me.vican.jorge", "snailgun-cli", "0.4.0"),
      std.java.Dep("org.zeroturnaround", "zt-exec", "1.11"),
      std.java.Dep("org.slf4j", "slf4j-nop", "1.7.2"),
      std.scala.Dep("io.get-coursier", "coursier", "2.0.16"),
      std.scala.Dep("io.get-coursier", "coursier-cache", "2.0.16"),
      std.scala.Dep("com.github.plokhotnyuk.jsoniter-scala", "jsoniter-scala-core", "2.4.0"),
      std.scala.Dep("com.github.plokhotnyuk.jsoniter-scala", "jsoniter-scala-macros", "2.4.0"),
      std.java.Dep("org.bouncycastle", "bcprov-jdk15on", "1.64"),
      std.java.Dep("org.bouncycastle", "bcpkix-jdk15on", "1.64"),
    ],
  },

  bloopLauncher: std.scala.Project {
    name: "bloop-launcher",
    dependencies: [$.bloopgun],
    sources: ["bloop/launcher/src/main/scala"],
    scalaVersion: scala213Version,
    libraries: [
      std.scala.Dep("io.get-coursier", "coursier", "2.0.16"),
      std.scala.Dep("io.get-coursier", "coursier-cache", "2.0.16"),
      std.java.Dep("org.scala-sbt.ipcsocket", "ipcsocket", "1.4.0",),
    ],
  },

  compileBloopLauncher: $.bloopLauncher.compile // compile using bloop bsp
  runBloopLauncher(args): $.bloopLauncher.run(args) // run using bloop bsp
  runForkBloopLauncher(args): $.bloopLauncher.runFork(args) // run using 'java -cp ...' subprocess
  bloopLauncherClasspath: $.bloopLauncher.classpath // prints the classpath
}

std.scala.cs(deps, withSources=false)

Takes an array of std.scala.Dep objects and fetches their jars using coursier. Returns an array of jar paths in classpath order. Fetches source jars if withSources is set to true.

std.scala.jvm(name, index="https://github.com/coursier/jvm-index/raw/master/index.json")

Fetches a jvm using coursier.

std.scala.compile(project)

Compiles a std.scala.Project object using bloop. Will launch a bloop bsp on port 8212 if one does not already exist.

std.scala.run(project, main, args, jvmOptions, environmentVariables)

Runs a std.scala.Project object using bloop. Will launch a bloop bsp on port 8212 if one does not already exist.

std.runJob(desc)

Takes a job description and runs it, returning a job result object. Jobs are cached based on file timestamps. e.g.

std.runJob({
  cmdline: ['java', '-cp', $.bloopLauncher.classpathString, main, args],
  envVars: {
    HOME: std.getenv("HOME"),
    JAVA_HOME: std.getenv("JVM_HOME"),
  },
  inputFiles: [$.bloopLauncher.classpathPaths],
  outputFiles: ['out/foo', 'out/bar'],
})