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Notice: the master branch is for development work on the upcoming 2.0 release, which is still unstable. Any changes to a previous version of core should be developed against master and then cherry-picked onto the 1.x branch.

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Driver Core Library for Scala Services

Multi-cloud utilities and application initialization framework.

This library offers many common utilities for building applications that run in multiple environments, including Google Cloud, Ali Cloud, and of course on development machines.

Highlights

• Cloud agnostic.

• Sensible defaults. Applications that use the initialization framework can run out-of-the box on cloud or locally, with minimal config required.

• Distributed tracing built into all major utilities. Significant actions are logged and reported automatically to an OpenTrace aggregator.

• Extensible. Utilities are built to be used standalone. A trait-based initialization framework provides utility instances for common use-cases.

Overview

Components

This project is split into multiple submodules, each providing specific functionality.

Project	Description
core	(deprecated) Previous application initialization framework.
core‑database	Utilities for working with databases, slick in particular.
core‑init	Mini-framework that offers default instances of many utilities, configured for the current platform.
core‑messaging	Library for abstracting over message buses such as Google PubSub.
core‑reporting	Combined tracing and logging library.
core‑rest	Abstractions to represent RESTful services, discovery and client implementations.
core‑storage	Object storage utilities.
core‑testkit	Mixins for scalatest.
core‑types	Type definitions that are commonly used by applications.
core‑util	Other utilities that do not belong anywhere else. Note that this is a staging place for code that does not have its own submodule yet. Do not depend on it externally!

These components and their internal dependencies can be represented with the following graph.

Dependency

All components are published together under the same version (latest version).

libraryDependencies += "xyz.driver" %% "core-<component>" % "<version>"

External dependencies

This project has quite a few external dependencies. See build.sbt for a list of them. Some notable Scala libraries used are:

• akka-http
• akka-stream
• enumeratum
• scala-async
• slick
• spray-json
• sttp

Example Usage

The following implements a simple key-value store that uses object storage ("buckets") when running in the cloud and a local filesystem when running on a development machine.

import xyz.driver.core.init

object Main extends init.SimpleHttpApp {

  lazy val fs = storage("data")

  override def applicationRoute = path("data" / Segment) { key =>
    post {
      entity(as[Array[Byte]]) { value =>
        complete(fs.uploadContent(key, value))
      }
    } ~ get {
      rejectEmptyResponse{
        complete(fs.content(key))
      }
    }
  }

}

See this example project for a more details.

Building

This project uses sbt as build tool. It has grown organically over time, but all new code should follow the best practices outlined here.

It is set up to automatically build, test, and publish a release when a Git tag is pushed that matches the regular expression v[0-9].*. Hence, to publish a new version "1.2.3", simply create a tag "v1.2.3" and git push --tags to origin.

Copying

Copyright 2016-2018 Driver Inc. Released under the Apache License, Version 2.0.