# Docker for Building/Running crosvm

This module contains various pieces of Docker infrastructure for supporting crosvm outside of Chrome
OS environments. This includes the kokoro build environment.

[TOC]

## Introduction

Ordinarily, crosvm is built using the standard `cargo build` command inside of a Chrome OS chroot.
The chroot requirement is there because of various path dependencies in the crosvm `Cargo.toml` are
targeted to paths outside of the crosvm repo itself. If one were to checkout crosvm in isolation,
`cargo build` would be inadequate, failing with an error related to these missing paths.
Additionally, crosvm depends on native packages that are not ordinarily available from an OS package
manager (e.g. minijail) or have been forked in the Chrome OS project in an incompatible fashion
(libusb).

## `crosvm-base` Docker Image

To support building crosvm outside of a Chrome OS chroot, this modules contains a `Dockerfile` that
is used to build the `crosvm-base` docker image. Part of that image build process is downloading
various repos, checking out pinned commits (specified in `checkout_commits.env`), and installing
them. For the path dependencies in the `Cargo.toml`, the `Dockerfile` downloads and places the
source code in the correct spot relative to the crosvm source repository. The `crosvm-base` build
step stops short of actually building crosvm. It doesn't even have the source code for crosvm. The
intent here is to use `crosvm-base` for building and running any version of crosvm.

To build the `crosvm-base` image, run `build_crosvm_base.sh`. The script will automatically use the
checkouts from `checkout_commits.env` which can be reconfigured to point to any commit desired. To
upgrade `checkout_commits.sh` to the HEAD of each remote master branch, run the
`upgrade_checkout_commits.sh` script.

## `crosvm` Docker Image

After generating a `crosvm-base`, the system is ready to build crosvm into its own `crosvm` docker
image. The resulting docker image will be capable of running VMs without fear of missing native
dependencies. Run the `build_crosvm.sh` script to build crosvm into a docker image. Once that
completes, use the `crosvm_wrapper.sh` script to run crosvm within the docker image. That script
will pass the arguments given to it verbatim to crosvm. In addition, the current working directory
is bind mounted into the container so that file paths passed to `crosvm_wrapper.sh` should work as
long as they are relative paths to files contained in the working directory.

## `smoke_test`

There is a convenience wrapper for `smoke_test` that uses the `crosvm` docker image to execute
all the tests. Run `wrapped_smoke_test.sh` after building `crosvm-base` docker image to run the
`smoke_test` within docker.