ci/README.md

# Containerized build & test utilities

This folder contains scripts and dockerfiles used to build and test MXNet using
Docker containers

You need docker and nvidia docker if you have a GPU.

If you are in ubuntu an easy way to install Docker CE is executing the
following script:


```
#!/bin/bash
set -e
set -x
export DEBIAN_FRONTEND=noninteractive
apt-get -y install curl
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
      $(lsb_release -cs) \
         stable"
apt-get update
apt-get -y install docker-ce
service docker restart
usermod -a -G docker $SUDO_USER
```

For detailed instructions go to the [docker installation instructions](https://docs.docker.com/engine/installation/linux/ubuntu/#install-using-the-repository).


## build.py

The main utility to build is build.py which will run docker and mount the mxnet
folder as a volume to do in-place builds.

The build.py script does two functions, build the docker image, and it can be
also used to run commands inside this image with the propper mounts and
paraphernalia required to build mxnet inside docker from the sources on the
parent folder.

A set of helper shell functions are in `docker/runtime_functions.sh`.
`build.py` without arguments or `build.py --help` will display usage
information about the tool.

To build for armv7 for example:

```
./build.py -p armv7
```


To work inside a container with a shell you can do:

```
./build.py -p ubuntu_cpu -i
```

When building, the artifacts are located in the build/ directory in the project root. In case
`build.py -a` is invoked, the artifacts are located in build.<platform>/

## Add a platform

To add a platform, you should add the appropriate dockerfile in
docker/Dockerfile.build.<platform> and add a shell function named
build_<platform> to the file docker/runtime_functions.sh with build
instructions for that platform.

## Warning
Due to current limitations of the CMake build system creating artifacts in the
source 3rdparty folder of the parent mxnet sources concurrent builds of
different platforms is NOT SUPPORTED.

## ccache
For all builds a directory from the host system is mapped where ccache will store cached 
compiled object files (defaults to /tmp/ci_ccache). This will speed up rebuilds 
significantly. You can set this directory explicitly by setting CCACHE_DIR environment 
variable. All ccache instances are currently set to be 10 Gigabytes max in size.