# agl-docker-worker

## Purpose

This repository contains some scripts to generate a Docker image suitable for AGL workers. 

The AGL worker image is a Docker image based on Debian 8 and contains the necessary tools
either to build platform images based on Yocto, or run the AGL SDK to build AGL Applications
outside of Yocto process.

## Requirements

Have a recent docker daemon (>=1.10) installed. All the setup is done inside the image so no other tool is required on the host.

## Usage

To get some help, simply run:
```
make help
```

Typically, the sequence to build an image is:

```
# make build
...
# make export
...
# make clean
```

## How it works

The Dockerfile is generic: it simply inherits from a Debian image.
When running a 'docker build':

* Docker instantiates a new container based on the latest Debian image
* Docker copies the current directory inside the container in /root/INSTALL
* then it runs the setup script /root/INSTALL/docker/setup_image.sh

In turn, this setup script will:

* source the configuration file /root/INSTALL/docker/image.conf
* execute all scripts contained in /root/INSTALL/setup.d

When the setup script finishes, Docker commits the temporary container in a new image.

This image can then be exported to a tarball and/or pushed to a Docker registry.

## Using the generated image

### Grab the image

To publish the image, there are 2 ways: using a docker registry OR exporting to a tarball.

In the first case, using the image is very easy as it can be pulled directly from the registry host using a 'docker pull' command. The main issue with this method is the efficiency: images are not compressed and it takes ages to transfer overlays to the client host.

In the second case, the efficiency is better but requires to transfer the image archive manually. On the client host, loading the image is as simple as:

```
# wget -O - <archive_url> | docker load
```

### Instantiate a container

The following command can be used as an example to instantiate a container:


```
# ./create_container 0
```

To instantiate more containers on the same host, the instance ID passed as argument must be different from the previous ones.