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ALLGO containers
================


Overview
--------

A minimal deployment of allgo consists of 4 docker images:

- **allgo/rails**: the rails application server 
- **allgo/mysql**: the mysql database server
- **allgo/docker**: the manager for user docker containers
- **allgo/ssh**: the ssh frontend (giving access to the sandboxes)

These images may be deployed multiple times to implement multiple independent
environments (eg: production, qualification, ...).

Additionally there are two images that are meant to be deployed only once (they
may serve multiple environments)

- **allgo/registry**: the docker registry
- **allgo/nginx**: the frontal http server

There is an extra image used only in development:

- **allgo/smtpsink**: a SMTP server that catches and stores all incoming messages into a single mailbox

Each environment has its own docker network. The nginx container is connected
to all these networks to that it can connect to the rails servers.


Conventions
-----------

All docker images use the following conventions.

### External volumes

They data is stored in:

  - `/vol/rw` for persistent data
  - `/vol/ro` for persistent data in read-only access
  - `/vol/cache` for cache data (persistent data that may be destroyed at any time without any consequence)
  - `/vol/log` for the logs

These paths are expected to be mounted as external volumes, either separately (typical for a production deployment) or with a single mount at `/vol` (typical for a development environment). The owner of external volumes must be the same as the uid used for the app inside the container.

### Admin scripts

Each container may contain a set of scripts for admin purpose (especially for managing the content of external volumes)

  - `/dk/container_init` initialise the content of the external volumes (eg: create and seed a database, write a default config, ...)
  - `/dk/image_upgrade` apply security upgrades to the image. This command is expected to exit with 0 if successful and to output something on stdout/stderr when something was upgraded an nothing if nothing was upgraded (thus if the output is empty, it is not necessary to commit a new image). 



Development environment
-----------------------

The development environment is managed with docker-compose. There are 3 important files:

 - `docker-compose.yml` the docker-compose configuration
 - `prepare.sh` a shell script which is meant to be sourced in the shell before
   working with the environment
 - `bootstrap` the bootstrap script

It provides 7 containers:

 - `dev-docker`
 - `dev-mysql`
 - `dev-nginx`
 - `dev-rails`
 - `dev-registry`
 - `dev-smtpsink`
 - `dev-ssh`

All external volumes are stored in `/data/dev/` (the path is absolute because
it is tricky to use a relative path with the allgo/docker image).

For convenience, all containers not running as root (rails, mysql, registry)
have their user overridden to the UID:GID of the developer running
docker-compose. This is managed with the `DOCKER_USER` environment variable set
by `prepare.sh`.

For convenience (again), there is an extra external volumes for `dev-rails`,
`dev-docker` and `dev-ssh` so that the source directory of the app is mounted
inside `/opt/` (in fact it overrides the actual application files provided by
the docker image). The purpose is to avoid rebuilding a new docker image for
each development iteration. 


### Getting started

The sources are located in two repositories:

 - *rails-allgo*: the rails application repository
 - *allgo*: the deployment repository

To set up the development environment, run: 

 1. get the sources
 	<pre>
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	git clone git@gitlab.irisa.fr:charly.maupetit/rails-allgo.git -b docker
	git clone git@gitlab.irisa.fr:sebastien.campion/allgo.git -b docker
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	cd allgo
	</pre>
	**Note:** the *allgo* repository has a symbolic link to the
	*rails-allgo* repository. They should be cloned at the same place (or
	the link will be broken).

 2. *(as root)* create `/data/dev` and make it owned by the developer
	<pre>
	sudo mkdir -p    /data/dev
	sudo chown USER: /data/dev
	</pre>

 3. source the `prepare.sh` script (to be run every time before you start working)
 	<pre>
	. prepare.sh
	</pre>

 4. bootstrap the environment
 	<pre>
	./bootstrap
	</pre>
	This command will run the `/dk/init_container` in every container that
	needs it, then start the container.

	The first run takes a very long time because all images are built from
	scratch (especially the rails image which builds ruby source).
	You have enough time for a coffee break.

	**Note** by default `bootstrap` works on all containers. It is possible
	to give an explicit list of containers instead. Example:
	<pre>
		./bootstrap dev-mysql dev-rails
	</pre>

 5. for convenience, you may want to alias `docker-compose` as `fig` (because
     `fig` is much faster to type than `docker-compose` and you will have to
     type it a lot). Somewhere in your `.bashrc` you should add:
	<pre>
	alias fig=docker-compose
	</pre>


### Common commands

The official doc for docker-compose is available at: [https://docs.docker.com/compose/
https://docs.docker.com/compose/]()

 - start all containers (in the background)
	<pre>
	fig up -d
	</pre>

 - start all containers (in the foreground, i.e interactively, when you hit Ctrl-C all containers are stop)
	<pre>
	fig up -d
	</pre>

 - soft cleanup (stop and remove all containers)
	<pre>
	fig down
	</pre>

 - hard cleanup (remove images too)
 	<pre>
	fig down --rmi local
	</pre>

 - restart a container
	<pre>
	fig restart dev-rails
	</pre>

 - restart a container using a new docker image (if the image has been rebuilt since the last start)
 	<pre>
	fig up dev-rails
	</pre>

 - rebuild an image
 	<pre>
	fig build dev-railf
	</pre> 

 - **Note:** most commands work on every container by default (eg: up down
   start stop restart ...) they can be use on an individual container too:
   	<pre>
	fig restart dev-docker dev-rails
	</pre>

 - run a container with an arbitrary command (eg: to have access to the rails console)
 	<pre>
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	fig run --rm dev-rails bash
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	</pre>

	**Note:** containers created by `fig run` have the same parameters as
	the referenced containers but their name is different (eg:
	*allgo_dev-ssh_run_1*), which means that this container is not
	reachable by the others (this may be an issue for example if you want
	to run the mysqld server manually: `fig run dev-mysql mysqld` -> this
	container won't be reachable by the ssh and rails containers)

 - follow the output of all containers:
 	<pre>
	fig logs --tail=1 --follow
	</pre>

Production environment
----------------------

- TODO unicorn/nginx integration
- TODO use capistrano too ?


Images design
-------------


## registry

Hosts docker registry with a nginx configured as a reverse proxy. It listens to 4 ports:

 - :8000 (*production*) access limited to `/v2/allgo/prod/`
 - :8001 (*qualification*) access limited to `/v2/allgo/qualif/`
 - :8002 (*development*)  access limited to `/v2/allgo/dev`
 - :5000 (*legacy production*) access limited to `/v2/allgo`(which is mapped to `/v2/allgo/prod/`)

## mysql

Hosts a mysql server listening on port 3306 with two databases: `allgo` and
`allgo_test` and two users: `allgo` and `ssh`.

 - `allgo` has read/write access to both databases
 - `ssh` has read only access to `allgo`


## rails

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Hosts four daemons for running allgo:
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 - the unicorn server (runnning the rails application)
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 - the sidekiq queue manager
 - the redis db server
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 - a nginx frontend for buffering the HTTP requests/responses

This container is managed with supervisor, the `supervisorctl` command allows
starting/stopping the daemons individually.

### Running the rails server manually


 - run the `dev-rails` container and open a shell:
	<pre>
	fig up -d
	docker exec -t -i  dev-rails bash
	</pre>

 - then, inside the container, run:
	<pre>
	supervisorctl stop rails
	rails server
	</pre>
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## ssh

Hosts the ssh front server for accessing the sandboxes (`ssh
WEBAPP@sid.allgo.irisa.fr`). Each allgo webapp is mapped to a system user
(using Glibc NSS) starting at uid 2000.

- `/etc/passwd` and `/etc/group` are overriden so as to contain only the two users (*root* and *sshd*) and one group (*nogroup*) required to run the ssh server
- Extra users are obtained from the mysql database (using libnss-mysql-bg) and mapped as follows:
	<pre>
	name  = webapps.docker_name
	uid   = webapps.id
	gid   = 65534 (nogroup)
	gecos = webapps.name
	shell = /bin/allgo-shell
  	</pre>
- The ssh server is configured to accept key-based authentication only. The
  list of public keys is obtained from the (using an AuthorizedKeysCommand).

- The forced shell (`allgo-shell`) connects to the webapp sandbox (if running).

- The connection to the sandbox is made though a unix socket and a set of pipes
  in the filesystem.

## docker

Hosts the *docker-allgo-proxy* which manages all docker operations (run, stop,
rm, commit, pull, push, ...) on behalf of the rails container.

Technically speaking this container had root privileges since it has access to
the docker socket.

The proxy script enforces restrictions (according to the current environment: eg prod/qualif/dev) on:

 - the registry (for pulling/pushing)
 - the paths of external volumes 
 - the container names (*ENV*-user-*XXXX*)

## nginx

Hosts the frontal nginx server, its purpose is to:
- give access to one or more allgo instances
- manage TLS encryption

## smtpsink

Hosts a SMTP server (port 25) and an IMAP server (port 143) for
development/qualification

Its purpose is to channel all outgoing mail (received on port 25) into a single
mailbox.

The mailbox is accessible with IMAP as user *sink* (password *sink*).