JS-Tech/resj

# Deployment guide

This guide contains instruction to deploy the web application on a Jelastic
Cloud.

## Application

The application is run in a docker container built using `.deploy/Dockerfile`.

The container is based on the customizable Phusion Passenger image. The image
let us install a specific Ruby version, NodeJS and Yarn. It also uses Nginx as a
reverse proxy. The image pulls the application code, bundles and resolves the
Javascript dependencies (node, yarn and packages). Finally, one startup script
runs the database migrations. Jelastic Cloud already provides services when
running the image (`cron`, `sshd`, etc.) via `systemd`. Therefore, the cron
service is disabled in the Passenger's image.

Build the container with: 

```sh
docker build --secret id=master_key,env=RAILS_MASTER_KEY . -t resj
```

The environment variable `RAILS_MASTER_KEY` must be set with corresponding
value.

To run the container:

```sh
docker run -d -e RAILS_MASTER_KEY=secret resj 
```

On the Jelastic dashboard, simply load the custom image and set the following
environment variables:

- RAILS_MASTER_KEY
- POSTGRES_HOST
- POSTGRES_PORT
- POSTGRES_USER
- POSTGRES_PASSWORD

## Database

TODO

## Load balancer

HAProxy is used as the single entrypoint to the services. The config file `haproxy.cfg` must contain the following blocks (replace `%IPADDRESS` with the IP address of the service):

```
# Define hosts
acl host_ghost hdr(host) -i ghost.reseaujeunesse.ch
acl host_blog hdr(host) -i blog.reseaujeunesse.ch
acl host_resj hdr(host) -i reseaujeunesse.ch

# Decide which host to use
use_backend ghost_cluster if host_ghost
use_backend ghost_cluster if host_blog
default_backend resj_cluster

backend default
mode http
errorfile 503 /etc/haproxy/welcome.http
 
backend ghost_cluster
server webserver1 %IPADDRESS:${BACKEND_PORT} check cookie S1
mode http
cookie SRVNAME insert
balance roundrobin

backend resj_cluster
server webserver1 %IPADDRESS:${BACKEND_PORT} check cookie S1
mode http
cookie SRVNAME insert
balance roundrobin
```

Finally, to display a custom error when a service is unavailable (e.g an app is deploying), put the error page in `var/lib/haproxy/errors/503.http`. Add the following line in `defaults` block:

```
errorfile 503 /var/lib/haproxy/errors/503.http
```

## Backup

TODO

# Deploy a new version

Deploy the latest version from master by creating a new release. An action will
automatically create and publish a new docker image and trigger a redeploy on
Jelastic. Note that during the redeploy the website will suffer a downtime of
~1m30. This could be fixed by using horizontal scaling, which is not worth the
extra cost.