capsul-flask/docs/deployment.md

# Deploying Capsul on a server

Capsul has a ["hub and spoke" architecture](./architecture.md). The "Hub" runs the web application and talks to the Postgres database, while the "Spoke"s are responsible for creating/managing virtual machines. One instance of the capsul-flask application can run in both hub mode and spoke mode at the same time, however there must only be one instance of the app running in "Hub" mode at any given time.

## <a name="spoke_mode_prerequisites"></a>Installing prerequisites for Spoke Mode

On your spoke (see [Architecture](./architecture.md) You'll need `libvirtd`, `dnsmasq`, and `qemu-kvm`, plus a `/tank` diectory with some operating system images in it:

```
sudo apt install libvirt-daemon-system virtinst git dnsmasq qemu qemu-kvm
sudo mkdir -p /var/www /tank/{vm,img,config}
sudo mkdir -p /tank/img/debian/10
cd !$
sudo wget https://cloud.debian.org/images/cloud/buster/20201023-432/debian-10-genericcloud-amd64-20201023-432.qcow2 -O root.img.qcow2
```

TODO: network set-up


## cyberia-cloudinit.yml

The create vm shell script depends on this file. I think right now its file path is hard-coded to `/tank/config/cyberia-cloudinit.yml`

```
#cloud-config
preserve_hostname: true
users:
  - name: cyberian
    groups: wheel
    lock_passwd: true
    shell: /bin/bash
    sudo: ['ALL=(ALL) NOPASSWD:ALL']
    ssh-authorized_keys:
```

### Metrics

Capsul integrates with Prometheus to grab the data for the capsul metric graphs. 

The code that generates those metrics is here: https://github.com/kumina/libvirt_exporter

### autonomic / servers.coop version for ipv6 support 

```
#cloud-config
package_upgrade: true
packages:
  - curl
  - wget
  - git
  - vim
bootcmd:
  - echo 'iface ens3 inet6 dhcp' >> /etc/network/interfaces.d/50-cloud-init
  - ifdown ens3; ifup ens3
final_message: "The system is finally up, after $UPTIME seconds"
users:
  - name: user
    groups: sudo
    sudo: ['ALL=(ALL) NOPASSWD:ALL']
    ssh-authorized-keys:
```


## Deploying capsul-flask

### <a name="deploy_manually"></a>Manually

Follow the [local set-up instructions](./local-set-up.md) on your server. 

Make sure to set `BASE_URL` correctly, generate your own secret tokens, and
configure your own daemon management for the capsul-flask server (e.g. writing
init scripts, or SystemD unit files).

Use the suggested `gunicorn` command (with appropriately-set address and port),
instead of `flask run`, to launch the server.

For example, here is the SystemD service unit file we use in production for `capsul.org`:

```
[Unit]
Description=capsul-flask virtual machines as a service
After=network.target

[Service]
ExecStart=/usr/local/bin/pipenv run gunicorn --bind 127.0.0.1:5000 -k gevent --worker-connections 1000 app:app
Restart=on-failure
WorkingDirectory=/opt/capsul-flask

[Install]
WantedBy=multi-user.target

```

TODO: cron runner is required to run maintenance tasks for now, but in the future we want to build this into the python based task scheduler. 

### <a name="coop_cloud_docker"></a> Using Co-op Cloud's vanilla Docker Swarm configuration

Download the Co-op Cloud swarm `compose.yml`:

```sh
wget https://git.autonomic.zone/coop-cloud/capsul/src/branch/main/compose.yml
```

Optionally, download add-on compose files for Stripe, BTCPay, and Spoke Mode:

```sh
wget https://git.autonomic.zone/coop-cloud/capsul/src/branch/main/compose.{stripe,btcpay,spoke}.yml
```

Then, create a `.env` file and configure appropriately -- you probably want to
define most settings in [the Co-op Cloud `.envrc.sample`
file](https://git.autonomic.zone/coop-cloud/capsul/src/branch/main/.envrc.sample).

Load the environment variables (using Python `direnv`, or a manual `set -a && source .env && set +a`), insert any necessary secrets, then run the deployment:

```sh
docker stack deploy -c compose.yml -c compose.stripe.yml your_capsul
```

(where you'd add an extra `-c compose.btcpay.yml` for each optional compose file
you want, and set `your_capsul` to the "stack name" you want).

TODO: cron runner

### <a name="coop_cloud_abra"></a> Using Co-op Cloud's `abra` deployment tool

Follow [the guide in the README for the Co-op Cloud capsul package](https://git.autonomic.zone/coop-cloud/capsul/).

### Using docker-compose

TODO