# CCE Search Frontend System Information and Provisioning Guide

Instance ID: i-0fb314b098444b089 

Availability Zone: us-east-2b

Public DNS: ec2-3-16-54-35.us-east-2.compute.amazonaws.com

Elastic IP: 3.15.80.81

URL: [cce.ebookfoundation.org](cce.ebookfoundation.org)

OS: Ubuntu 18.04


### UFW:
- Disallowed incoming by default
- Allowed outgoing by default
- Allowed SSH, HTTP, HTTPS, NginxHTTP, OpenSSH
- Enabled UFW after setting up rules
- Info [here](https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-18-04)


### Added apt repositories:
- universe (may be enabled by default)
- ppa:certbot/certbot
- ppa:deadsnakes/ppa

*Note: remember to run sudo apt update after adding repositories*


### Installing Python 3.7 and Pip3:
While Ubuntu 18.04 comes with Python 3.6, adding the [deadsnakes PPA](https://linuxize.com/post/how-to-install-python-3-7-on-ubuntu-18-04/) allows for the installation of Python 3.7. However, linking the python3 command to Python 3.7 may cause issues with applications that use `#!/usr/bin/python3`. See the errors section of this document for information about fixing these issues. To counteract this, use the python3.7 command instead, and perform pip installs with `python3.7 -m pip install x`, rather than `pip3 install x`.


### Installed apt packages:
- git (may be installed by default)
- nginx
- software-properties-common (may be installed by default, prerequisite for installing python3.7)
- python3.7
- python3-pip
- certbot
- python-certbot-nginx


### Installed Pip3 packages:
- pipenv (`python3.7 -m pip install pipenv`)


### Nginx:
- Set up as reverse proxy for app, running on port 80
- [Use NGINX as a Reverse Proxy](https://www.linode.com/docs/web-servers/nginx/use-nginx-reverse-proxy/)
- https://gunicorn.org/#deployment (we don’t use gunicorn but this is the basis of the configuration)
- The following config file should be saved as /etc/nginx/conf.d/cce-search.conf:
```
server {
  listen 80;
  server_name cce.ebookfoundation.org;
  access_log /var/log/nginx/cce-search.log;

  location / {
    proxy_pass http://127.0.0.1:5000;
  }
}
```
- Nginx is automatically configured to run on server reboot
- See [here](https://www.digitalocean.com/community/tutorials/how-to-install-nginx-on-ubuntu-18-04)


### Certbot (Let’s Encrypt/SSL tool):
- See [here](https://certbot.eff.org/lets-encrypt/ubuntubionic-nginx)
- Get cert and configure Nginx for HTTPS with `sudo certbot --nginx`
- Email is support@ebookfoundation.org
- Choose to redirect HTTP traffic to HTTPS
- Certificate and chain saved at: `/etc/letsencrypt/live/cce.ebookfoundation.org/fullchain.pem`
- Key file saved at: `/etc/letsencrypt/live/cce.ebookfoundation.org/privkey.pem`
- Cert should automatically renew


### Setting up the application to run as a service:
- Save the following ([source](https://blog.miguelgrinberg.com/post/running-a-flask-application-as-a-service-with-systemd)) in `/etc/systemd/system/cce-search-frontend.service`:
```
[Unit]
Description=The CCE Search Flask application (cce.ebookfoundation.org)
After=network.target

[Service]
User=ubuntu
WorkingDirectory=/home/ubuntu/cce-search-frontend
ExecStart=/home/ubuntu/.local/bin/pipenv run flask run
Restart=always

[Install]
WantedBy=multi-user.target
```
- Run `sudo systemctl daemon-reload` to load the service


### Deploy the latest source code with Ansible:
- Install Ansible on your machine, then use the update-frontend-prod playbook [here](https://github.com/EbookFoundation/cce-search-ansible) to deploy the application once the server is provisioned 


## Errors and how to fix them


### Running add-apt-repository returns `ImportError: cannot import name '_gi' from 'gi' (/usr/lib/python3/dist-packages/gi/__init__.py)`(or something similar):
- This is caused because the python3 command runs a different version (3.7) than the default system version
- To fix, edit the first line of /usr/bin/add-apt-repository to say `#!/usr/bin/python3.6`
- See here: [Changed Python version, "apt-add-repository" not working ERROR](https://askubuntu.com/questions/717866/changed-python-version-apt-add-repository-not-working-error)


### Running `sudo certbot --nginx` returns `ModuleNotFoundError: No module named '_cffi_backend'`:
- Need to install cffi: `sudo python3 -m pip install cffi`
- See: [No module named _cffi_backend](https://stackoverflow.com/questions/34370962/no-module-named-cffi-backend)


### Going to the IP Address in your browser shows the app, but going to the Public DNS shows the default Nginx page:
- Edit the server_name in `/etc/nginx/conf.d/cce-search.conf` (remember to sudo)
- Test modifications with `sudo nginx -t`
- If accepted, `sudo systemctl restart nginx`
- See [Using Amazon EC2: IP address working fine, but public DNS not](https://stackoverflow.com/questions/34300216/using-amazon-ec2-ip-address-working-fine-but-public-dns-not)


### Locked yourself out of the server because you disallowed ssh connections in UFW and then logged off
- Hahaha
- See: [Locked myself out of SSH with UFW in EC2 AWS](https://stackoverflow.com/questions/41929267/locked-myself-out-of-ssh-with-ufw-in-ec2-aws)