Django 3.2 version of ZOSIA registration page.

• Development
  • Full in-docker local development
    • Required software
    • How can I run it?
    • I have run it - what is happening?
  • Troubleshooting
• Hosting

The preferred approach is to use docker for development. And don't worry, we try to keep it as easy as possible. Of course, if you're really not into containerisation, you can try running it without docker, but you may find it harder to debug OS related bugs. Besides, on production site we run this application in docker, so it's better to keep your development process similar to the production one.

To run container for development you need to have Docker (Community Edition) installed, as well as a docker-compose-plugin installed on your system.

For Debian-based systems use APT:

sudo apt install docker-ce docker-ce-cli containerd.io docker-compose-plugin

For RPM-based systems:

sudo yum install docker-ce docker-ce-cli containerd.io docker-compose-plugin

To keep things simple we've written dev.py script inside tools directory. It can run everything for you, simply type python3 dev.py run or ./dev.py run. No root permissions are needed. All commands used with the script are listed under ./dev.py --help and help for command CMD under ./dev.py CMD --help (e.g. ./dev.py run --help).

There are 3 flags that you might want to use with dev.py run:

• --create-admin - create super user / admin account with the password of your choice
• --create-data - generate some semi-random data - the implementation can be found here: src/conferences/management/commands/create_data.py. This command also generates several user accounts zosia[1-5]?@example.com that can be accessed with password: pass.
• --no-cache - build the fresh copy of the container image (ignore docker cache)

First, script needs to build the docker image. This process uses local cache, so it takes time at the first run only, because docker has to pull python image and build every layer. Then two containers have started: zosia_db_1 with Postgres database and zosia_web_1 with our web application.

We mount some local folders so as to let you develop application without rebuilding docker every time:

• ./app/src as /code/src
• ./app/js as /code/js
• ./app/static as /code/static

Thanks to this, all changes you make in the code will be visible immediately inside the container. Remember that this works in both directions! Every change you'll make in the container will affect your local files (from the listed folders), because these are the same files, of course :P

We tried to avoid side effects in our dev.py script, but sometimes it can't be achieved easily. Some commands may create files inside listed folders. This files will be owned by root, because they were created inside docker. You don't have to worry about them, we listed them in .gitignore file, so they should not appear in git status.

Files created in directory /code/static are output from the webpack build system (these are JS and CSS files). They will be created in your local filesystem and fortunately will be ignored by version control. Moreover, NodeJS module required by our application are installed. They will exist inside docker container only, so they won't be copied into your local filesystem. If you'd like your JS file to be rebuilt after editing them, run command ./dev.py javascript watch in new terminal.

Next, we run migrations on database and, finally, start the web server. In terminal you will see output/logs from django (e.g. queries to the database).

You can shut this server down anytime by clicking CTRL+C, but containers will be still alive. If you want to start the web server again, just run ./dev.py server. If you want to shut all containers down, you need to run ./dev.py quit command.

Creating network "zosia_default" with the default driver
ERROR: could not find an available, non-overlapping IPv4 address pool among the defaults to assign to the network

This error can appear during docker compose up command if you have VPN activated on your system. There has been no solution found yet. You have to disconnect from VPN, run docker compose up and when containers are finally up you may enable your VPN again.

Creating network "zosia_default" with the default driver
ERROR: Failed to program FILTER chain: iptables failed: iptables --wait -I FORWARD -o br-123123123123 -j DOCKER: iptables v1.X.Y: Couldn't load target `DOCKER':No such file or directory

In case of that error just restart docker daemon service with this command: systemctl restart docker

In case of any other problems it is recommended to rebuild the container with --no-cache option (i.e. ./dev.py run --no-cache or ./dev.py start --no-cache).

We hosted ZOSIA registration site on AWS. We used an ECS cluster based on EC2 instances to run the containers and ECR as a docker registry. All secrets (like database credentials, different APIs keys, etc) were stored in the Parameter Store and loaded to the environment variables on container startup. Deployments were conducted by CircleCI after every commit to the master branch. All deployment scripts used for that are placed in the .ecs directory.

We hosted the ZOSIA site on GCP App Engine with GCP SQL as Postgres managed database. Deployments were still done using CircleCI pipelines.