Visu-back

---

Visu-back is the backend of the visu project. Visu is a geospatial data analyse tool.

📝 Table of Contents

• About
• Getting Started
• Deployment
• Usage
• Built Using
• TODO
• Contributing
• Authors
• Acknowledgments

🧐 About

Visu-back is the backend part of the TerraVisu application.

🏁 Getting Started

This section take you by the hand through a series of steps to install a working version of the backend part of the visu application. Start here if you want a working version of the platform.

There is two parts for the application, the backend and the frontend. Each part has his own instructions. To see the frontend part go to the frontend repository

Prerequisites

In order to install the backend server application, you need to fulfil the following requirements:

• A linux server with a recent kernel
• docker >= 18.6 installed
• docker-compose >= 1.23.0 installed
• Any load balancer (HaProxy, Traefik, ...) to redirect queries to backend (and frontend)
• A hostname pointing to the backend server
• Optional (recommended): a set of extra subdomains also pointing to the backend server to serve tiles from the same server but bypass the browser limit. Drastically improve performances
• Optional: you can use an instance of sentry to track server errors

Installation

These instructions will guide you to install the application on a development server. For production purpose, you should understand what you are doing, and use docker-compose-prod.yml file.

Visu-back offers an API that is consumed by the frontend.

To install it we need to achieve the following steps:

• Get the latest version
• Configure the application
• Bootstrap the instance
• Populate initial database

Get the latest version

You can clone the source code by executing:

git clone https://github.com/terralego/visu-back.git

/!\ The following commands must be executed in the root directory of the backend application.

Configure

To configure the application before the first startup, you need to adapt two files to your needs.

First the docker.env file:

$ cp docker.env.dist docker.env

Use your preferred editor to edit the created file and modify the values. Read the comments in the file to get hints on the purpose of each variable.

You can now copy the settings file:

$ cp src/project/settings/local.py.dist src/project/settings/local.py

Also edit this file to make the values meet your needs. Again, comments can help you to find the appropriate values.

Hint: You may have to add 0.0.0.0 to ALLOWED_HOSTS in local.py. Also, you need to set TERRA_TILES_HOSTNAMES setting to API url. In development environment it should be set to http://localhost:8000 if you expose gunicorn ports, or http://localhost/ if you expose API through nginx. Setting your mapbox token and background style is also recommended.

Finally, copy .env.dist file to .env. The file is used when deploying a production environment to set the django built image's name and tag:

$ cp .env.dist .env

Bootstrap the instance

After a last verification of the files, to run with docker, just type:

For development purpose

# First time you download the app, or sometime to refresh the image
docker-compose -f docker-compose.yml -f docker-compose-dev.yml pull # Call the docker compose pull command
docker-compose -f docker-compose.yml -f docker-compose-dev.yml build # Should be launched once each time you want to start the stack
docker-compose -f docker-compose.yml -f docker-compose-dev.yml up django # Should be launched once each time you want to start the stack
# Take care that no migrations are run, so you can't launch celery/celerybeat container until migration are applied.
docker-compose -f docker-compose.yml -f docker-compose-dev.yml up # For normal start when migration are applied

For production purpose

# First time you download the app, or sometime to refresh the image
docker-compose -f docker-compose.yml -f docker-compose-prod.yml pull # Call the docker compose pull command
docker-compose -f docker-compose.yml -f docker-compose-prod.yml build # Should be launched once each time you want to start the stack
docker-compose -f docker-compose.yml -f docker-compose-prod.yml up django # Should be launched once each time you want to start the stack
# Migrations will automatically be run with production settings. Once the initial migrations are done, you can launch all containers
docker-compose -f docker-compose.yml -f docker-compose-prod.yml up # Should be launched once each time you want to start the stack

notes: The first startup can be long (5 ~ 10 minutes) as all docker images will be downloaded and/or built.

Populate the database

Wait for the startup to finish, then, while keeping it running, go in an other shell and populate the database with the following commands:

$ docker-compose exec django /code/venv/bin/python /code/src/manage.py migrate # to migrate the database if needed
$ docker-compose exec django /code/venv/bin/python /code/src/manage.py populatedata # Launch a shell inside django container

If you want some demo data, you can also execute:

$ docker-compose exec django /code/venv/bin/python /code/src/manage.py populatedata -t # Test data

To be able to connect you need to create a super user. Execute:

```sh
$ docker-compose exec django /code/venv/bin/python3 /code/src/manage.py createsuperuser

Your instance is now up and running.

To test it you can execute:

curl http://localhost:<port>/api/settings/

You should get a json in response.

After that you can stop the server by doing a Ctrl-c inside the first shell.

You should now configure your load balancer to serve requests to the backend and proceed to the frontend installation.

Notes:: if you want to serve backend and frontend from the same domain, you must serve backend from the following prefixes: api/, admin/, cms/, media/, static_dj/, 502.html, mailcatcher/ and the frontend for everything else.

Troubleshooting

In general

If you get troubles with the nginx docker env restarting all the time, try recreating it:

docker-compose -f docker-compose.yml -f docker-compose-dev.yml up -d --no-deps --force-recreate nginx backup

If you get the same problem with the django docker env:

docker-compose -f docker-compose.yml -f docker-compose-dev.yml stop django db
docker volume rm visu-postgresql # check with docker volume ls
docker-compose -f docker-compose.yml -f docker-compose-dev.yml up -d db
# wait fot postgis to be installed
docker-compose -f docker-compose.yml -f docker-compose-dev.yml up django

Virtual memory areas error

elasticsearch_1   | [1]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
  sudo sysctl -w vm.max_map_count=262144

sysctl -w vm.max_map_count=262144 # To make it effective immediatly sudo vim /etc/sysctl.conf -> vm.max_map_count=262144 # To keep it on next startup

🎈 Usage

Start a shell inside the django container

• for user shell

docker-compose exec django bash

Calling Django manage commands

docker-compose  exec django /code/venv/bin/python3 /code/src/manage.py shell [options]
# For instance:
# docker-compose exec django /code/venv/bin/python3 /code/src/manage.py migrate
# docker-compose exec django /code/venv/bin/python3 /code/src/manage.py shell
# docker-compose exec django /code/venv/bin/python3 /code/src/manage.py createsuperuser
# ...

Docker volumes

Your application extensively uses docker volumes. From times to times you may need to erase them (eg: burn the db to start from scratch)

docker volume ls  # hint: |grep \$app
docker volume rm $id

⛏️ Built Using

• ElasticSearch - Database
• Django - Python Framework
• DjangoRestFramework - Rest Framework
• Redis - Broker

✍️ Authors

• @terralego - Idea & Initial work