Installation

The app depends on PyWPS and several other libraries that are listed in requirements.txt. It is advisable to run it using a python virtualenv to prevent package instalation problems:

$ virtualenv -p python3 pywps_flask_env
$ cd pywps_flask_dir
$ . bin/activate
$ git clone https://github.com/geopython/pywps-flask
$ cd pywps-flask
$ pip3 install -r requirements.txt

If python virtualenv is not an option:

$ git clone https://github.com/geopython/pywps-flask
$ cd pywps-flask
$ pip3 install -r requirements.txt

For Debian based systems you will need to install GDAL with:

$ sudo apt-get install python3-gdal

When using only using requirement.txt, the pywps-flask will run for the directory that was pulled from github, for a system wise installation is it advisable to use setup.py:

$ git clone https://github.com/geopython/pywps-flask
$ cd pywps-flask
$ python3 setup.py install

Running

Simply run the python file:

$ python3 demo.py -a

The flag -a will bind to the ip range 0.0.0.0 and is normally the safest option access to pypwps-flask

The -d option will run pywps-flask as daemon and to stop it is necessary to determine the PID and kill it, one trick is to use fuser to determine PID, and then use it to kill the process:

$ fuser tcp/5000
$ kill -15 <PID RETURNED PREVIOUSLY>

Docker images

The docker folder contains 2 subfolders, each subfolder contains a differente pywps implementation.

Folder flask has the default pywps-flask implementation using only Flask while folder nginx implements pywps using Nginx and Green unicorn as WSGI server. While folder ubuntu has the same images but using phusion image (ubuntu 18.04)

Flask-Alpine (basic)

Basic pywps image is based on Alpine 3.8 and will run the native Flask service, this is not apropriate for production. The docker file can be found in: docker/alpine/flask/Dockerfile

To build the image (inside the folder with the Dockerfile):

$ docker build -t pywps/flask-alpine .

And to run it:

$ docker run -p 5000:5000 pywps/flask-alpine:latest

Pywps will be available in the following URL:

$ http://localhost:5000

Gunicorn-Alpine (production)

This image implements the previous flask-alpine image (you need to build it first, or it will be automatically pulled from dockerhub) but wrapping flask in a WSGI server (gunicorn) where each worker runs a an app. This image allows for the following environment variables:

• GU_WORKERS - Numer or workers. Gunicorn uses a set of workers to run pywps (normally workers = (2 * cpu) + 1). (default: 5)
• GU_PORT - Port running Gunicorn (default:8081)

Gunicorn-Alpine is locate in folder docker/alpine/gunicorn/Dockerfile

This image can already be implemented in production but it is advisable to use Nginx for HTTP load balance and Gunicorn as WSGI server (see below)

To build the image (inside the folder with the Dockerfile):

$ docker build -t pywps/gunicorn-alpine:latest .

And to run it:

$ docker run -p 8081:8081 -it pywps/gunicorn-alpine:latest

or:

$ docker run -e GU_WORKERS=10 -e GU_PORT=8082  -p 8082:8082 -it pywps/gunicorn-alpine:latest

Pywps will be available at the following URL:

$ http://localhost:8082

Nginx-Alpine

This is the complete stack intented for production, to have a stack we require to use docker-compose to build two images: pywps/gunicorn-alpine:latest and pywps/nginx-alpine:latest

Those images will be pulled from dockerhub, but they can compiled locally by building Flask-Alpine, Gunicron-Alpine and Nginx-Alpine, in this case only showing for nginx:

$ cd docker/alpine/nginx/Dockerfile
$ docker build -t pywps/nginx-alpine:latest .

Then the stack can be started using docker compose:

$ docker-compose up

In this case pywps (only the WPS) will be avalable on:

http://localhost

Flask-Ubuntu (basic)

The same as Flask-Ubuntu but using phusion image (ubuntu 18.04):

$ cd docker/ubuntu/flask
$ docker build -t pywps/flask-ubuntu:latest .

And to run it:

$ docker run -p 5000:5000 pywps/flask-ubuntu

Nginx-Ubuntu (production)

This image is based on Flask-Ubuntu and will require it (either build locally or pull from dockerhub). This image has Nginx and Gunicorn totally integrated as services in a docker image:

$ cd docker/ubuntu/nginx
$ docker build -t pywps/nginx-ubuntu .

And to run it:

$ docker run -p 80:80 pywps/nginx-ubuntu

It is possible to set the number of Gunicorn workers:

• GU_WORKERS - Numer or workers. (default: 5)

e.g:

$ docker run -e GU_WORKERS=10 -p 80:80 pywps/nginx-ubuntu

Volumes

Named volumes allow for container content to be available in the host system. The most important folders in pywps containers are:

• /pywps-flask/logs
• /pywps-flask/outputs
• /pywps-flask/processes

And file: * /pywps-flask/pywps.cfg

Named volumes need to be created prior to docker run:

$ docker volume create pywps_logs
$ docker volume create pywps_outputs
$ docker volume create pywps_processes

To check the path on the host to volume and other information:

$ docker volume ls pywps_processes

To run a docker will all the volumes available in the host:

$ docker run -p 5000:5000 -v pywps_logs:/pywps-flask/pywps_logs \
                          -v pywps_outputs:/pywps-flask/pywps_outputs \
                          -v pywps_processes:/pywps-flask/pywps_processes \
                          -v pywps_cfg:/pywps-flask/pywps.cfg  pywps/flask-alpine:latest

THE END