# OMERO.web installation for developers

## Getting set up

You will need to have an OMERO server running that you can connect to. This could be on your own machine `localhost` or you can connect to a remote OMERO server.

The preferred option for developing OMERO.web apps is to install `omero-web` on your machine as described below.

However, it is also possible to use omero-web-docker to run OMERO.web in a Docker container. If you are using this option, you can go directly to the Creating an app page which describes this process.

## Installing OMERO.web

From OMERO 5.6.0 release, the `omero-web` library supports Python 3 and can be installed via pip. We need to specify an `OMERODIR` location where omero-web will create log files and a `config.xml` file. This can be any existing directory.

We recommend you use a virtual environment and start by installing `omero-py` as described at omero-py.

    # Somewhere to create config and log files
    $ export OMERODIR=$(pwd)

    $ pip install 'omero-web>=5.31.0'

## Using the lightweight development server

All that is required to use the Django lightweight development server is to set the `omero.web.application_server` configuration option, and turn `omero.web.debug` on. If you want to connect to a remote OMERO server, add that as shown. Then start up the development server to run in the foreground:

    $ omero config set omero.web.application_server development
    $ omero config set omero.web.debug True
    $ omero config append omero.web.server_list '["server.address", 4064, "name"]'
    $ omero web start
    INFO:__main__:Application Starting...
    INFO:root:Processing custom settings for module omeroweb.settings
    ...
    Validating models...

    0 errors found
    Django version 3.2, using settings 'omeroweb.settings'
    Starting development server at http://127.0.0.1:4080/
    Quit the server with CONTROL-C.

You should now be able to open http://localhost:4080 in your browser, choose the OMERO server and login.

## Using WSGI

For convenience you may wish to run a web server under your local user account instead of using a system server for testing. Install NGINX and Gunicorn (See OMERO.web installation and maintenance) but generate a configuration file using the following commands:

    $ omero config set omero.web.application_server 'wsgi-tcp'
    $ omero web config nginx-development > nginx-development.conf

Start NGINX and the Gunicorn worker processes running one thread listening on 127.0.0.1:4080 that will autoreload on source change:

    $ nginx -c $PWD/nginx-development.conf
    $ omero config set omero.web.application_server.max_requests 1
    $ omero config set omero.web.wsgi_args -- "--reload"
    $ omero web start

Next: Get started by Creating an app….