OMERO.web installation on CentOS 7 and IcePy 3.6

Please first read OMERO.server installation on CentOS 7.

This is an example walkthrough for installing OMERO.web in a virtual environment using a dedicated system user. Installing OMERO.web in a virtual environment is the preferred way. For convenience in this walkthrough, we will use the omero-web system user and define the main OMERO.web configuration options as environment variables. Since 5.6, a new OMERODIR variable is used, you should first unset OMERO_HOME (if set) before beginning the installation process.

The following steps are run as root.

If required, first create a local system user omero-web and create directory:

useradd -m omero-web

mkdir -p /opt/omero/web/omero-web/etc/grid
chown -R omero-web /opt/omero/web/omero-web

Installing prerequisites

The following steps are run as root.

Install dependencies:

yum -y install epel-release

yum -y install unzip

yum -y install python3

yum -y install nginx

Optional: if you wish to use the Redis cache, install Redis:

yum -y install redis python-redis

systemctl enable redis.service

systemctl start redis.service

Creating a virtual environment

The following steps are run as root.

Create the virtual environment. This is the recommended way to install OMERO.web:

python3 -mvenv /opt/omero/web/venv3

Install ZeroC IcePy 3.6:

/opt/omero/web/venv3/bin/pip install --upgrade

Install OMERO.web:

/opt/omero/web/venv3/bin/pip install "omero-web>=5.6.3"

Installing OMERO.web apps

A number of apps are available to add functionality to OMERO.web, such as OMERO.figure and OMERO.iviewer. See the main website for a list of released apps. These apps are optional and can be installed, as the root user, via pip to your OMERO.web virtual environment and configured as the omero-web system user, at any time.

Configuring OMERO.web

The following steps are run as the omero-web system user.

For convenience the main OMERO.web configuration options have been defined as environment variables. You can either use your own values, or alternatively use the following ones:

export WEBSESSION=True
export OMERODIR=/opt/omero/web/omero-web
export WEBPORT=80
export WEBSERVER_NAME=localhost

Configure OMERO.web and create the NGINX OMERO configuration file:

export PATH=/opt/omero/web/venv3/bin:$PATH

omero config set omero.web.application_server wsgi-tcp
omero web config nginx --http "${WEBPORT}" --servername "${WEBSERVER_NAME}" > /opt/omero/web/omero-web/nginx.conf.tmp

For more customization, please read Customizing your OMERO.web installation.

Configuring Gunicorn

The following steps are run as the omero-web system user.

Additional settings can be configured by changing the properties below. Before changing the properties, run export PATH=/opt/omero/web/venv3/bin:$PATH:

Configuring NGINX

The following steps are run as root.

Copy the generated configuration file into the NGINX configuration directory, disable the default configuration and start NGINX:

sed -i.bak -re 's/( default_server.*)/; #\1/' /etc/nginx/nginx.conf
if [ -f /etc/nginx/conf.d/default.conf ]; then
    mv /etc/nginx/conf.d/default.conf /etc/nginx/conf.d/default.disabled
cp /opt/omero/web/omero-web/nginx.conf.tmp /etc/nginx/conf.d/omeroweb.conf

systemctl enable nginx

systemctl start nginx

Running OMERO.web

The following steps are run as root.

Install WhiteNoise:

/opt/omero/web/venv3/bin/pip install --upgrade 'whitenoise<4'

Optional: Install Django Redis:

/opt/omero/web/venv3/bin/pip install 'django-redis<4.9'

The following steps are run as the omero-web system user.

Optional: Configure the cache:

omero config set omero.web.caches '{"default": {"BACKEND": "django_redis.cache.RedisCache","LOCATION": "redis://"}}'
omero config set omero.web.session_engine 'django.contrib.sessions.backends.cache'

Configure WhiteNoise and start OMERO.web manually to test the installation:

omero config append -- omero.web.middleware '{"index": 0, "class": "whitenoise.middleware.WhiteNoiseMiddleware"}'

omero web start

# Test installation e.g. curl -sL localhost:4080

omero web stop

Automatically running OMERO.web

The following steps are run as root.

Should you wish to run OMERO.web automatically, a systemd.service file could be created. See below an example file omero-web-systemd.service:

# Not mandatory, NGINX may be running on a different server

ExecStart=/opt/omero/web/venv3/bin/omero web start
ExecStop=/opt/omero/web/venv3/bin/omero web stop


Copy the systemd.service file, then enable and start the service:

cp omero-web-systemd.service /etc/systemd/system/omero-web.service

systemctl daemon-reload

systemctl enable omero-web.service

systemctl stop omero-web.service

systemctl start omero-web.service


The following steps are run as the omero-web system user.

Please read OMERO.web maintenance.


The following steps are run as root.

If you are running a system with SELinux enabled and are unable to access OMERO.web you may need to adjust the security policy:

if [ $(getenforce) != Disabled ]; then

    yum -y install policycoreutils-python
    setsebool -P httpd_read_user_content 1
    setsebool -P httpd_enable_homedirs 1
    semanage port -a -t http_port_t -p tcp 4080