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 system user and define the main OMERO.web configuration options as environment variables.

The following steps are run as root.

If required, first create a local system user omero and create the homedir too /home/omero:

useradd -m omero

chmod a+X /home/omero

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

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 https://github.com/ome/zeroc-ice-py-centos7/releases/download/0.2.1/zeroc_ice-3.6.5-cp36-cp36m-linux_x86_64.whl

Install OMERO.web:

/opt/omero/web/venv3/bin/pip install "omero-web>=5.6.dev5"

Installing OMERO.web apps

The following steps are run as root.

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 configure as the omero system user, at any time.

Configuring OMERO.web

The following steps are run as the omero 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:

# If you are installing OMERO.web and OMERO.server on the same machine.
# Point OMERODIR to the OMERO.server
# export OMERODIR=/path_to_omero_server/OMERO.server
export OMERODIR=/home/omero/omero
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
# The command below is not necessary if OMERODIR points to where the OMERO.server is installed
# i.e. OMERO.server and OMERO.web are installed on the same machine.
mkdir -p $OMERODIR/etc/grid


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

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

Configuring Gunicorn

The following steps are run as the omero system user.

Additional settings can be configured by changing the following properties:

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
fi
cp /home/omero/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'

The following steps are run as the omero system user.

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:

[Unit]
Description=OMERO.web
# Not mandatory, NGINX may be running on a different server
Requires=nginx.service
After=network.service

[Service]
User=omero
Type=forking
PIDFile=/home/omero/omero/var/django.pid
Restart=no
RestartSec=10
Environment="OMERODIR=/home/omero/omero"
ExecStart=/opt/omero/web/venv3/bin/omero web start
ExecStop=/opt/omero/web/venv3/bin/omero web stop

[Install]
WantedBy=multi-user.target

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

Maintenance

The following steps are run as the omero system user.

Please read OMERO.web maintenance.

SELinux

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

fi