Install on Ubuntu

This section describes how to install Docker Engine on Ubuntu, also known as Docker CE. Docker Engine is also available in numerous Linux platforms you can find here: Install Docker Engine. Docker Engine is also available for Windows, macOS, and Linux, through Docker Desktop. For instructions on how to install Docker Desktop, see: Overview of Docker Desktop.

Install eMedia on Ubuntu and Docker

curl -o entermedia-docker.sh -jL get-em11.entermediadb.org && sudo bash ./entermedia-docker.sh xyzcorp 100

Once complete you should then be able to connect locally from the host machine: curl http://172.18.0.100:8080

eMedia will be stored in your host computer by default at: /media/emsites/xyzcorp

 

Continue with eMedia installation and configuration here.

 

Advanced Setup

Firewall

Disable the CSF Firewall that is not compatible with Docker. Edit and use our simple customization IPTables firewall script. You only have to edit LOCAL_NETWORK=192.168.100.0 to match your custom Network. Follow this instructions to make Iptables firewall rules persistent on reboot. To setup a cluster of Docker instances

  • The firewall script allows certain IP addresses to have access to port 9200 and 9300 that ElasticSearch uses for clustering. It also allows the NFS ports to be open so that the site can be shared among the nodes.
  • There are several options for clustering:
    • Share the /media/emsites/xyzcorp drive among all the nodes as a network drive
    • Run all the nodes on one machine with a shared volume
    • Experimental: Use a bi-directional sync tool such as https://getsync.com/ to keep /media/emsites/xyzcorp in sync
  • Always use a unique port number for each Docker instance even if they are other servers. This allows unique node id's to be defined.

 

DNS

By default, if Docker can’t find a DNS server locally defined in your /etc/resolv.conf file, containers will default to using Google’s public DNS server, 8.8.8.8, to resolve DNS.

In some office networks, the administrators intentionally block the use of public DNS servers to encourage people to use the network’s own DNS server.

You can get your internal DNS server IP running the following command:

 nmcli dev show | grep 'IP4.DNS'

Or by checking the /etc/resolv.conf file on your host machine.

Then update the Docker daemon by editing the following file:

vi /etc/docker/daemon.json { "dns": ["INTERNAL_DNS_IP", "8.8.8.8"] } 
sudo service docker restart

 

Starting on Bootup

 sudo sysctl docker on *** deprecated sudo systemctl enable docker

Setup Docker service to start after the Firewall service and any NFS mount required by eMEdia. Modify Docker service config file at:

 sudo vi /usr/lib/systemd/system/docker.service

to looks something like:

 [Unit] 
 Description=Docker Application Container Engine 
 Documentation=https://docs.docker.com 
 After=network-online.target firewalld.service "opt-entermedia-webapp-WEB\x2dINF-data.mount" 
 Wants=network-online.target 
 ConditionPathExists=/opt/entermedia/webapp/WEB-INF/data/media

Now restart systemctl daemon:

 sudo systemctl daemon-reload

 

Cluster of Dockers

Across machines: Each node needs to have the host computers IP addresses set. See: /media/emsites/xyzcorp/100/tomcat/conf/node.xml  

 <property id="discovery.zen.ping.unicast.hosts">172.101.0.100:9300,172.101.0.101:9300</property> 
 <property id="network.bind_host">0.0.0.0</property> 
 <property id="network.publish_host">172.101.0.100</property>

Note that the publish host has to match the external IP address of the host machine. Also check that the firewall script allows local network traffic to ElasticSearch ports as configured in entermedia-docker.sh i.e. 9100

 

Troubleshooting

If you receive a networking error stating conflicts or issues with the entermedia network then edit the entermedia-docker.sh script and look for the line with:

 docker network create --subnet 172.18.0.0/16 entermedia

Change this to different subnet IP address range and run the script again.

Note that if you have trouble creating multiple instances it might be because the unique identifier in entermedia is not the IP address but the name of the instance.

Instance xyzcorp at 172.18.0.100:8080 will be the same entermedia database as xyzcorp at 172.18.0.200:8080

The following instances created through our script must have different names, xyzcorpB, xyzcorpC, etc.

 

ubuntu|linux|docker