Cool Solution - Guacamole

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Note: Cool Solutions are articles documenting additional functionality based on Univention products. Not all of the shown steps in the article are covered by Univention Support. For questions about your support coverage contact your contact person at Univention before you want to implement one of the shown steps.

Also regard the legal notes at Terms of Service.


Guacamole is a clientless remote desktop gateway. It supports standard protocols like VNC and RDP.

The version of Guacamole used in this article is Guacamole 0.9.8.

Installation

To successfully deploy and start Guacamole, three images must be downloaded via Docker:

  • guacd
  • guacamole
  • mysql

At the moment, Docker images of Guacamole can only be started when a database is provided.

Hint: Instead of MySQL, PostgreSQL can be used as well. In this case the image postgres must be downloaded. Refer to the Docker documentation and Guacamole manual for downloading and configuring PostgreSQL. This article will use the MySQL connection.

Configuration

Automatically start Docker container

If the container should start automatically, eg. after a server reboot, add the following line to the docker run command:

--restart=always

MySQL

Download and deploy the MySQL image:

docker run --name mysql -e MYSQL_ROOT_PASSWORD=<MYSQL_PASSWORD> -d mysql:5.7.7

Hint: Change <MYSQL_PASSWORD> to an actual password of your choice.

This will download and deploy the MySQL image and provide an instance as "mysql". After the command is finished, a 65 character long ID is printed out. Save this ID for the next step.

guacd

Download and deploy the guacd image:

docker run --name guacd -d glyptodon/guacd

This will provide the guacd daemon that handles all Guacamole connections. Nothing more must be done with this container.

Creating the Guacamole database

First, run the following command to create the tables for the database:

docker run --rm glyptodon/guacamole /opt/guacamole/bin/initdb.sh --mysql > initdb.sql

Hint: This command will also download the Guacamole image, but does not start Guacamole for using. This is a one-time command and should not contain a --restart parameter.

Next, copy the local file initdb.sql to the MySQL Docker container:

cp initdb.sql /var/lib/docker/overlay/<MySQL ID>/merged/root/

Replace <MySQL ID> with the ID you saved in the step above.

Next, connect to the MySQL container to create the Guacamole databse, user and tables:

docker exec -it mysql bash

This will provide a bash inside the MySQL container.

Next, connect to MySQL to create the database and user for Guacamole:

mysql -uroot -p<MYSQL_PASSWORD>
CREATE DATABASE guacamole_db;
CREATE USER 'guacamole_user'@'%' IDENTIFIED BY '<GUACAMOLE_PASSWORD>';
GRANT SELECT,INSERT,UPDATE,DELETE ON guacamole_db.* TO 'guacamole_user'@'%';
FLUSH PRIVILEGES;
quit

Hint: Change <GUACAMOLE_PASSWORD> to the actual password used for the Guacamole database user.

Next, create the database structure needed by Guacamole:

cat /root/initdb.sql | mysql -uroot -p<MYSQL_PASSWORD> guacamole_db

Leave the container with:

exit

guacamole

Since the Guacamole image is already downloaded, just deploy Guacamole itself. Guacamole comes with a Apache Tomcat8 server:

docker run --name guacamole --link guacd:guacd --link mysql:mysql \
-e MYSQL_DATABASE=guacamole_db \
-e MYSQL_USER=guacamole_user \
-e MYSQL_PASSWORD=<GUACAMOLE_PASSWORD> \
-d -p 8181:8080 glyptodon/guacamole

With the parameter -p 8181:8080, the Tomcat port 8080 from inside the container is routed to the local port 8181. This is done to prevent other software, like Zarafa (which also uses port 8080) to malfunction.

Apache

To provide Guacamole via Apache, add the following site as a new file guacamole to your Apache installation in /etc/apache2/sites-available:

<Location /guacamole>
	Order allow,deny
	Allow from all
	ProxyPass http://localhost:8181/guacamole max=20 flushpackets=on
	ProxyPassReverse http://localhost:8181/guacamole
</Location>

Next you must make the new site available and reload the Apache webserver:

a2ensite guacamole
invoke-rc.d apache2 reload

It is possible to get access to Guacamole via Tomcat. For this, please refer to the Tomcat manual for accessing applications.

UCS overview

To configure the UCS startsite to provide a link to Guacamole as a webservice, the UCR variables ucs/web/overview/entries/service must be set:

ucr set \
ucs/web/overview/entries/service/guacamole/description/de="Guacamole für Remote-Zugriff per RDP oder VNC." \
ucs/web/overview/entries/service/guacamole/description="Guacamole for accessing remote systems via RDP or VNC." \
ucs/web/overview/entries/service/guacamole/icon="/guacamole/images/logo-64.png" \
ucs/web/overview/entries/service/guacamole/label/de="Guacamole" \
ucs/web/overview/entries/service/guacamole/label="Guacamole" \
ucs/web/overview/entries/service/guacamole/link="/guacamole"

The above configuration assumes that your Guacamole installation is configured via Apache. The UCR variable ucs/web/overview/entries/service/guacamole/link must be changed accordingly.

After that, you can access you Guacamole installation via http://FQDN-of-your-UCS/guacamole or via the overview site http://FQDN-of-your-UCS/ucs-overview.

Note: The default administration user is guacadmin, the password is guacadmin. It is advised to change the password after the first login! To do this, open the top-right drop down menu and go to Settings → Preferences.

Authentication

Guacamole can be configured to use several backends for authentication:

Hint: Please take note, that only one authentication module can be active at time! The default for this Docker image is the MySQL authentication. Users can be configured via the settings menu from the administrator account.

Accessing the container

The conainter can either be accessed by starting a shell inside the container:

docker exec -it guacamole bash

or by changing into the started Docker container's filesystem directory in the local server's filesystem:

DOCKER_ID=$(docker ps --no-trunc | awk '/glyptodon\/guacamole:latest/ {print $1}')
cd /var/lib/docker/overlay/"${DOCKER_ID}"/merged

Installing auth plugins

To install other authentication methods than the MySQL authentication, download the according plugin from here (section Compatible extensions in the top right corner). To install another auth plugin, download the desired plugin and place it inside the mysql or postgres folder in /opt/guacamole in the Guacamole container, and remove any other auth plugin available in that folder. For accessing the container, look at Accessing the container.

Hint: Depending on how you initally configured the Guacamole container, choose either mysql or postgres.

Next, add a line near the end to the /opt/guacamole/bin/start.sh script to enable your plugin. In case of the noauth plugin:

Before:

[...]
#
# Finally start Guacamole (under Tomcat)
#

start_guacamole

After:

[...]
#
# Finally start Guacamole (under Tomcat)
#

echo "noauth-config: /opt/guacamole/noauth.xml" >> $GUACAMOLE_HOME/guacamole.properties
start_guacamole

Save the file and restart the docker container:

docker restart guacamole

It can take up to five minutes until Tomcat is started and Guacamole deployed.

Example configuration

An example for the noauth-plugin against a UCC terminal server using RDP:

<configs>
	<config name="UCC session" protocol="rdp">
		<param name="hostname" value="ucc-ts" />
		<param name="port" value="3389" />
	</config>
</configs>

The configuration must be saved in the file /opt/guacamole/noauth.xml inside the Guacamole container.

Further information

More information about configuration can be obtained from the Guacamole manual.

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