the_information_nexus/random/guacamole_docker.md

Installing Guacamole with Docker

Guacamole can be deployed using Docker, removing the need to build guacamole-server from source or configure the web application manually. The Guacamole project provides officially-supported Docker images for both Guacamole and guacd which are kept up-to-date with each release.

A typical Docker deployment of Guacamole will involve three separate containers, linked together at creation time:

guacamole/guacd

Provides the guacd daemon, built from the released guacamole-server source with support for VNC, RDP, SSH, telnet, and Kubernetes.

guacamole/guacamole

Provides the Guacamole web application running within Tomcat 8 with support for WebSocket. The configuration necessary to connect to guacd, MySQL, PostgreSQL, LDAP, etc. will be generated automatically when the image starts based on Docker links or environment variables.

mysql or postgresql

Provides the database that Guacamole will use for authentication and storage of connection configuration data.

This separation is important, as it facilitates upgrades and maintains proper separation of concerns. With the database separate from Guacamole and guacd, those containers can be freely destroyed and recreated at will. The only container which must persist data through upgrades is the database.

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Running the guacd Docker image

The guacd Docker image is built from the released guacamole-server source with support for VNC, RDP, SSH, telnet, and Kubernetes. Common pitfalls like installing the required dependencies, installing fonts for SSH, telnet, or Kubernetes, and ensuring the FreeRDP plugins are installed to the correct location are all taken care of. It will simply just work.

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Running guacd for use by the Guacamole Docker image

When running the guacd image with the intent of linking to a Guacamole container, no ports need be exposed on the network. Access to these ports will be handled automatically by Docker during linking, and the Guacamole image will properly detect and configure the connection to guacd.

$ docker run --name some-guacd -d guacamole/guacd

When run in this manner, guacd will be listening on its default port 4822, but this port will only be available to Docker containers that have been explicitly linked to some-guacd.

The log level of guacd can be controlled with the GUACD_LOG_LEVEL environment variable. The default value is info, and can be set to any of the valid settings for the guacd log flag (-L).

$ docker run -e GUACD_LOG_LEVEL=debug -d guacamole/guacd

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Running guacd for use by services outside Docker

If you are not going to use the Guacamole image, you can still leverage the guacd image for ease of installation and maintenance. By exposing the guacd port, 4822, services external to Docker will be able to access guacd.

:::{important} Take great care when doing this - guacd is a passive proxy and does not perform any kind of authentication.

If you do not properly isolate guacd from untrusted parts of your network, malicious users may be able to use guacd as a jumping point to other systems. :::

$ docker run --name some-guacd -d -p 4822:4822 guacamole/guacd

guacd will now be listening on port 4822, and Docker will expose this port on the same server hosting Docker. Other services, such as an instance of Tomcat running outside of Docker, will be able to connect to guacd directly.

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The Guacamole Docker image

The Guacamole Docker image is built on top of a standard Tomcat 8 image and takes care of all configuration automatically. The configuration information required for guacd and the various authentication mechanisms are specified with environment variables or Docker links given when the container is created.

:::{important} If using PostgreSQL or MySQL for authentication, you will need to initialize the database manually. Guacamole will not automatically create its own tables, but SQL scripts are provided to do this. :::

Once the Guacamole image is running, Guacamole will be accessible at {samp}http://{HOSTNAME}:8080/guacamole/, where HOSTNAME is the hostname or address of the machine hosting Docker.

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Configuring Guacamole when using Docker

When running Guacamole using Docker, the traditional approach to configuring Guacamole by editing guacamole.properties is less convenient. When using Docker, you may wish to make use of the enable-environment-properties configuration property, which allows you to specify values for arbitrary Guacamole configuration properties using environment variables. This is covered in .

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Connecting Guacamole to guacd

The Guacamole Docker image needs to be able to connect to guacd to establish remote desktop connections, just like any other Guacamole deployment. The connection information needed by Guacamole will be provided either via a Docker link or through environment variables.

If you will be using Docker to provide guacd, and you wish to use a Docker link to connect the Guacamole image to guacd, the connection details are implied by the Docker link:

$ docker run --name some-guacamole \
    --link some-guacd:guacd        \
    ...
    -d -p 8080:8080 guacamole/guacamole

If you are not using Docker to provide guacd, you will need to provide the network connection information yourself using additional environment variables:

GUACD_HOSTNAME

The hostname of the guacd instance to use to establish remote desktop connections. This is required if you are not using Docker to provide guacd.

GUACD_PORT

The port that Guacamole should use when connecting to guacd. This environment variable is optional. If not provided, the standard guacd port of 4822 will be used.

The GUACD_HOSTNAME and, if necessary, GUACD_PORT environment variables can thus be used in place of a Docker link if using a Docker link is impossible or undesirable:

$ docker run --name some-guacamole \
    -e GUACD_HOSTNAME=172.17.42.1  \
    -e GUACD_PORT=4822             \
    ...
    -d -p 8080:8080 guacamole/guacamole

A connection to guacd is not the only thing required for Guacamole to work; some authentication mechanism needs to be configured, as well. MySQL, PostgreSQL, and LDAP are supported for this, and are described in more detail in the sections below. If the required configuration options for at least one authentication mechanism are not provided, the Guacamole image will not be able to start up, and you will see an error.

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MySQL authentication

To use Guacamole with the MySQL authentication backend, you will need either a Docker container running the mysql image, or network access to a working installation of MySQL. The connection to MySQL can be specified using either environment variables or a Docker link.

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Initializing the MySQL database

If your database is not already initialized with the Guacamole schema, you will need to do so prior to using Guacamole. A convenience script for generating the necessary SQL to do this is included in the Guacamole image.

To generate a SQL script which can be used to initialize a fresh MySQL database as documented in :

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

Alternatively, you can use the SQL scripts included with the database authentication.

Once this script is generated, you must:

1. Create a database for Guacamole within MySQL, such as guacamole_db.

2. Create a user for Guacamole within MySQL with access to this database, such as guacamole_user.

3. Run the script on the newly-created database.

The process for doing this via the {command}mysql utility included with MySQL is documented .

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Connecting Guacamole to MySQL

If your MySQL database is provided by another Docker container, and you wish to use a Docker link to connect the Guacamole image to your database, the connection details are implied by the Docker link itself:

$ docker run --name some-guacamole \
    --link some-guacd:guacd        \
    --link some-mysql:mysql        \
    ...
    -d -p 8080:8080 guacamole/guacamole

If you are not using Docker to provide your MySQL database, you will need to provide the network connection information yourself using additional environment variables:

MYSQL_HOSTNAME

The hostname of the database to use for Guacamole authentication. This is required if you are not using Docker to provide your MySQL database.

MYSQL_PORT

The port that Guacamole should use when connecting to MySQL. This environment variable is optional. If not provided, the standard MySQL port of 3306 will be used.

The MYSQL_HOSTNAME and, if necessary, MYSQL_PORT environment variables can thus be used in place of a Docker link if using a Docker link is impossible or undesirable:

$ docker run --name some-guacamole \
    --link some-guacd:guacd        \
    -e MYSQL_HOSTNAME=172.17.42.1  \
    ...
    -d -p 8080:8080 guacamole/guacamole

Note that a Docker link to guacd (the --link some-guacd:guacd option above) is not required any more than a Docker link is required for MySQL. The connection information for guacd can be specified using environment variables, as described in .

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Required environment variables

Using MySQL for authentication requires additional configuration parameters specified via environment variables. These variables collectively describe how Guacamole will connect to MySQL:

MYSQL_DATABASE

The name of the database to use for Guacamole authentication.

MYSQL_USER

The user that Guacamole will use to connect to MySQL.

MYSQL_PASSWORD

The password that Guacamole will provide when connecting to MySQL as MYSQL_USER.

If any required environment variables are omitted, you will receive an error message in the logs, and the image will stop. You will then need to recreate the container with the proper variables specified.

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PostgreSQL authentication

To use Guacamole with the PostgreSQL authentication backend, you will need either a Docker container running the postgres image, or network access to a working installation of PostgreSQL. The connection to PostgreSQL can be specified using either environment variables or a Docker link.

(initializing-guacamole-docker-postgresql)=

Initializing the PostgreSQL database

If your database is not already initialized with the Guacamole schema, you will need to do so prior to using Guacamole. A convenience script for generating the necessary SQL to do this is included in the Guacamole image.

To generate a SQL script which can be used to initialize a fresh PostgreSQL database as documented in :

$ docker run --rm guacamole/guacamole /opt/guacamole/bin/initdb.sh --postgresql > initdb.sql

Alternatively, you can use the SQL scripts included with the database authentication.

Once this script is generated, you must:

1. Create a database for Guacamole within PostgreSQL, such as guacamole_db.

2. Run the script on the newly-created database.

3. Create a user for Guacamole within PostgreSQL with access to the tables and sequences of this database, such as guacamole_user.

The process for doing this via the {command}psql and {command}createdb utilities included with PostgreSQL is documented in .

(guacamole-docker-postgresql-connecting)=

Connecting Guacamole to PostgreSQL

If your PostgreSQL database is provided by another Docker container, and you wish to use a Docker link to connect the Guacamole image to your database, the connection details are implied by the Docker link itself:

$ docker run --name some-guacamole \
    --link some-guacd:guacd        \
    --link some-postgres:postgres  \
    ...
    -d -p 8080:8080 guacamole/guacamole

If you are not using Docker to provide your PostgreSQL database, you will need to provide the network connection information yourself using additional environment variables:

POSTGRESQL_HOSTNAME

The hostname of the database to use for Guacamole authentication. This is required if you are not using Docker to provide your PostgreSQL database.

POSTGRESQL_PORT

The port that Guacamole should use when connecting to PostgreSQL. This environment variable is optional. If not provided, the standard PostgreSQL port of 5432 will be used.

The POSTGRESQL_HOSTNAME and, if necessary, POSTGRESQL_PORT environment variables can thus be used in place of a Docker link if using a Docker link is impossible or undesirable:

$ docker run --name some-guacamole     \
    --link some-guacd:guacd            \
    -e POSTGRESQL_HOSTNAME=172.17.42.1 \
    ...
    -d -p 8080:8080 guacamole/guacamole

Note that a Docker link to guacd (the --link some-guacd:guacd option above) is not required any more than a Docker link is required for PostgreSQL. The connection information for guacd can be specified using environment variables, as described in .

(guacamole-docker-postgresql-required-vars)=

Required environment variables

Using PostgreSQL for authentication requires additional configuration parameters specified via environment variables. These variables collectively describe how Guacamole will connect to PostgreSQL:

POSTGRESQL_DATABASE

The name of the database to use for Guacamole authentication.

POSTGRESQL_USER

The user that Guacamole will use to connect to PostgreSQL.

POSTGRESQL_PASSWORD

The password that Guacamole will provide when connecting to PostgreSQL as POSTGRESQL_USER.

If any required environment variables are omitted, you will receive an error message in the logs, and the image will stop. You will then need to recreate the container with the proper variables specified.

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Verifying the Guacamole install

Once the Guacamole image is running, Guacamole should be accessible at {samp}http://{HOSTNAME}:8080/guacamole/, where HOSTNAME is the hostname or address of the machine hosting Docker, and you should see a login screen. If using MySQL or PostgreSQL, the database initialization scripts will have created a default administrative user called "guacadmin" with the password "guacadmin". You should log in and change your password immediately. If using LDAP, you should be able to log in as any valid user within your LDAP directory.

If you cannot access Guacamole, or you do not see a login screen, check Docker's logs using the docker logs command to determine if something is wrong. Configuration parameters may have been given incorrectly, or the database may be improperly initialized:

$ docker logs some-guacamole