mikenye/picard

Docker container for MusicBrainz Picard

The GUI of the application is accessed through a modern web browser (no installation or configuration needed on client side) or via any VNC client.

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Picard is a cross-platform music tagger written in Python.

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This container is based on the absolutely fantastic jlesage/baseimage-gui. All the hard work has been done by them, and I shamelessly copied their README.md too. I've cut the README.md down quite a bit, for advanced usage I suggest you check out the README from jlesage/baseimage-gui.

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Quick Start

NOTE: The Docker command provided in this quick start is given as an example and parameters should be adjusted to your need.

Launch the Picard docker container with the following command:

docker run -d \
    --name=picard \
    -p 5800:5800 \
    -v /path/to/config:/config:rw \
    -v /path/to/music:/storage:rw \
    mikenye/picard

Where:

• /path/to/config: This is where the application stores its configuration, log and any files needing persistency.
• /path/to/music: This location contains music files for Picard to operate on.

Browse to http://your-host-ip:5800 to access the Picard GUI. Your music will be located under /storage.

Usage

docker run [-d] \
    --name=picard \
    [-e <VARIABLE_NAME>=<VALUE>]... \
    [-v <HOST_DIR>:<CONTAINER_DIR>[:PERMISSIONS]]... \
    [-p <HOST_PORT>:<CONTAINER_PORT>]... \
    mikenye/picard

Parameter	Description
-d	Run the container in background. If not set, the container runs in foreground.
-e	Pass an environment variable to the container. See the Environment Variables section for more details.
-v	Set a volume mapping (allows to share a folder/file between the host and the container). See the Data Volumes section for more details.
-p	Set a network port mapping (exposes an internal container port to the host). See the Ports section for more details.

Environment Variables

To customize some properties of the container, the following environment variables can be passed via the -e parameter (one for each variable). Value of this parameter has the format <VARIABLE_NAME>=<VALUE>.

Variable	Description	Default
USER_ID	ID of the user the application runs as. See User/Group IDs to better understand when this should be set.	1000
GROUP_ID	ID of the group the application runs as. See User/Group IDs to better understand when this should be set.	1000
SUP_GROUP_IDS	Comma-separated list of supplementary group IDs of the application.	(unset)
UMASK	Mask that controls how file permissions are set for newly created files. The value of the mask is in octal notation. By default, this variable is not set and the default umask of 022 is used, meaning that newly created files are readable by everyone, but only writable by the owner. See the following online umask calculator: http://wintelguy.com/umask-calc.pl	(unset)
TZ	[TimeZone] of the container. Timezone can also be set by mapping /etc/localtime between the host and the container.	Etc/UTC
KEEP_APP_RUNNING	When set to 1, the application will be automatically restarted if it crashes or if user quits it.	0
APP_NICENESS	Priority at which the application should run. A niceness value of -20 is the highest priority and 19 is the lowest priority. By default, niceness is not set, meaning that the default niceness of 0 is used. NOTE: A negative niceness (priority increase) requires additional permissions. In this case, the container should be run with the docker option --cap-add=SYS_NICE.	(unset)
CLEAN_TMP_DIR	When set to 1, all files in the /tmp directory are delete during the container startup.	1
DISPLAY_WIDTH	Width (in pixels) of the application's window.	1280
DISPLAY_HEIGHT	Height (in pixels) of the application's window.	768
SECURE_CONNECTION	When set to 1, an encrypted connection is used to access the application's GUI (either via web browser or VNC client). See the Security section for more details.	0
VNC_PASSWORD	Password needed to connect to the application's GUI. See the VNC Password section for more details.	(unset)
X11VNC_EXTRA_OPTS	Extra options to pass to the x11vnc server running in the Docker container. WARNING: For advanced users. Do not use unless you know what you are doing.	(unset)
ENABLE_CJK_FONT	When set to 1, open source computer font WenQuanYi Zen Hei is installed. This font contains a large range of Chinese/Japanese/Korean characters.	0

Data Volumes

The following table describes data volumes used by the container. The mappings are set via the -v parameter. Each mapping is specified with the following format: <HOST_DIR>:<CONTAINER_DIR>[:PERMISSIONS].

Container path	Permissions	Description
/config	rw	This is where the application stores its configuration, log and any files needing persistency.
/storage	ro/rw	This location contains files from your host that need to be accessible by the application. Should be 'rw' if you want Picard to re-tag/re-name your files.

Ports

Here is the list of ports used by the container. They can be mapped to the host via the -p parameter (one per port mapping). Each mapping is defined in the following format: <HOST_PORT>:<CONTAINER_PORT>. The port number inside the container cannot be changed, but you are free to use any port on the host side.

Port	Mapping to host	Description
5800	Mandatory	Port used to access the application's GUI via the web interface.
5900	Optional	Port used to access the application's GUI via the VNC protocol. Optional if no VNC client is used.
8000	Optional	Port used to access Picard's "browser integration" feature. Must be enabled in Picard's options (advanced > network, check "browser integration" and uncheck "listen only on localhost).

Changing Parameters of a Running Container

As seen, environment variables, volume mappings and port mappings are specified while creating the container.

The following steps describe the method used to add, remove or update parameter(s) of an existing container. The generic idea is to destroy and re-create the container:

1. Stop the container (if it is running):

docker stop picard

2. Remove the container:

docker rm picard

3. Create/start the container using the docker run command, by adjusting parameters as needed.

NOTE: Since all application's data is saved under the /config container folder, destroying and re-creating a container is not a problem: nothing is lost and the application comes back with the same state (as long as the mapping of the /config folder remains the same).

Docker Compose File

Here is an example of a docker-compose.yml file that can be used with Docker Compose.

Make sure to adjust according to your needs. Note that only mandatory network ports are part of the example.

version: '3'
services:
  picard:
    image: mikenye/picard:latest
    ports:
      - "5800:5800"
    volumes:
      - "/path/to/config:/config:rw"
      - "/path/to/music:/storage:rw"

Docker Image Update

If the system on which the container runs doesn't provide a way to easily update the Docker image, the following steps can be followed:

1. Fetch the latest image:

docker pull mikenye/picard

2. Stop the container:

docker stop picard

3. Remove the container:

docker rm picard

4. Start the container using the docker run command.

User/Group IDs

When using data volumes (-v flags), permissions issues can occur between the host and the container. For example, the user within the container may not exists on the host. This could prevent the host from properly accessing files and folders on the shared volume.

To avoid any problem, you can specify the user the application should run as.

This is done by passing the user ID and group ID to the container via the USER_ID and GROUP_ID environment variables.

To find the right IDs to use, issue the following command on the host, with the user owning the data volume on the host:

id <username>

Which gives an output like this one:

uid=1000(myuser) gid=1000(myuser) groups=1000(myuser),4(adm),24(cdrom),27(sudo),46(plugdev),113(lpadmin)

The value of uid (user ID) and gid (group ID) are the ones that you should be given the container.

Accessing the GUI

Assuming that container's ports are mapped to the same host's ports, the graphical interface of the application can be accessed via:

• A web browser:

http://<HOST IP ADDR>:5800

• Any VNC client:

<HOST IP ADDR>:5900

Security

By default, access to the application's GUI is done over an unencrypted connection (HTTP or VNC).

Secure connection can be enabled via the SECURE_CONNECTION environment variable. See the Environment Variables section for more details on how to set an environment variable.

When enabled, application's GUI is performed over an HTTPs connection when accessed with a browser. All HTTP accesses are automatically redirected to HTTPs.

When using a VNC client, the VNC connection is performed over SSL. Note that few VNC clients support this method. SSVNC is one of them.

Certificates

Here are the certificate files needed by the container. By default, when they are missing, self-signed certificates are generated and used. All files have PEM encoded, x509 certificates.

Container Path	Purpose	Content
/config/certs/vnc-server.pem	VNC connection encryption.	VNC server's private key and certificate, bundled with any root and intermediate certificates.
/config/certs/web-privkey.pem	HTTPs connection encryption.	Web server's private key.
/config/certs/web-fullchain.pem	HTTPs connection encryption.	Web server's certificate, bundled with any root and intermediate certificates.

NOTE: To prevent any certificate validity warnings/errors from the browser or VNC client, make sure to supply your own valid certificates.

NOTE: Certificate files are monitored and relevant daemons are automatically restarted when changes are detected.

VNC Password

To restrict access to your application, a password can be specified. This can be done via two methods:

• By using the VNC_PASSWORD environment variable.
• By creating a .vncpass_clear file at the root of the /config volume. This file should contains the password in clear-text. During the container startup, content of the file is obfuscated and moved to .vncpass.

The level of security provided by the VNC password depends on two things:

• The type of communication channel (encrypted/unencrypted).
• How secure access to the host is.

When using a VNC password, it is highly desirable to enable the secure connection to prevent sending the password in clear over an unencrypted channel.

ATTENTION: Password is limited to 8 characters. This limitation comes from the Remote Framebuffer Protocol RFC (see section 7.2.2). Any characters beyhond the limit are ignored.

Shell Access

To get shell access to a the running container, execute the following command:

docker exec -ti picard bash

Optional: Access to Optical Drive(s)

Picard can lookup CDs from an optical drive.

By default, a Docker container doesn't have access to host's devices. However, access to one or more device can be granted with the --device DEV parameter.

Optical drives usually have /dev/srX as device. For example, the first drive is /dev/sr0, the second /dev/sr1, and so on. To allow Picard to access the first drive, this parameter is needed:

--device /dev/sr0

To easily find devices of optical drives, start the container and look at its log for messages similar to these ones:

...
[cont-init.d] 95-check-optical-drive.sh: executing...
[cont-init.d] 95-check-optical-drive.sh: looking for usable optical drives...
[cont-init.d] 95-check-optical-drive.sh: found optical drive /dev/sr0, but it is not usable because is not exposed to the container.
[cont-init.d] 95-check-optical-drive.sh: no usable optical drive found.
[cont-init.d] 95-check-optical-drive.sh: exited 0.
...

Getting Help

Having troubles with the container or have questions? Please create a new issue.

I also have a Discord channel, feel free to join and converse.