Configuring TLJH with tljh-config

tljh-config is the commandline program used to make configuration changes to TLJH.

Running tljh-config

You can run tljh-config in two ways:

  1. From inside a terminal in JupyterHub while logged in as an admin user. This method is recommended.
  2. By directly calling /opt/tljh/hub/bin/tljh-config as root when logged in to the server via other means (such as SSH). This is an advanced use case, and not covered much in this guide.

Set / Unset a configuration property

TLJH’s configuration is organized in a nested tree structure. You can set a particular property with the following command:

sudo tljh-config set <property-path> <value>

where:

  1. <property-path> is a dot-separated path to the property you want to set.
  2. <value> is the value you want to set the property to.

For example, to set the password for the DummyAuthenticator, you need to set the auth.DummyAuthenticator.password property. You would do so with the following:

sudo tljh-config set auth.DummyAuthenticator.password mypassword

This can only set string and numerical properties, not lists.

To unset a configuration property you can use the following command:

sudo tljh-config unset <property-path>

Unsetting a configuration property removes the property from the configuration file. If what you want is only to change the property’s value, you should use set and overwrite it with the desired value.

Some of the existing <property-path> are listed below by categories:

Authentication

Use auth.type to determine authenticator to use. All parameters in the config under auth.{auth.type} will be passed straight to the authenticators themselves.

Ports

Use http.port and https.port to set the ports that TLJH will listen on, which are 80 and 443 by default. However, if you change these, note that TLJH does a lot of other things to the system (with user accounts and sudo rules primarily) that might break security assumptions your other applications have, so use with extreme caution.

sudo tljh-config set http.port 8080
sudo tljh-config set https.port 8443
sudo tljh-config reload proxy

User Lists

  • users.allowed takes in usernames to whitelist
  • users.banned takes in usernames to blacklist
  • users.admin takes in usernames to designate as admins

User Server Limits

  • limits.memory Specifies the maximum memory that can be used by each individual user. By default there is no memory limit. The limit can be specified as an absolute byte value. You can use the suffixes K, M, G or T to mean Kilobyte, Megabyte, Gigabyte or Terabyte respectively. Setting it to None disables memory limits.

    sudo tljh-config set limits.memory 4G

    Even if you want individual users to use as much memory as possible, it is still good practice to set a memory limit of 80-90% of total physical memory. This prevents one user from being able to single handedly take down the machine accidentally by OOMing it.

  • limits.cpu A float representing the total CPU-cores each user can use. By default there is no CPU limit. 1 represents one full CPU, 4 represents 4 full CPUs, 0.5 represents half of one CPU, etc. This value is ultimately converted to a percentage and rounded down to the nearest integer percentage, i.e. 1.5 is converted to 150%, 0.125 is converted to 12%, etc. Setting it to None disables CPU limits.

    sudo tljh-config set limits.cpu 2

User Environment

user_environment.default_app Set default application users are launched into. Currently can be set to the following values jupyterlab or nteract

sudo tljh-config set user_environment.default_app jupyterlab

Extra User Groups

users.extra_user_groups is a configuration option that can be used to automatically add a user to a specific group. By default, there are no extra groups defined.

Users can be “paired” with the desired, existing groups using:

  • tljh-config set, if only one user is to be added to the desired group:
tljh-config set users.extra_user_groups.group1 user1
  • tljh-config add-item, if multiple users are to be added to the group:
tljh-config add-item users.extra_user_groups.group1 user1
tljh-config add-item users.extra_user_groups.group1 user2

View current configuration

To see the current configuration, you can run the following command:

sudo tljh-config show

This will print the current configuration of your TLJH. This is very useful when asking for support!

Reloading JupyterHub to apply configuration

After modifying the configuration, you need to reload JupyterHub for it to take effect. You can do so with:

sudo tljh-config reload

This should not affect any running users. The JupyterHub will be restarted and loaded with the new configuration.

Advanced: config.yaml

tljh-config is a simple program that modifies the contents of the config.yaml file located at /opt/tljh/config/config.yaml. tljh-config is the recommended method of editing / viewing configuration since editing YAML by hand in a terminal text editor is a large source of errors.