Display Builder Web Runtime (DBWR)¶

The Display Builder Web Runtime (DBWR) is a service that serves Phoebus .bob displays as web pages.

Enabling DBWR¶

To enable the DBWR service, add this to your configuration:

dbwr.nix¶

{
  services.dbwr = {
    enable = true;
    openFirewall = true;
  };
}

This configuration starts a Tomcat server on port 8080 by default, with the DBWR and PV Web Socket (PVWS) web apps configured.

The services.dbwr NixOS module makes those applications available at:

http://host-addr:8080/dbwr/
http://host-addr:8080/pvws/

Configuring the address list¶

The address list is configured by default using the environment.epics module. See the EPICS environment guide for more information.

Configuring DBWR and PVWS¶

PVWS and DBWR are configured through environment variables, which you can pass through the services.dbwr.settings option.

For more information about available environment variables, see the DBWR README and PVWS README.

Enabling write access¶

Caution

If your PVs are restricted by Channel Access or PV Access access security, it’s recommended to put DBWR and PVWS behind authentication via a reverse proxy.

Since the PVWS service handles PV writes, the user seen by access security rules will be the Tomcat user.

To enable write access from the web interface, set the PV_WRITE_SUPPORT setting to true:

dbwr.nix¶

{
  services.dbwr = {
    # ...
    settings.PV_WRITE_SUPPORT = true;
  };
}

Serve displays¶

DBWR doesn’t provide displays by itself but loads .bob files from a given “remote” URL.

To serve .bob files for DBWR, you can start an nginx web server.

From the NixOS configuration¶

Serve .bob files from the NixOS configuration for DBWR¶

{
  services.nginx = {
    enable = true;
    # Serve the `bobs` directory next to this `.nix` file,
    # from the URL `http://localhost/`
    virtualHosts."localhost".locations."/".root = ./bobs;
  };
}

This configuration copies the ./bobs directory into the Nix store and serves the .bob files from it.

Depending on your situation, you can change "localhost" to your domain name and "/" to the path where you want to serve the .bob displays.

From another directory on the system¶

If you don’t want to manage your .bob files from the NixOS configuration but prefer a folder on the local system instead, set the folder as an absolute path and put quotes around it:

Serve .bob files from a local folder for DBWR¶

{
  services.nginx = {
    enable = true;
    # Serve the local `/var/www/bobs` directory from the system
    # from the URL `http://localhost/`
    #
    # Note the quotes around the folder:
    virtualHosts."localhost".locations."/".root = "/var/www/bobs";
  };
}

Depending on your situation, you can change "localhost" to your domain name and "/" to the path where you want to serve the .bob displays.