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Jacob Marble edited this page Aug 5, 2016 · 16 revisions


Good question. You may not need to configure the connector at all. Consider these lists of pros and cons before proceeding:

Running the Connector without a config file:

  • computer printers => GCP printers
  • clients
  • Chrome/ChromeOS
  • Android
  • print via the local subnet
  • no Internet connection required
  • good for homes and small offices

Running the Connector with a config file:

  • computer printers => GCP printers
  • clients
  • Chrome/ChromeOS
  • Android
  • Windows
  • third-party clients that don't support local printing
  • print, manage sharing, manage print jobs via the Google Cloud Print service
  • reliable Internet connection required
  • good for schools and enterprise

Get started

Run the following command to create a config file called gcp-cups-connector.config.json:

$ gcp-connector-util -init

Newer builds will fail; remove the hyphen:

$ gcp-connector-util init

On Windows, create gcp-windows-connector.config.json:

gcp-connector-util.exe init

To use the config file, run the connector. The -config-filename flag is optional; without it, the connector will look for a file named gcp-cups-connector.config.json:

$ gcp-cups-connector -config-filename gcp-cups-connector.config.json

Config file parameters

File Format

The Connector config file is in JSON format, so it looks like this:

  "string_name": "value",
  "boolean_name": true,
  "integer_name": 123,
  "list_name": [


option description
cups_max_connections Limits the quantity of connections to the CUPS server.
cups_connect_timeout How much patience to apply when opening a new connection to the CUPS server.
cups_job_queue_size Limits the quantity of jobs queued in the CUPS server. Excess jobs wait in the connector queue.
cups_printer_poll_interval The interval between checking the CUPS server for printer changes (state, PPD). When the connector is on the same host as the CUPS server, this value can safely be very small, say 10s, to keep printer state updated in the Google Cloud Print cloud service.
cups_printer_attributes CUPS printer attributes are converted to CDD tags. This can be used to remotely monitor a CUPS printer attribute via Google Cloud Print. The default list of attributes are required for the CUPS Connector to function properly.
cups_vendor_ppd_options CUPS PPD options to enable, listed by PPD MainKeyword. By default, the connector looks for options that are common. To enable all PPD options, simply list "all" instead of each MainKeyword (be careful, some printers dozens of PPD options that don't translate well).
cups_job_full_username Whether to use the full username ( instead of joe) to create CUPS jobs.
cups_ignore_raw_printers Raw printers are ignored by default; change that here.
cups_ignore_class_printers Classes are ignored by default.
copy_printer_info_to_display_name Use the CUPS printer-info printer attribute as the Google Cloud Print display name. Otherwise, the printer-name attribute is used.
prefix_job_id_to_job_title Adds the Google Cloud Print job ID to the beginning of the CUPS print job title. This can be useful for debugging.
display_name_prefix Adds a prefix to the GCP printer name.
printer_blacklist Names of printers to not share with GCP.
printer_whitelist Names of printers to only share with GCP. If empty or absent, then all printers discovered, minus those named in printer_blacklist are shared.
monitor_socket_filename The tool gcp-cups-connector-util -monitor uses this socket to query the connector. The default value places this file in /tmp but a more traditional location is /var/spool.
local_printing_enable Enable local printing, where the print client communicates directly with the CUPS Connector. "Local printing" is also known as "Privet" or "GCP 2.0".
cloud_printing_enable Enable "cloud" printing, where the print client communicates with the CUPS Connector via the Google Cloud Print cloud service. This is what most people think of when they talk about Google Cloud Print.
log_file_name Name of the log file.
log_file_max_megabytes Maximum log file size.
log_max_files Maximum quantity of log files.
log_level Threshold for minimum log severity. Can be one of "FATAL", "ERROR", "WARNING", "INFO", "DEBUG"

Options unique to cloud printing

These are only used for "cloud" printing, ie non-local printing.

option description
xmpp_jid XMPP JID, the unique identifier of this connector on the XMPP connection. XMPP is an open chat protocol, used by the Google Cloud Print cloud service to notify the connector of a new print job.
robot_refresh_token This token is used to authenticate HTTP requests and the XMPP conversation, to the Google Cloud Print cloud service. This token is like a password for the connector, so it's important that you treat it as such.
user_refresh_token This token is used to authenticate automatic sharing requests to the Google Cloud Print cloud service. This token is a bit more sensitive than robot_refresh_token, as it can be used outside of the context of the connector.
share_scope The group or user to automatically share printers with, indicated with an email address.
proxy_name This is the name given to one instance of the connector. If you only have one connector, then the name can be anything. If you have more than one connector, be sure to give each connector a unique name.
xmpp_server The FQDN for Google's XMPP service. Do not change.
xmpp_port The port number for Google's XMPP service. The default value is 443, which should work with any firewall.
gcp_xmpp_ping_timeout The CUPS Connector pings the XMPP server periodically. An error state is detected when this timeout is exceeded.
gcp_xmpp_ping_interval_default Interval between XMPP pings.
gcp_base_url The base URL to access the Google Cloud Print cloud service. Do not change.
gcp_oauth_client_id Identifies the CUPS Connector to the Google Cloud Print cloud service. Do not change.
gcp_oauth_client_secret Goes along with the Client ID. Not actually secret. Do not change.
gcp_oauth_auth_url Google's OAuth2 authentication URL. Do not change.
gcp_oauth_token_url Google's OAuth2 token URL. Do not change.
gcp_max_concurrent_downloads Limits the maximum quantity of job payloads (normally PDF file) to be downloaded at once. If you have a very busy print server, and have a fast Internet connection, then it might make sense to increase this value.
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