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Perforce 2010.2: System Administrator's Guide



Chapter 11
What is the Broker?
The Perforce Broker (P4Broker) enables you to implement local policies in your Perforce environment by allowing you to restrict the commands that can be executed, or redirect specific commands to alternate Perforce servers.
The Perforce Broker is a server process that mediates between Perforce client applications and Perforce servers, including proxy servers. For example, Perforce client applications can connect to a proxy server that connects to the broker, which then connects to a Perforce server. Or, Perforce client applications can connect to a broker configured to redirect reporting-related commands to a read-only replica server, while passing other commands through to a master server.
From the perspective of the end user, the broker is transparent: users connect to a Perforce Broker just as they would connect to any other Perforce Server.
System requirements
To use the Perforce Broker, you must have:
The Perforce Broker is designed to run on a host that lies close to the Perforce Server (P4D), preferably on the same machine.
Installing the Broker
To install P4Broker, do the following:
1.
Download the p4broker executable from the Perforce Web site,
2.
Copy it to a suitable directory on the host (such as /usr/local/bin), and ensure that the binary is executable:
chmod +x p4broker
Running the Broker
After you have created your configuration file, start the Perforce Broker from the command line by issuing the the following command:
p4broker -c config_file -d
Alternatively, you can set P4BROKEROPTIONS before launching the broker and use it to specify the broker configuration file (or other flags) to use.
For example, on Unix:
and on Windows:
The Perforce Broker reads the specified broker configuration file, and on Unix platforms the -d flag causes the Perforce Broker to detach itself from the controlling terminal and run in the background.
To configure the Perforce Broker to start automatically, create a startup script that sets P4BROKEROPTIONS runs the appropriate p4broker command. On Windows systems, you can also P4BROKEROPTIONS and run the broker as a service.
P4Broker flags
-c file
Specify a configuration file.
Overrides P4BROKEROPTIONS setting.
-v subsystem=level
Set server trace flags. Overrides value P4DEBUG setting. Default is null.
Configuring the Broker
P4Broker is controlled by a broker configuration file. The broker configuration file is a text file that contains rules for
Specifying which commands that individual users can use
Defining commands that are to be redirected to specified server.
To generate a sample broker configuration file, issue the following command:
p4broker -C > p4broker.conf
You can edit the newly-created p4broker.conf file to specify your requirements.
Format of broker configuration files
A broker configuration file contains three sections:
Command handler specifications: specify how individual commands should be handled; in the absence of a command handler for any given command, the Perforce Broker will permit the execution of the command.
Global settings
The following settings apply to all operations you specify for the broker.
The default Perforce Server (P4D) to which commands are sent unless overridden by other settings in the configuration file.
target = host:port;
The address on which the Perforce Broker listens for commands from Perforce client applications.
listen = [host:]port;
The home directory for the Perforce Broker. Other paths specified in the broker configuration file must be relative to this location.
The name of your Perforce Administrator. This information is displayed to the user in certain error messages.
An email address at which users can contact their Perforce Administrator.
admin-email = admin@example.com;
The telephone number of the Perforce Administrator.
The redirection mode to use: selective or pedantic.
In selective mode, redirection is permitted within a session until one command has been executed against the default (target) server. From then on, all commands within that session run against the default server and are not redirected.
In pedantic mode, all requests for redirection are honored.
Command handler specifications
Command handlers enable you to specify the how broker responds to different commands issued by different users from within different environments. When users run commands, the Perforce Broker searches for matching command handlers and uses the first match found. If no command handler matches the user's command, the command is forwarded to the target Perforce Server for normal processing.
Due to ticket handling issues, the p4 login and p4 logout commands cannot be caught by a command handler.
The general syntax of a command handler specification is outlined in the sample broker.conf:
command: commandpattern
  # Conditions for the command to meet; (optional)
  flags       = required flags;
  user        = required user;
  workspace   = required client workspace;
  prog        = required Perforce client application;
  version     = required version of client application;
  # What to do with matching commands (required)
  action      =  pass | reject | redirect | filter | respond ;
  # How to go about it
  destination = altserver;       # Required for action = redirect
  execute     = filter program;  # Required for action = filter
  message     = message;         # Required for action = reject and
                                  # action = respond. Otherwise optional
The commandpattern parameter can include the "*" wildcard. For example, a commandpattern of "user*" matches both the "p4 user" and "p4 users" commands.
The following table describes the parameters in detail.
Defines how the Perforce Broker handles the specified commands. Valid values are: pass, reject, redirect, filter, or respond
For redirected commands, the name of the alternate server to which the commands are redirected. The destination must be the name of a previously-defined alternate server.
This feature enables you to specify different handling for the same p4 command, depending on which flags the user specifies. Note that only single character flags may be specified here. Multi-character flags, and flags that take arguments should be handled by a filter program.
The Perforce client application through which the user issued the command. This feature enables you to handle commands on a per-application basis.
For example, the following command handler prevents user joe from invoking p4 submit from the buildonly client workspace.
command: submit
user = joe;
workspace = buildonly;
action = reject;
message = "Submit failed: Please do not submit from this workspace."
Filter Programs
When the action for a command handler is filter, the Perforce Broker executes the program or script specified by the execute parameter and performs the action returned by the program. Filter programs enable you to enforce policies beyond the capabilities provided by the broker configuration file.
The Perforce Broker invokes the filter program by passing command details to the program's standard input in the following format:
Your filter program must read this data from stdin before performing any additional processing, regardless of whether the script requires the data. If the filter script does not read the data from stdin, "broken pipe" errors can occur, and the broker rejects the user's command.
Your filter program must respond to the Broker on standard output (stdout) with data in one of the four following formats:
action: PASS
message: a message for the user (optional)
action: REJECT
message: a message for the user (required)
action: REDIRECT
altserver: (an alternate server name)
message: a message for the user (optional)
action: RESPOND
message: a message for the user (required)
The values for the action are case-sensitive.
The action keyword is always required and tells the Broker how to respond to the user's request. The available actions are:
Run the user's command unchanged.
A message for the user is optional.
Reject the user's command.
A message for the user is required.
If the filter program returns any response other than something complying with the four message formats above, the user's command is rejected. If errors occur during the execution of your filter script code cause the broker to reject the user's command, the broker returns an error message.
Alternate server definitions
The Perforce Broker can direct user requests to an alternate server to reduce the load on the default server. These alternate servers must be replicas of the target server.
To set up and configure a replica server, see Chapter 10, Perforce Replication. The broker works with both metadata-only replicas and with replicas that have access to both metadata and versioned files.
There is no limit to the number of alternate servers you can define in a broker configuration file.
The syntax for specifying an alternate server is as follows:
altserver name { target=host:port }
The name assigned to the alternate server is used in command handler specifications. See Command handler specifications.
Configuring alternate servers to work with central authorization servers
Alternate servers require users to authenticate themselves when they run commands. For this reason, the Perforce Broker must be used in conjunction with a central authorization server (P4AUTH) and Perforce Servers at version 2007.2 or later. For more information about setting up a central authorization server, see Centralized authorization server.
When used with a central authorization server, a single p4 login request can create a ticket that is valid for the user across all servers in the Perforce Broker's configuration, enabling the user to log in once. The Perforce Broker assumes that a ticket granted by the target server is valid across all alternate servers.
If the target server in the broker configuration file is a central authorization server, the value assigned to the target parameter must precisely match the setting of P4AUTH on the alternate server machine(s). Similarly, if an alternate sever defined in the broker configuration file is used as the central authorization server, the value assigned to the target parameter for the alternate server must match the setting of P4AUTH on the other server machine(s).
 


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Perforce 2010.2: System Administrator's Guide
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