[TS-3650] Configuration variables should track their source

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.3.2, 6.0.0
• Component/s: Configuration
• Assignee: Alan M. Carroll
• Reporter: Alan M. Carroll
• Created: 31/May/15 20:36
• Updated: 04/Feb/16 18:55
• Resolved: 16/Jun/15 21:30

Description

A configuration variable can get its value from a variety of sources. It would be useful to be able to programmatically determine that source. At a minimum the ability to determine if a variable was set explicitly in a configuration file vs. using a built in default value would be very useful.

In addition this information should be made available to the administrator via traffic_ctl to aid in debugging.

The proposed values are

• DEFAULT - built in default, hard wired.
• FILE - read from a configuration file.
• API - set via an API of some sort (traffic_line etc.)
• CLUSTER - set via cluster configuration
• ENV - set from an environment variable

In addition the value INVALID will be defined to use for the internal API, primarily as a value to return if the requested variable doesn't exist (in which case none of the previous values are reasonable).

Update: Based on feedback the current values are

• DEFAULT - built in default, hard wired.
• EXPLICIT - set by the administrator
• ENV - set from an environment variable
• NULL - value does not exist, therefore has no source.

Issue Links

• blocks: TS-2861 traffic_ctl option to find differences from defaults
• blocks: TS-3669 ☂ Critical issues for v6.0.0 release
• is depended upon by: TS-3642 proxy.config.http.share_server_sessions not working