[MESOS-3340] Command-line flags should take precedence over OS Env variables

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.24.0
• Fix Version/s: 0.25.0
• Component/s: stout
• Labels: mesosphere tech-debt
• Target Version/s: 0.25.0
• Story Points: 2
• Assignee: Klaus Ma
• Reporter: Marco Massenzio
• Shepherd: Michael Park
• Created: 31/Aug/15 18:06
• Updated: 26/Nov/18 12:22
• Resolved: 26/Nov/18 12:22

Description

Currently, it appears that re-defining a flag on the command-line that was already defined via a OS Env var (MESOS_*) causes the Master to fail with a not very helpful message.

For example, if one has MESOS_QUORUM defined, this happens:

$ ./mesos-master --zk=zk://192.168.1.4/mesos --quorum=1 --hostname=192.168.1.4 --ip=192.168.1.4
Duplicate flag 'quorum' on command line

which is not very helpful.

Ideally, we would parse the flags with a "well-known" priority (command-line first, environment last) - but at the very least, the error message should be more helpful in explaining what the issue is.