[jira] [Created] (TS-1734) VMap functionality is missing a the vmap_config tool for bringing ip addresses up and down; but appears to be largely dead code

["John Kew (JIRA)" <ji...@apache.org>]

John Kew created TS-1734:
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             Summary: VMap functionality is missing a the vmap_config tool for bringing ip addresses up and down; but appears to be largely dead code
                 Key: TS-1734
                 URL: https://issues.apache.org/jira/browse/TS-1734
             Project: Traffic Server
          Issue Type: Bug
          Components: Management
            Reporter: John Kew


Virtual IPs were once managed such that within a cluster they
would automatically rebalance themselves between nodes by bringing
subinterfaces up and down. After ATS was open sourced the original
setuid tool, vip_config (or traffic_vip_config) was inadvertently
removed; but the code which depended on this tool was not cleaned
up.

Since modern deployments either do not use this tool at all
(because it was broken for a few years) and modern deployments also
have some central system for managing cluster state reliably, we
do not need VMap to implement some scheme for automatically
rebalancing the ips.

This patch keeps much of the code for detecting ip address conflicts
and for receiving the multicast messages from the cluster; but we
remove all instances where we either bring up/down an interface.

Deployments should manage this through external state systems.

Note: VIPs do not actually bind to the specific addresses in
vaddrs; this is just an operations convience to ensure that a
cluster has no ip conflicts or unmanaged vips. This feature becomes
even less useful. LocalManager.cc would have to be modified in some
way to set this up properly.

Note: The *right* thing to do here may be to recall that old tool and let
VMap do it's thing.

Note: Another *right* thing to do may be to remove VMap entirely, along
with the associated cluster messages. At least with this exiting changeset
we can detect ip address conflicts.

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