There is a JIRA live for the network resilience feature that I mentioned previously.
The design document <https://docs.google.com/document/d/1iGVwxeHp57qogwfdodCh9b32P2_kOQaJZ2GDo7j36fI/edit?usp=sharing> (also copied into the JIRA) has essentially converged except for two points. These include: 1) Artem Chernatsky has pointed out an opportunity to factor our port sets in the configuration syntax as well as an interesting interaction with the existing behavior where the current servers already listen to the specified ports on all NICs. This semantics of this interaction between configuration options need to be specified rigorously, but this doesn't appear to impact code complexity much, nor introduce any real difficulties. 2) Alex Shraer seems to feel that there is a strong interaction between this issue <https://issues.apache.org/jira/browse/ZOOKEEPER-3188> and a proposed refactorization of the configuration file syntax (mentioned in a comment in 3166, but apparently doesn't have an independent issue). In particular, he seems to think that the syntax refactorization is a blocker for the network resilience. My own feeling is that there is some interaction, but there is no strong ordering between the two issues if the implementors of this issue are willing to commit to supporting any consensus syntax change that is adopted. Essentially, there can be an additional issue filed which is blocked by both the syntax change issue and 3188 (network resilience) to support any new syntax. The work for 3188 needs to support the old syntax in any case so that we can backport changes to 3.4. Other open issues that are affected by configuration syntax change include 2534 <https://issues.apache.org/jira/browse/ZOOKEEPER-2534>, 2531 <https://issues.apache.org/jira/browse/ZOOKEEPER-2531>, 195 <https://issues.apache.org/jira/browse/ZOOKEEPER-195>, and 2225 <https://issues.apache.org/jira/browse/ZOOKEEPER-2225>. None of these has any serious impact other than the fact that configuration needs to be abstracted as part of any change. Some appear to be quite old and may have already been solved or made moot. My own feeling is that pushing for this issue (3188) to include a change to the configuration syntax as well as the core network resilience feature proposed is an unacceptable increase in scope. I have filed a new tracking issue <https://issues.apache.org/jira/browse/ZOOKEEPER-3189> (3189) capturing the intended rework after a change in configuration syntax, but I can't find anywhere that the configuration change is captured in a issue to add the dependency. I also see no particular way that configuration syntax change (as desirable as it might be) blocks this feature. I would love to hear other opinions. I, myself, think that the "support resilience under new syntax when available" approach
