This knob tells consul whether it should prefer the WAN address (if set)
when making service lookups in remote datacenters. This enables
reachability for remote services which are behind a NAT.
`AdvertiseAddrs` has been introduced as a configuration option, which
duplicates a few other options, namely `AdvertiseAddrWan`. We need to
use this value elsewhere, so rather than doing a precedence check every
time we need to access it, rectify the value of `AdvertiseAddrWan` to
match
Specifically:
* add Dnsmasq examples for reverse DNS for most of the RFC1918, 5735, and 6598 netblocks.
* Highlight some example options for dnsmasq that are probably of interest.
* Add a small section on reverse DNS testing
* Break out BINDs troubleshooting with Dnsmasq's troubleshooting
Not an exhaustive sweep, but should be helpful when introducing consul to new environments.
Introduce a low-level background connection expiration mechanism wherein connections will be recycled periodically based on the size and health of the cluster.
For the vast majority of consul users, this will mean an average connection age of 150s. For 10K node clusters it will take ~3min for clusters to rebalance their connections. In the pathological case for a 100K cluster where 99K clients are in the minority talking to 1x server it will take ~26min to rebalance all connections.
It's possibe for clients recovering from a parititon to become fixated on a single server until the server or agent is restarted. This is of particular interest to long-running environments with stable agents, where `allow_stale` is true, and partitions occur periodically.
Increase the max idle time for agents talking to servers from 30s to 127s in order to allow for the reuse of connections that are being initiated by cron.
127s was chosen as the first prime above 120s (arbitrarily chose to use a prime) with the intent of reusing connections who are used by once-a-minute cron(8) jobs *and* who use a 60s jitter window (e.g. in vixie cron job execution can drift by up to 59s per job, or 119s for a once-a-minute cron job).
Consolidate code duplication and tests into a single lib package. Most of these functions were from various **/util.go functions that couldn't be imported due to cyclic imports. The consul/lib package is intended to be a terminal node in an import DAG and a place to stash various consul-only helper functions. Pulled in hashicorp/go-uuid instead of consolidating UUID access.
Evan Gilman