* Add cache types for catalog/services and health/services and basic test that caching works
* Support non-blocking cache types with Cache-Control semantics.
* Update API docs to include caching info for every endpoint.
* Comment updates per PR feedback.
* Add note on caching to the 10,000 foot view on the architecture page to make the new data path more clear.
* Document prepared query staleness quirk and force all background requests to AllowStale so we can spread service discovery load across servers.
In a real agent the `cache` instance is alive until the agent shuts down so this is not a real leak in production, however in out test suite, every testAgent that is started and stops leaks goroutines that never get cleaned up which accumulate consuming CPU and memory through subsequent test in the `agent` package which doesn't help our test flakiness.
This adds a Close method that doesn't invalidate or clean up the cache, and still allows concurrent blocking queries to run (for up to 10 mins which might still affect tests). But at least it doesn't maintain them forever with background refresh and an expiry watcher routine.
It would be nice to cancel any outstanding blocking requests as well when we close but that requires much more invasive surgery right into our RPC protocol since we don't have a way to cancel requests currently.
Unscientifically this seems to make tests pass a bit quicker and more reliably locally but I can't really be sure of that!
If you provide an invalid HTTP configuration consul will still start again instead of failing. But if you do so the build-in proxy won't be able to start which you might need for connect.
Fixes: #4578
Prior to this fix if there was an error binding to ports for the DNS servers the error would be swallowed by the gated log writer and never output. This fix propagates the DNS server errors back to the shell with a multierror.
Fixes#4515
This just slightly refactors the logic to only attempt to set the serf wan reconnect timeout when the rest of the serf wan settings are configured - thus avoiding a segfault.
Also change how loadProxies works. Now it will load all persisted proxies into a map, then when loading config file proxies will look up the previous proxy token in that map.
- Dev mode assumed no persistence of services although proxy state is persisted which caused proxies to be killed on startup as their services were no longer registered. Fixed.
- Didn't snapshot the ProxyID which meant that proxies were adopted OK from snapshot but failed to restart if they died since there was no proxyID in the ENV on restart
- Dev mode with no persistence just kills all proxies on shutdown since it can't recover them later
- Naming things
This turns out to have a lot more subtelty than we accounted for. The test suite is especially prone to races now we can only poll the child and many extra levels of indirectoin are needed to correctly run daemon process without it becoming a Zombie.
I ran this test suite in a loop with parallel enabled to verify for races (-race doesn't find any as they are logical inter-process ones not actual data races). I made it through ~50 runs before hitting an error due to timing which is much better than before. I want to go back and see if we can do better though. Just getting this up.
Paul Banks