This gets a number of improvements:
* Fixed a missing case where gossip would stop flowing to dead nodes for a short while.
* Uses the go-sockaddr library to look for private IP addresses, which prefers non-loopback
private addresses over loopback ones when trying to automatically determine the advertise address.
* Properly seeds Go's random number generator using the seed library.
* Serf snapshots no longer have the executable bit set on thie file.
* Updates Raft library to get new snapshot/restore API.
* Basic backup and restore working, but need some cleanup.
* Breaks out a snapshot module and adds a SHA256 integrity check.
* Adds snapshot ACL and fills in some missing comments.
* Require a consistent read for snapshots.
* Make sure snapshot works if ACLs aren't enabled.
* Adds a bit of package documentation.
* Returns an empty response from restore to avoid EOF errors.
* Adds API client support for snapshots.
* Makes internal file names match on-disk file snapshots.
* Adds DC and token coverage for snapshot API test.
* Adds missing documentation.
* Adds a unit test for the snapshot client endpoint.
* Moves the connection pool out of the client for easier testing.
* Fixes an incidental issue in the prepared query unit test.
I realized I had two servers in bootstrap mode so this wasn't a good setup.
* Adds a half close to the TCP stream and fixes panic on error.
* Adds client and endpoint tests for snapshots.
* Moves the pool back into the snapshot RPC client.
* Adds a TLS test and fixes half-closes for TLS connections.
* Tweaks some comments.
* Adds a low-level snapshot test.
This is independent of Consul so we can pull this out into a library
later if we want to.
* Cleans up snapshot and archive and completes archive tests.
* Sends a clear error for snapshot operations in dev mode.
Snapshots require the Raft snapshots to be readable, which isn't supported
in dev mode. Send a clear error instead of a deep-down Raft one.
* Adds docs for the snapshot endpoint.
* Adds a stale mode and index feedback for snapshot saves.
This gives folks a way to extract data even if the cluster has no
leader.
* Changes the internal format of a snapshot from zip to tgz.
* Pulls in Raft fix to cancel inflight before a restore.
* Pulls in new Raft restore interface.
* Adds metadata to snapshot saves and a verify function.
* Adds basic save and restore snapshot CLI commands.
* Gets rid of tarball extensions and adds restore message.
* Fixes an incidental bad link in the KV docs.
* Adds documentation for the snapshot CLI commands.
* Scuttle any request body when a snapshot is saved.
* Fixes archive unit test error message check.
* Allows for nil output writers in snapshot RPC handlers.
* Renames hash list Decode to DecodeAndVerify.
* Closes the client connection for snapshot ops.
* Lowers timeout for restore ops.
* Updates Raft vendor to get new Restore signature and integrates with Consul.
* Bounces the leader's internal state when we do a restore.
