Cluster version is the min major.minor of all members in
the etcd cluster. Cluster version is set to the min version
that a etcd member is compatible with when first bootstrapp.
During a rolling upgrades, the cluster version will be updated
automatically.
For example:
```
Cluster [a:1, b:1 ,c:1] -> clusterVersion 1
update a -> 2, b -> 2
after a detection
Cluster [a:2, b:2 ,c:1] -> clusterVersion 1, since c is still 1
update c -> 2
after a detection
Cluster [a:2, b:2 ,c:2] -> clusterVersion 2
```
The API/raft component can utilize clusterVersion to determine if
it can accept a client request or a raft RPC.
We choose polling rather than pushing since we want to use the same
logic for cluster version detection and (TODO) cluster version checking.
Before a member actually joins a etcd cluster, it should check the version
of the cluster. Push does not work since the other members cannot push
version info to it before it actually joins. Moreover, we do not want our
raft RPC system (which is doing the heartbeat pushing) to coordinate cluster version.
Before this PR, people can set listen-client-urls without setting
advertise-client-urls, and leaves advertise-client-urls as default
localhost value. The client libraries which sync the cluster info
fetch wrong advertise-client-urls and cannot connect to the cluster.
This PR avoids this case and provides better UX.
On the other hand, this change is safe because people always want to set
advertise-client-urls if listen-client-urls is set. The default localhost
advertise url cannot be accessed from the outside, and should always be
set except that etcd is bootstrapped with no flag.
The original process is stopping etcd only when pipeline message finds itself
has been removed. After this PR, stream dial has this functionality too.
It helps fast etcd stop, which doesn't need to wait for stream break to
fall back to pipeline, and wait for election timeout to send out message
to detect self removal.
A bit was missing from the documentation on disaster recovery, the reset
of the advertised peer urls for the node recovered from backup. Without
that, any subsequent server joining the cluster would not be able to
speak to the first node.
When removing a member, etcdserver might return 410 that indicates
the member has been removed. To client, 410 is a vaild response since
the client might do internal retry.
Add remotes to rafthttp, who help newly joined members catch up the
progress of the cluster. It supports basic message sending to remote, and
has no stream connection for simplicity. remotes will not be used
after the latest peers have been added into rafthttp.
Subcommits:
decouple root and security enable/disable
create root role
prefix matching
godep: bump go-etcd to include credentials
add godep for speakeasy and auth entry parsing
appropriate errors for security enable/disable
WIP adding to etcd/client all the security client methods
add guest access
minor ui return tweaks
revert client changes
respond to comments, log more security operations
fix major ensure() bug, add better UX
block recursive access
fix some boneheaded mistakes
fix integration test
last comments
fix up security_api.md
philips nits
fix docs
Decoder should return error for any broken block including the
one that only contains the length field. We should change io.EOF
to io.ErrUnexpectedEOF before return the error.
It is more reasonable to init the variable before passing it as an
argument.
It fixes a bug that etcdserver may panic on server stats when processing
a message from rafthttp streamReader before server stats is initialized
in server.Start().
