* Params improvements to Cluster Health API wait for shards
Previously, the cluster health API used a strictly numeric value
for `wait_for_active_shards`. However, with the introduction of
ActiveShardCount and the removal of write consistency level for
replication operations, `wait_for_active_shards` is used for
write operations to represent values for ActiveShardCount. This
commit moves the cluster health API's usage of `wait_for_active_shards`
to be consistent with its usage in the write operation APIs.
This commit also changes `wait_for_relocating_shards` from a
numeric value to a simple boolean value `wait_for_no_relocating_shards`
to set whether the cluster health operation should wait for
all relocating shards to complete relocation.
* Addresses code review comments
* Don't be lenient if `wait_for_relocating_shards` is set
This should make them easier to read and adds them to the test suite
I changed the example from a two node cluster to a single node cluster
because that is what we have running in the integration tests. It is also
what a user just starting out is likely to see so I think that is ok.
The number of current pending tasks is useful to detect and overloaded master. This commit adds it to the cluster health API. The complete list can be retrieved from the dedicated pending tasks API.
It also adds rest tests for the cluster health variants.
Closes#9877
The description of the timeout parameter was worded misleadingly; it implied that the API would wait until the cluster reached the desired level and then stayed at that level for the timeout. I've tweaked the sentence to remove the risk of confusion.