Today `node.mode` and `node.local` serve almost the same purpose, they
are a shortcut for `discovery.type` and `transport.type`. If `node.local: true`
or `node.mode: local` is set elasticsearch will start in _local_ mode which means
only nodes within the same JVM are discovered and a non-network based transport
is used. The _local_ mode it only really used in tests or if nodes are embedded.
For both, embedding and tests explicit configuration via `discovery.type` and `transport.type`
should be preferred.
This change removes all the usage of these settings and by-default doesn't
configure a default transport implemenation since netty is now a module. Yet, to make
the user expericence flawless, plugins or modules can set a `http.type.default` and
`transport.type.default`. Plugins set this via `PluginService#additionalSettings()`
which enforces _set-once_ which prevents node startup if set multiple times. This means
that our distributions will just startup with netty transport since it's packaged as a
module unless `transport.type` or `http.transport.type` is explicitly set.
This change also found a bunch of bugs since several NamedWriteables were not registered if a
transport client is used. Now that we don't rely on the `node.mode` leniency which is inherited
instead of using explicit settings, `TransportClient` uses `AssertingLocalTransport` which detects these problems since it serializes all messages.
Closes#16234
This change adds a createComponents() method to Plugin implementations
which they can use to return already constructed componenents/services.
Eventually this should be just services ("components" don't really do
anything), but for now it allows any object so that preconstructed
instances by plugins can still be bound to guice. Over time we should
add basic services as arguments to this method, but for now I have left
it empty so as to not presume what is a necessary service.
The only reason for LifecycleComponent taking a generic type was so that
it could return that type on its start and stop methods. However, this
chaining has no practical necessity. Instead, start and stop can be
void, and a whole bunch of confusing generics disappear.
As discussed at https://github.com/elastic/elasticsearch-cloud-azure/issues/91#issuecomment-229113595, we know that the current `discovery-azure` plugin only works with Azure Classic VMs / Services (which is somehow Legacy now).
The proposal here is to rename `discovery-azure` to `discovery-azure-classic` in case some users are using it.
And deprecate it for 5.0.
Closes#19144.
Simon Willnauer
Ryan Ernst
David Pilato