Automatic merge from submit-queue
Add pod condition PodScheduled to detect situation when scheduler tried to schedule a Pod, but failed
Set `PodSchedule` condition to `ConditionFalse` in `scheduleOne()` if scheduling failed and to `ConditionTrue` in `/bind` subresource.
Ref #24404
@mml (as it seems to be related to "why pending" effort)
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Before this change we have a mish-mash of ways to pass field names around for
error generation. Sometimes string fieldnames, sometimes .Prefix(), sometimes
neither, often wrong names or not indexed when it should be.
Instead of that mess, this is part one of a couple of commits that will make it
more strongly typed and hopefully encourage correct behavior. At least you
will have to think about field names, which is better than nothing.
It turned out to be really hard to do this incrementally.
For connect handlers that need to respond with a structured error or
structured object, pass an interface that hides the details of writing
an object to the response (error or runtime.Object).
Example use case:
Connect handler that accepts a body input stream, which it streams to a
pod, and then returns a structured object with info about the pod it
just created.
Not all clients and systems can support SPDY protocols. This commit adds
support for two new websocket protocols, one to handle streaming of pod
logs from a pod, and the other to allow exec to be tunneled over
websocket.
Browser support for chunked encoding is still poor, and web consoles
that wish to show pod logs may need to make compromises to display the
output. The /pods/<name>/log endpoint now supports websocket upgrade to
the 'binary.k8s.io' subprotocol, which sends chunks of logs as binary to
the client. Messages are written as logs are streamed from the container
daemon, so flushing should be unaffected.
Browser support for raw communication over SDPY is not possible, and
some languages lack libraries for it and HTTP/2. The Kubelet supports
upgrade to WebSocket instead of SPDY, and will multiplex STDOUT/IN/ERR
over websockets by prepending each binary message with a single byte
representing the channel (0 for IN, 1 for OUT, and 2 for ERR). Because
framing on WebSockets suffers from head-of-line blocking, clients and
other server code should ensure that no particular stream blocks. An
alternative subprotocol 'base64.channel.k8s.io' base64 encodes the body
and uses '0'-'9' to represent the channel for ease of use in browsers.
