Hey Sebastian,
I am sorry that you took my comment about errors between chair and
keyboard completely wrong: it was definitely not pointed at you! What I
meant is that users will often misconfigure (I've been there many
times), and their experience will suffer. Therefore I am not concerned
about any 'smart' logic we write (regardless of number of lines of
code), but about any complexity required from, or offered to the users.
Rest of the comments inline...
On 12/13/2018 02:45 PM, Sebastian Laskawiec wrote:
On Thu, Dec 13, 2018 at 10:23 AM Radim Vansa <rvansa(a)redhat.com
<mailto:rvansa@redhat.com>> wrote:
On 12/12/2018 03:30 PM, Sebastian Laskawiec wrote:
> On Tue, Dec 11, 2018 at 11:13 AM Radim Vansa <rvansa(a)redhat.com
<mailto:rvansa@redhat.com>
> <mailto:rvansa@redhat.com <mailto:rvansa@redhat.com>>> wrote:
>
> I dislike having any logic based on the port number in some
range;
> it's
> not common that behaviour would change if you set port to 9xxx
> instead
> of 8xxx.
>
>
> That's not a problem with my approach, since you can always
manually
> turn the setting off or on. Here's how you do it:
> ConfigurationBuilder cb = ...
> cb.singlePort(SinglePortMode.ENABLED); // other options:
DISABLED and AUTO
Adding config options is just a way to avoid solving problems :)
Remember the famous quote: "Less knobs!"
It depends on the problem in my opinion. I always preferred to have
more configuration options with good defaults.
>
>
> Is there an (up-to-date) design doc?
>
>
> No, this is just a proposal. I was hoping that you guys like it and
> then, with some thumbs up, I could update the design doc.
>
> Here's the most up-to-date version in case you were looking for it:
>
https://github.com/infinispan/infinispan-designs/blob/master/Single_port....
>
>
> I don't fully follow, but if there's a problem in the HTTP
> handlers you
> can add a PING-detecting handler below...?
>
>
> Thanks for the hint Radim!
>
> Inspired by your idea I went ahead and checked how OpenShift Router
> behaves. It turns out that it responds HTTP 400 if you throw Hotrod
> bytes at it and then drops the connection.
I understand that the reason to have Hot Rod PING sent as the first
operation is to make sure that a new client that tries to connect
to old
server won't confuse the server, is that correct? Or is there
anything else?
Not only. We (Tristan and I when we were discussing it) wanted to
introduce the smallest possible hit on a default scenario - a Hotrod
client connecting to Infinispan without Single Port. If we mess up
this scenario, we might quickly get into all sorts of problem
(including performance).
I'll assume that a new server will handle both Hot Rod PING and HTTP
request correctly without any prelude, and old one will be ok with
Hot
Rod PING only. I don't really understand the:
I'm not sure if I follow. The Single Port functionality for non-TLS
scenario requires only REST interface. Hotrod is optional. We upgrade
to Hotrod using HTTP/1.1 Upgrade procedure (see RFC 7230 [1]). This
essentially means, that you need to send an HTTP request in order to
upgrade to another protocol (such as Hotrod) and reuse the same TCP
connection.
Okay, then my assumption was incorrect. That means that single-port
server and non-single-port server are incompatible because neither can
accept other's initial request :-/
It seems that Hot Rod and HTTP communication is easily distinguishable
with first few bytes: could we enhance single-port to be able to handle
Hot Rod PING immediately without the HTTP Upgrade to accommodate older
clients? Then we could run single-port all the time and everyone wins.
Btw., I assume that we can't handle both TLS and non-TLS connections on
same port either, is that correct? Usually webservers can't be
configured to handle both HTTP and HTTPS on the same port - is there any
difference here?
So as you can see, the Single Port can not speak both protocols, HTTP
and Hotrod, at the same time. It requires sending an HTTP request with
proper header, and then upgrading to Hotrod. The reason it has been
implemented this way is to support Reverse Proxies (like HAProxy in
the OpenShift Router, but of course there are more of them). As I
mentioned in my last email, the HA proxy immediately responds with
HTTP 400 if you throw binary payload at it. That's why we need to
follow the HTTP upgrade procedure - to get through it.
[1]
https://svn.tools.ietf.org/svn/wg/httpbis/specs/rfc7230.html#header.upgrade
> implementing it this way seems a bit "inconvenient" to me. The Ping
> Operation uses 60s timeout, which seems to be a good fit as a
default.
> Unfortunately, for the Single Port functionality, this means
we'd need
> to wait 60s until we try to send HTTP request and do an upgrade
why would you wait for 60 seconds? If the other end is Infinispan
server
(old or new), you just send HR PING and you're done, server will
proceed
correctly. If the other server is a router, you'll get a response
starting with 'HTTP': in Hot Rod protocol that would be parsed as
opCode
0x54 which is illegal response code (the id belongs to
COUNTER_RESET_REQUEST). At this point you know that this
connection is
going to be closed, and can immediately start another one (is
*this* the
problem?) that will send a HTTP request with Upgrade header.
This is correct. However, you silently assumed that the HTTP Server
(either our own Infinispan REST Server or any type of Reverse Proxy
we're passing through) will respond with an HTTP message (either 4xx
or 5xx) when receiving binary traffic. At this point I know that
HAProxy does that, and the same does Envoy (as you told us in the
bottom of this email). Infinispan REST server just ignores such a
request.
So it is safe to assume, that all Reverse Proxies will return an HTTP
message when we send a bunch of bytes at it? If yes, than we need to
correct the REST implementation (that should not be too hard) and kick
the Single Port in, when a Hotrod client receives a HTTP message back
when sending PING. But then, if some Reverse Proxy between the server
and client does something different (ignoring such a request as our
Infinispan REST server does now, or simply refuse a connection, or
anything else) we won't be able to upgrade the connection.
That's a valid point - the spec says that it SHOULD [1] respond with 400
but it is not 100% (buggy proxies are to be expected on the internet).
We should probably correct the REST server...
[1]
https://tools.ietf.org/html/rfc7230#section-3.1.1
My proposal is to set the Single Port support on the client, so that
the client starts the communication with HTTP message (and not the
Hotrod PING). Doing it this way, allows us to forget about all those
crazy situations with Reverse Proxies. The key point is that we never
throw raw bytes at them. In my opinion this can save us a lot of headache.
I am starting to think that we really should start the communication
with HTTP message, and this shouldn't be a separate config property
(single-port) but based on Hot Rod version.
So, to be honest, I can implement it whichever way you prefer. My
personal feeling is that an additional setting on the Hotrod client is
much safer bet (at least for now).
@Tristan, @Ryan, I think you guys also have some experience in this
matter. I would be very interested in hearing your opinion as well.
> I also realized, there's one more moving bit - TCP Keepalive.
Luckily,
> we can control this setting over configuration in our
standalone.xml.
> However, it is perfectly legal what I've seen in Netty (do not
respond
> and keep the connection alive assuming that TCP Keepalive is set
to true).
>
> The more I think about this, the more I'm convinced that the Single
> Port support should be explicitly set in the client (or inferred
from
> the configuration). I do not know how Nginx, Linkerd or Envoy
behaves
> in situation when they expect HTTP and get a stream of bytes.
Relying
> on this partially unknown behavior for doing our upgrade procedure
> doesn't seem right to me.
FYI Envoy does the same, send 400 and terminate the connection.
Ok, so it behaves the same as HA Proxy.
>
> Just in case you're worried about the additional logic on the
client
> side - it's super small. Really, only 13 lines including
brackets ;)
>
https://github.com/infinispan/infinispan/pull/6133/files#diff-684a10c939f...
I am not worried about any logic in the client code, I am worried
about
logic between chair and keyboard.
Ouch! That was pretty rude, Radim. Words like that make me feel very
uncomfortable and actually offend me. I would like to ask you to stick
to the technical aspect of this thread and do not go personal.
As we've known each other for a pretty long time, I will pretend I
didn't see this and I just read "please have a look what I just wrote,
maybe you will reconsider your implementation?".
See the top, please, and my apologies if you took the above as an
offense. TBH I haven't even checked the implementation, and I am far
from judging it.
Radim
R.
>
> Radim
>
> On 12/10/2018 03:27 PM, Sebastian Laskawiec wrote:
> > Hey guys,
> >
> > During Infinispan F2F, I had a short discussion with
Tristan on
> Single
> > Port client-side implementation. Back then, we agreed that the
> client
> > should always send a Hotrod Ping request and if won't get any
> response
> > (or get some HTTP content back), it will try to upgrade to the
> Hotrod
> > protocol using Single Port.
> >
> > I've been playing with the implementation for a while, and
> > implementing it this way seems a bit "inconvenient" to me.
The Ping
> > Operation uses 60s timeout, which seems to be a good fit as a
> default.
> > Unfortunately, for the Single Port functionality, this means
> we'd need
> > to wait 60s until we try to send HTTP request and do an
upgrade.
> Also,
> > another problematic part is in Netty's HTTP handlers
> > (HttpObjectDecoder, HttpServerCodec and
ByteToMessageDecoder). When
> > those classes fail to decode a message (REST expects HTTP
rather
> than
> > a stream of bytes specific to Hotrod protocol), they just
ignore it
> > and keep the channel in active state (which also makes
sense for
> > HTTP/1.1 and HTTP/2).
> >
> > At this point, my intuition tells, that this doesn't look
right and
> > seems to be a over-complicated. The whole HTTP upgrade idea
> seems to
> > work the other way around, use HTTP as a fallback and then
> upgrade to
> > other protocols. Forcing it to work a bit differently
requires some
> > more effort.
> >
> > What if we preserved the Single Port setting in the client
> > configuration but implemented it as an enum with the following
> values
> > - true/false/auto. In automatic mode, the client would
check if the
> > server port is set to 8\d{1,3} (this covers 80, 8080,
8081, 8443
> and
> > friends). If that is true, we'd try to follow HTTP Upgrade
> procedure.
> > This looks very simple and I think this might actually
work. Please
> > note, that we need the single port setting in the client
> configuration
> > to cover some corner cases like the Single Port exposed on
> different
> > port (like 4444) or Hot Rod exposed on port that starts
with 8.
> >
> > What do you think about such simplification?
> >
> > Thanks,
> > Sebastian
> >
> >
> >
> >
> > _______________________________________________
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>
>
> --
> Radim Vansa <rvansa(a)redhat.com <mailto:rvansa@redhat.com>
<mailto:rvansa@redhat.com <mailto:rvansa@redhat.com>>>
> JBoss Performance Team
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