[infinispan-dev] Single Port Client
Radim Vansa
rvansa at redhat.com
Fri Dec 14 08:26:35 EST 2018
On 12/14/2018 11:49 AM, Sebastian Laskawiec wrote:
>
>
> On Thu, Dec 13, 2018 at 4:42 PM Radim Vansa <rvansa at redhat.com
> <mailto:rvansa at redhat.com>> wrote:
>
> 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.
>
>
> No problem, Radim. I was a little but surprised by that "left jab"
> coming from nowhere ;) Emails are such a bad media of communication
> when it comes to situations like this. In normal F2F communication
> that would never happen. I'm also sorry for all the confusion...
>
> This actually made me thinking, maybe it's the right time to do a
> small 15 min meeting to discuss this F2F? @Tristan, @Ryan, @Galder -
> would you also be interested? I'll prepare some slides to show you the
> main pain points.
>
>
> 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 at redhat.com
> <mailto:rvansa at redhat.com>
> > <mailto:rvansa at redhat.com <mailto:rvansa at 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 at redhat.com <mailto:rvansa at redhat.com>
> > <mailto:rvansa at redhat.com <mailto:rvansa at redhat.com>>
> > > <mailto:rvansa at redhat.com <mailto:rvansa at redhat.com>
> <mailto:rvansa at redhat.com <mailto:rvansa at 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.adoc
> > >
> > >
> > > 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.
>
>
> Yes, that's absolutely doable, but it doesn't solve the problem,
> because there might be some Reverse Proxies on the way (such as an OCP
> Router, Nginx or anything else). Those proxies might mess up with our
> upgrade flow (as you mentioned below, there can be buggy proxies on
> the way). The main problem is that we don't know (we can assume but we
> are not 100% certain), how the Reverse Proxy will behave if we throw
> binary protocol at it.
Handling Hot Rod on single port in the first case would be there to
allow old clients connecting to new server. If you point an old client
to some proxy instead of Hot Rod server, you're out of luck anyway.
>
> Also, if we always start with Single Port turned on, we'll add
> additional round trip (send HTTP with upgrade request, wait for
> response, then switch to Hotrod). This adds some delay and I'm not
> sure we should do it. If we wanted to consider this, I would need to
> get Tristan's "green stamp" on it. But I have serious doubts
We don't need extra roundtrip. Client sends HTTP Upgrade: Hot Rod,
server responds with 101 Switching protocols and immediately follows
with Hot Rod Ping response. The client will expect that. Any extra
parameters we currently send in PING could be added to the initial HTTP
Upgrade request as extra headers. We start every connection with PING
anyway so this would not add any latency.
>
> 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?
>
>
> The encrypted use case is soooo much easier. The protocol negotiation
> happen during TLS handshake. Once it's finished and connection is
> established (so after the handshake is done), you already know about
> the communication protocol you will be using. If we wanted to support
> only encrypted use cases, the implementation would in 10-20 lines of code.
>
> Frankly, I expect people to be using unencrypted use cases when
> developing features and encrypted use cases on production. That's my
> gut feeling how this feature will be used.
I had rather the use case when you have a non-encrypted *and* encrypted
service exposed on the *same* port. Yes, ALPN can do a lot for you for free.
>
> >
> > 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...
>
>
> Thanks for double checking. Yes, I believe we should. Let me test it a
> little bit more and create proper JIRAs.
>
>
> [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.
>
>
> I also through about this but finally, I rejected the idea. The main
> reasoning behind is this:
> - We mess up with our default execution flow - hotrod client
> connecting to a hotrod server. If there's any bug there we miss during
> testing, there is a high chance we get a critical bug in return. And
> since Infinispan is not my primary responsibility at the moment, I'm
> worried that this will cause troubles and additional pressure to the team.
1) old client connecting to new server (without proxy) would work, since
single port would support Hot-Rod-prior-knowledge.
2) old client connecting through proxy is already screwed
3) new client connecting to old server must already set the protocol
version manually (no change)
4) new client connecting to new server would fly nicely (just a few more
bytes sent, but no latency), through proxy or not
> - We perform additional round trip when initiating a connection (as I
> explained before in this email).
Not necessary, explained.
> - The default server configuration would be more complicated
> (especially the endpoint configuration).
I would think that with removing the options it would actually become
*less* complicated. Since we're working on ServerNG, the configuration
could actually declare that on one place, something like:
<single-port-connector socket-binding="foo" security-realm="..."
cache-container="clustered" >
I admit this needs to list all the use cases but the above is as complex
as declaring Hot Rod-only connector and involves them all.
> - The final argument (probably the least important) is that we don't
> support Websockets and Memcached in Single Port. So the configuration
> wouldn't be symmetric. It's probably a nitpick, but I don't like it.
Websockets are dropped. Memcached... the request starts with 0x80 so
it's distinguishable to our 0xA0 and HTTP's 'H' = 0x54 - let's put it
under the umbrella, too.
Radim
>
>
> >
> > 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-684a10c939f31fcfef0f5f48d469393aR618
> >
> > 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.
>
>
> All good Radim, no worries! And thanks for all the stuff you're doing!
>
>
> 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
> > > >
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > infinispan-dev mailing list
> > > > infinispan-dev at lists.jboss.org
> <mailto:infinispan-dev at lists.jboss.org>
> > <mailto:infinispan-dev at lists.jboss.org
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> <mailto:infinispan-dev at lists.jboss.org>
> > <mailto:infinispan-dev at lists.jboss.org
> <mailto:infinispan-dev at lists.jboss.org>>>
> > > > https://lists.jboss.org/mailman/listinfo/infinispan-dev
> > >
> > >
> > > --
> > > Radim Vansa <rvansa at redhat.com
> <mailto:rvansa at redhat.com> <mailto:rvansa at redhat.com
> <mailto:rvansa at redhat.com>>
> > <mailto:rvansa at redhat.com <mailto:rvansa at redhat.com>
> <mailto:rvansa at redhat.com <mailto:rvansa at redhat.com>>>>
> > > JBoss Performance Team
> > >
> > > _______________________________________________
> > > infinispan-dev mailing list
> > > infinispan-dev at lists.jboss.org
> <mailto:infinispan-dev at lists.jboss.org>
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> <mailto:infinispan-dev at lists.jboss.org>
> > <mailto:infinispan-dev at lists.jboss.org
> <mailto:infinispan-dev at lists.jboss.org>>>
> > > https://lists.jboss.org/mailman/listinfo/infinispan-dev
> > >
> > >
> > >
> > > _______________________________________________
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> >
> >
> > --
> > Radim Vansa <rvansa at redhat.com <mailto:rvansa at redhat.com>
> <mailto:rvansa at redhat.com <mailto:rvansa at redhat.com>>>
> > JBoss Performance Team
> >
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> >
> >
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>
> --
> Radim Vansa <rvansa at redhat.com <mailto:rvansa at redhat.com>>
> JBoss Performance Team
>
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--
Radim Vansa <rvansa at redhat.com>
JBoss Performance Team
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