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From "Michele Sciabarra" <>
Subject Re: A plan to (re) implement OpenWhisk on top of Knative
Date Mon, 20 May 2019 15:00:02 GMT
Ok great, I see the discussion is starting to bring ideas.

Yes my goal is basically to run existing actions in Knative, create and invoke. And possibile
retain the ability of an action to invoke another action.

I understand the different way they expose services, so I am rethinking the idea of using
a "work-alike" path. 

If it is needed we can add it with an ingress but it may be not necessary in the initial implementation.

Also I checked a bit ML and discussions and I see this Tekton thing that should be the preferred

Not sure if I understand the relation with the current Build API documented in the website.
Is Tekton "compatible" or it has a different API?

  Michele Sciabarra

----- Original message -----
From: "Markus Thömmes" <>
Subject: Re: A plan to (re) implement OpenWhisk on top of Knative
Date: Monday, May 20, 2019 4:50 PM

Good discussion, thanks!

Can we try to define what the desired end-goal is here? I'm a bit unclear
what resembling the OpenWhisk API actually buys us.

To me, the desired end-state would be to run OpenWhisk actions as-is on a
Knative cluster (similar to OpenFaaS' and Azure's integration). There's no
good way for us to provide the full API without spinning up a control plane
and we can only handle so much via the CLI. So to me, the end-goal looks

1. *wsk action create* actually doing all the pieces necessary to run a
piece of code on Knative.
2. *wsk action invoke* doing some HTTP call under the hood to "invoke" that
action. The action should be reachable via a sensible URL. If we really
want to keep the API surface (as I said, I'm dubious here) we can also do
that via ingress level abstractions (like VirtualService).


Am Mo., 20. Mai 2019 um 15:33 Uhr schrieb Martin Henke <

> > On 20. May 2019, at 14:55, Michele Sciabarra <>
> wrote:
> >
> >> Michele,
> >
> >> I like the idea to make the ActionLoop based runtimes to be runnable on
> Knative.
> >>
> >> My thoughts on this:
> >> - I second Markus concern to implement the invocation API onto Knative
> instead of just using Knative service syntax.
> > Can you elaborate this? I do not understand.
> Knative service syntax:    https://<service(in our case =
> action)>.<namespace>.<host>/
> OW invocation https://
> <api-host>/api/v1/namespaces/<namespace>/actions/<action>
> (I personally so no worth in inventing a distinct API for OW images, but
> as said I would see that as a valid optional feature)
> >
> >> - I would have concerns to make it dependent on Gloo which is kind of a
> minority choice for Knative load balancing
> > I do not think it will be hard to setup a test also using Istio, I do
> not want to be limited to Gloo.
> I just wanted to prevent that Gloo gets a “official” prerequisite for an
> “official” OW on Knative flow.
> It is of course free to you to use what ever you want to do in your
> prototype.
> > - In my opinion the goal should be to have some uniform behaviour for
> ActionLoop based runtimes
> >> and other ones like the adapted NodeJS runtimes demonstrated by Matt
> and Priti
> > As much as I can tell the current implementation is just the building
> and exposing the "/init" and "/run" but I can be wrong.
> > The build can be of course reused, so it continues the effort. For the
> frontend, from the documentation I think Matt wants to add a proxy, while I
> would like to implemeent the "invocation" straight in the runtime. This is
> open to discussion, but of course it is better to reach an agreement.
> Also in the work of Priti and Matt the invocation goes directly to the
> runtime. The action code is either passed with the call (not yet tested by
> me) or set via environment variable in the docker build.
> >
> >> - As Knative Build seems be on a dead end I would propose to target
> Tekton as the build system (which developed as kind of >successor out of
> Knative)
> >
> > If Knative build is dead then it would be a bit unfair that they change
> it as the scope of the Knative project!
> > It looks like the goal is  to setup some standards! And I would be very
> disappointed to know that.
> Tekton evolved out of Knative Build (or more correct out of Knative
> Pipelines) but is very similar to the Knative build.
> Flows can easily be ported from one to the other,
> If we target Tekton build we would target the platform were the Knative
> build team is focusing on.
> But again feel free to use whatever platform for your prototype work.
> > At this stage the build is the more interesting thing, and it could be
> even imported in main openwhisk to speed up deployment.
> > I have already baked it in the ActionLoop runtimes (with precompilation).
> > Also if we use Tekton, where is the Knative standard then? What is the
> point? We can build our own system instead of "Knativizing" it...
> >
> >> Maybe it would be a good solution to tackle two things independently.
> >> 1) Design and implement a common protocol of building, running and
> calling OW runtimes on Knative
> >> 2) Implement the OW invocation API on top of Knative as an additional
> option for those who have the need to expose it.
> >
> > On this, for my personal approach at building things, I want something
> that works and it is complete and useful. A "MVP”.
> Cool. Just go on.
> > So I do not plan to split the effort. Version 0.1 must be a minimal
> working subset of OpenWhisk on Knative.
> > Because otherwise there will be incomplete useless inusable pieces
> around (see for example kwsk).
> >
> > It does not mean that things cannot be modular, nor that everyone must
> but to me "openwhisk-knative" must be a single repo with all the pieces to
> make something where you can download is and deploy in a kubernetes cluster
> and be able to deploy simple actions. When this works, we can improve
> incrementally and split it but keeping it working.
> >
> >> I would looking forward to work with you on the first work item.
> > Great  but I see now more details to discuss before we can start. Most
> notably I need to understand how I can build on top of Mark and Priti work
> and continue their work. ANd I can even probably recover some of the code
> of kwsk as they implemented some openwhisk api, that I want now in the
> runtime.
> >
> I do not want to stop you in any way. My hope is that the action loop
> runtimes and the “other ones” do expose the same behaviour when being
> called. So that the users is not surprised when calling different actions
> in different languages.
> And behaving the same way might also mean to adapt the “other languages”
> to the same behaviour as the action loop based ones.
> They just should be uniform to be used.
> When your prototype is accessible it would be a good point of time to
> discuss this.
> As said I very much like your effort.
> >
> >> On 20. May 2019, at 08:55, Michele Sciabarra <>
> wrote:
> >>
> >>
> >>>> I have an idea for implementing a prototype of OpenWhisk on top of
> Knative.
> >>>> My basic ideas are: do not use any proxy, forwarding or adapter:
> extend
> >>>> the runtime to support the REST call and expose them as ingress. And
> use a
> >>>> wrapper on top of `kubectl` to generate all the needed components.
> >>
> >>> Does this tie into the work that Matt was doing to the runtimes to make
> >>> them runnable on Knative? Is this lined up with that at all?
> >> Actually yes. He suggested I can investigate how to migrate ActionLoop
> to port many other languages to Knative.
> >> Also he recommended I add my idea and this is what I am doing. Current
> code is, if I am not wrong, a Knative build of the nodejs runtime.
> >>
> >> There has been a number of attempts and proposal to move forward
> OpenWhisk. My idea that to succeed we need something small but that just
> works. This is my idea to be able to implement in the shorter time frame
> possible an actual subset of OpenWhisk that works and it is truly built on
> top of Knative. So I am putting the thing a bit further than Matt work.
> >>
> >>
> >>>> My goal is to have a functional work-alike of OpenWhisk built on top
> of
> >>>> Knative, using ActionLoop as a foundation. I will extend ActionLoop
> >>>> support the required REST calls of OpenWhisk.
> >>>
> >>>> I also want to create tool, I will call `wskn`. This tool will
> initially
> >>>> just a python script, a wrapper on top of `kubectl` as it will
> generate
> >>>> kubernetes descriptors.
> >>> Why not build this into "wsk" itself? The Azure Functions CLI as an
> example
> >>> supports multiple deployment types like this in one CLI.
> >>
> >> When it will works, yes, of course. But to start, what I really need is
> a prototype that can generate kubernetes descripttors to feed to kubectl,
> so a  simplee, quick and ditry, separate tool (that I will keep together
> the runtime) is all I need for now.
> >>
> >>>>
> >>>> It will support initially just the the action creation and
> invocation, and
> >>>> only synchronous (blocking) behaviour, as all the request will go
> straight
> >>>> to the runtimes. Hopefully also a subset of `package` and
> `activation`.
> >>>> Again triggers, rules, asynchronous for later.
> >>>>
> >>>> The idea is that you will be able to create actions and web actions
> that
> >>>> can run existing OpenWhisk actions, at least those with blocking
> behaviour
> >>>> that run with ActionLoop (Go, Java, Python, PHP, Swift, Rust, Ruby,
> >>>> Crystal...)
> >>>>
> >>>> Implementation.
> >>>> ==============
> >>>>
> >>>> This is how I plan to implement it.
> >>>>
> >>>> At this stage I want to use just Knative Serving and Knative Build,
> using
> >>>> Gloo for the ingress part. I also plan to install a local Docker
> registry
> >>>> Kubernetes registry, so we do not have to use DockerHub for
> everything. All
> >>>> of this can be done with existing command line tools in a few minutes
> in
> >>>> any running Kubernetes deployment.
> >>>>
> >>
> >>> Why specifying Gloo here? Do you need anything specific from Gloo
> itself?
> >>> If not I'd propose to just keep it on a Knative Serving API surface
> level.
> >> I want to build it on top of Knative serving, full stop. Currently,
> installing Gloo is pretty easy and is more  lightweight than Istio so I
> will use it for my  first implementation.
> >>
> >>>>
> >>>> When I create an action, it will use Knative build that will work
> roughly
> >>>> in this way:
> >>>>
> >>>> - create a configmap with the action code
> >>>> - build the actin using ActionLoop precompilation feature that will
> return
> >>>> a zip file including all the needed to run the action
> >>>> - create a new docker image extending the runtime with the new zip,
> using
> >>>> Kaanico
> >>>> - push the image in the local registry
> >>> This feels like a fairly heavyweight process, we should be able to
> come up
> >>> with a way to circumvent zipping entirely. Maybe the runtime can detect
> >>> that the unzipped content is already there and skip the unzip step?
> >>
> >> Actually this is my first idea of how to use Knative build. And is not
> complicated: when I create the action, a run a build that includes Kanico.
> I generate a Dockerfile on the fly. The docker file uses the action runtime
> that already know how to compile a script. And then I save an image. I
> already implemented un "autoinit" so just launching the image will give a
> runtime ready to run that execute an action already compiled.
> >>
> >>
> >>> I'm fairly hesitant on the usage of a ConfigMap for storing the action
> >>> code. It's all stored in the in-cluster etcd instance and it has a
> limit of
> >>> 1M. This is at most a stop-gap solution to provide a PoC I think. Any
> ideas
> >>> on how to "productize" this?
> >>
> >> ConfigMap can be mounted as files, so it is an easy way  to feed an
> action to a build. It is just an easy way to feed the action code to the
> Build.
> >>
> >> My initial constraint is that I want just to generate Kubernetes
> descriptors to feed to kubectl.
> >> Of course in the long run I can add some "file upload" storage.
> >>
> >> If I could to this file upload when invoking a build it could ideal as
> I do not have to store anything anywhere, just process the code and
> generate a single layer to execute actions to be store in the registry.
> >> I will investigate better this area, I understand your concern.
> >>
> >>>
> >>>> At this point you can run the action. ActionLoop will be extended to
> >>>> support invocations in the format
> >>>> "/v1/namespaces/namespace/actions/package/action".
> >>> Why bother reimplementing this exact path? To obtain API compatibility
> with
> >>> OpenWhisk as it is today?
> >>
> >> I want to implement a subset of the OpenWhisk API on top of Knative
> serving.
> >> Knative serving already does the scaling and routing, so what we need
> are the "endpoints" to invoke actions.
> >>
> >> Since I do not want to add additional components, not at the first
> stage. Just knative serve and build, the runtime and a controller script,
> the runtime is the natural place where to "handle" the API invocations,
> since Knative only generates the URL but not anything else.  If I
> understood well, Matt is adding a proxy. I do not want to add a proxy, just
> add to the runtime the ability to respond to "API like" calls, at least
> those regarding action invocation.
> >>
> >>>> It will do all the decoding required to invoke the action with the
> >>>> expected paramenters (straight invocation thrhoug the actinloop
> protocol,
> >>>> not proxies).
> >>> Does this mean moving all of the Controller's "smartness" about
> incoming
> >>> and outgoing HTTP requests (see the whole WebActions for example)?
> >>
> >> At least decoding web actions in the runtime, yes. Knative serving
> already has routing and proxying.
> >> So a true implementation on top of Knative requires IHMO this
> sacrifice. Unless there is a way to keep the controller in a "Knative"
> compatible way. Open to suggestions here.
> >>
> >>> Each action will then be exposed using an ingress with its specific
> >>> invocation path.
> >>>
> >>> If the community agrees with this plan, I would create a repo
> >>> `incubator-openwhisk-knative` to work on it.
> >>>
> >>> Thoughts?

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