Kubernetes backend and docker images

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Kubernetes backend and docker images

Marcelo Vanzin
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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Re: Kubernetes backend and docker images

liyinan926
This is neat. With some code cleanup and as long as users can still use custom driver/executor/init-container images if they want to, I think this is great to have. I don't think there's a particular reason why having a single image wouldn't work. Thanks for doing this!

On Fri, Jan 5, 2018 at 5:06 PM, Marcelo Vanzin <[hidden email]> wrote:
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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Re: Kubernetes backend and docker images

Mridul Muralidharan
In reply to this post by Marcelo Vanzin

We should definitely clean this up and make it the default, nicely done Marcelo !

Thanks,
Mridul 

On Fri, Jan 5, 2018 at 5:06 PM Marcelo Vanzin <[hidden email]> wrote:
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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Re: Kubernetes backend and docker images

Jeff Zhang

Awesome, less is better

Mridul Muralidharan <[hidden email]>于2018年1月6日周六 上午11:54写道:

We should definitely clean this up and make it the default, nicely done Marcelo !

Thanks,
Mridul 

On Fri, Jan 5, 2018 at 5:06 PM Marcelo Vanzin <[hidden email]> wrote:
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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Re: Kubernetes backend and docker images

Jiang Xingbo
In reply to this post by Marcelo Vanzin
Agree it should be nice to have this simplification, and users can still create their custom images by copy/modifying the default one.
Thanks for bring this out Marcelo!

2018-01-05 17:06 GMT-08:00 Marcelo Vanzin <[hidden email]>:
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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Re: Kubernetes backend and docker images

Felix Cheung
+1

Thanks for taking on this.
That was my feedback on one of the long comment thread as well, I think we should have one docker image instead of 3 (also pending in the fork are python and R variant, we should consider having one that we official release instead of 9, for example)



From: 蒋星博 <[hidden email]>
Sent: Friday, January 5, 2018 10:57:53 PM
To: Marcelo Vanzin
Cc: dev
Subject: Re: Kubernetes backend and docker images
 
Agree it should be nice to have this simplification, and users can still create their custom images by copy/modifying the default one.
Thanks for bring this out Marcelo!

2018-01-05 17:06 GMT-08:00 Marcelo Vanzin <[hidden email]>:
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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Re: Kubernetes backend and docker images

Anirudh Ramanathan-3
+1

We discussed some alternatives early on - including using a single dockerfile and different spec.container.command and spec.container.args from the Kubernetes driver/executor specification (which override entrypoint in docker). No reason that won't work also - except that it reduced the transparency of what was being invoked in the driver/executor/init by hiding it in the actual backend code.  

Putting it into a single entrypoint file and branching let's us realize the best of both worlds I think. This is an elegant solution, thanks Marcelo. 

On Jan 6, 2018 10:01 AM, "Felix Cheung" <[hidden email]> wrote:
+1

Thanks for taking on this.
That was my feedback on one of the long comment thread as well, I think we should have one docker image instead of 3 (also pending in the fork are python and R variant, we should consider having one that we official release instead of 9, for example)



From: 蒋星博 <[hidden email]>
Sent: Friday, January 5, 2018 10:57:53 PM
To: Marcelo Vanzin
Cc: dev
Subject: Re: Kubernetes backend and docker images
 
Agree it should be nice to have this simplification, and users can still create their custom images by copy/modifying the default one.
Thanks for bring this out Marcelo!

2018-01-05 17:06 GMT-08:00 Marcelo Vanzin <[hidden email]>:
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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Re: Kubernetes backend and docker images

Anirudh Ramanathan-3
+matt +tim
For reference - here's our previous thread on this dockerfile unification problem - https://github.com/apache-spark-on-k8s/spark/pull/60
I think this approach should be acceptable from both the customization and visibility perspectives.


On Mon, Jan 8, 2018 at 9:40 AM, Anirudh Ramanathan <[hidden email]> wrote:
+1

We discussed some alternatives early on - including using a single dockerfile and different spec.container.command and spec.container.args from the Kubernetes driver/executor specification (which override entrypoint in docker). No reason that won't work also - except that it reduced the transparency of what was being invoked in the driver/executor/init by hiding it in the actual backend code.  

Putting it into a single entrypoint file and branching let's us realize the best of both worlds I think. This is an elegant solution, thanks Marcelo. 

On Jan 6, 2018 10:01 AM, "Felix Cheung" <[hidden email]> wrote:
+1

Thanks for taking on this.
That was my feedback on one of the long comment thread as well, I think we should have one docker image instead of 3 (also pending in the fork are python and R variant, we should consider having one that we official release instead of 9, for example)



From: 蒋星博 <[hidden email]>
Sent: Friday, January 5, 2018 10:57:53 PM
To: Marcelo Vanzin
Cc: dev
Subject: Re: Kubernetes backend and docker images
 
Agree it should be nice to have this simplification, and users can still create their custom images by copy/modifying the default one.
Thanks for bring this out Marcelo!

2018-01-05 17:06 GMT-08:00 Marcelo Vanzin <[hidden email]>:
Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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--
Anirudh Ramanathan
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Re: Kubernetes backend and docker images

Matt Cheah

We would still want images to be able to be uniquely specified for the driver vs. the executors. For example, not all of the libraries required on the driver may be required on the executors, so the user would want to specify a different custom driver image from their custom executor image.

 

But the idea of the entry point script that can switch based on environment variables makes sense.

 

I do think we want separate Python and R images, because Python and R come with non-trivial extra baggage that can make the images a lot bigger and slower to download for Scala-only users.

 

From: Anirudh Ramanathan <[hidden email]>
Date: Monday, January 8, 2018 at 9:48 AM
To: Felix Cheung <[hidden email]>
Cc:
蒋星博 <[hidden email]>, Marcelo Vanzin <[hidden email]>, dev <[hidden email]>, Matt Cheah <[hidden email]>, Timothy Chen <[hidden email]>
Subject: Re: Kubernetes backend and docker images

 

+matt +tim

For reference - here's our previous thread on this dockerfile unification problem - https://github.com/apache-spark-on-k8s/spark/pull/60[github.com]

I think this approach should be acceptable from both the customization and visibility perspectives.

 

 

On Mon, Jan 8, 2018 at 9:40 AM, Anirudh Ramanathan <[hidden email]> wrote:

+1

 

We discussed some alternatives early on - including using a single dockerfile and different spec.container.command and spec.container.args from the Kubernetes driver/executor specification (which override entrypoint in docker). No reason that won't work also - except that it reduced the transparency of what was being invoked in the driver/executor/init by hiding it in the actual backend code.  

 

Putting it into a single entrypoint file and branching let's us realize the best of both worlds I think. This is an elegant solution, thanks Marcelo. 

 

On Jan 6, 2018 10:01 AM, "Felix Cheung" <[hidden email]> wrote:

+1

 

Thanks for taking on this.

That was my feedback on one of the long comment thread as well, I think we should have one docker image instead of 3 (also pending in the fork are python and R variant, we should consider having one that we official release instead of 9, for example)

 

 


From: 蒋星博 <[hidden email]>
Sent: Friday, January 5, 2018 10:57:53 PM
To: Marcelo Vanzin
Cc: dev
Subject: Re: Kubernetes backend and docker images

 

Agree it should be nice to have this simplification, and users can still create their custom images by copy/modifying the default one.

Thanks for bring this out Marcelo!

 

2018-01-05 17:06 GMT-08:00 Marcelo Vanzin <[hidden email]>:

Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img[github.com]

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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--

Anirudh Ramanathan


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Re: Kubernetes backend and docker images

Matt Cheah

// Fixing Anirudh's email address


From: Matt Cheah
Sent: Monday, January 8, 2018 1:39:12 PM
To: Anirudh Ramanathan; Felix Cheung
Cc: 蒋星博; Marcelo Vanzin; dev; Timothy Chen
Subject: Re: Kubernetes backend and docker images
 

We would still want images to be able to be uniquely specified for the driver vs. the executors. For example, not all of the libraries required on the driver may be required on the executors, so the user would want to specify a different custom driver image from their custom executor image.

 

But the idea of the entry point script that can switch based on environment variables makes sense.

 

I do think we want separate Python and R images, because Python and R come with non-trivial extra baggage that can make the images a lot bigger and slower to download for Scala-only users.

 

From: Anirudh Ramanathan <[hidden email]>
Date: Monday, January 8, 2018 at 9:48 AM
To: Felix Cheung <[hidden email]>
Cc:
蒋星博 <[hidden email]>, Marcelo Vanzin <[hidden email]>, dev <[hidden email]>, Matt Cheah <[hidden email]>, Timothy Chen <[hidden email]>
Subject: Re: Kubernetes backend and docker images

 

+matt +tim

For reference - here's our previous thread on this dockerfile unification problem - https://github.com/apache-spark-on-k8s/spark/pull/60[github.com]

I think this approach should be acceptable from both the customization and visibility perspectives.

 

 

On Mon, Jan 8, 2018 at 9:40 AM, Anirudh Ramanathan <[hidden email]> wrote:

+1

 

We discussed some alternatives early on - including using a single dockerfile and different spec.container.command and spec.container.args from the Kubernetes driver/executor specification (which override entrypoint in docker). No reason that won't work also - except that it reduced the transparency of what was being invoked in the driver/executor/init by hiding it in the actual backend code.  

 

Putting it into a single entrypoint file and branching let's us realize the best of both worlds I think. This is an elegant solution, thanks Marcelo. 

 

On Jan 6, 2018 10:01 AM, "Felix Cheung" <[hidden email]> wrote:

+1

 

Thanks for taking on this.

That was my feedback on one of the long comment thread as well, I think we should have one docker image instead of 3 (also pending in the fork are python and R variant, we should consider having one that we official release instead of 9, for example)

 

 


From: 蒋星博 <[hidden email]>
Sent: Friday, January 5, 2018 10:57:53 PM
To: Marcelo Vanzin
Cc: dev
Subject: Re: Kubernetes backend and docker images

 

Agree it should be nice to have this simplification, and users can still create their custom images by copy/modifying the default one.

Thanks for bring this out Marcelo!

 

2018-01-05 17:06 GMT-08:00 Marcelo Vanzin <[hidden email]>:

Hey all, especially those working on the k8s stuff.

Currently we have 3 docker images that need to be built and provided
by the user when starting a Spark app: driver, executor, and init
container.

When the initial review went by, I asked why do we need 3, and I was
told that's because they have different entry points. That never
really convinced me, but well, everybody wanted to get things in to
get the ball rolling.

But I still think that's not the best way to go. I did some pretty
simple hacking and got things to work with a single image:

https://github.com/vanzin/spark/commit/k8s-img[github.com]

Is there a reason why that approach would not work? You could still
create separate images for driver and executor if wanted, but there's
no reason I can see why we should need 3 images for the simple case.

Note that the code there can be cleaned up still, and I don't love the
idea of using env variables to propagate arguments to the container,
but that works for now.

--
Marcelo

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--

Anirudh Ramanathan

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Re: Kubernetes backend and docker images

Marcelo Vanzin
In reply to this post by Matt Cheah
On Mon, Jan 8, 2018 at 1:39 PM, Matt Cheah <[hidden email]> wrote:
> We would still want images to be able to be uniquely specified for the
> driver vs. the executors. For example, not all of the libraries required on
> the driver may be required on the executors, so the user would want to
> specify a different custom driver image from their custom executor image.

Are you saying that we should *require* different images for driver
and executor, as is the case today, or that we should *allow*
different images, but default to the same, as I'm proposing?

I see zero reason to require different images. While it's true that
the driver may need more libraries than the executor, 99% of the time
it's ok to just have those libraries everywhere - it makes
configuration easier and doesn't do any harm.


--
Marcelo

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Re: Kubernetes backend and docker images

Matt Cheah
Think we can allow for different images and default to them being the same. Apologize if I missed that as being the original intention though.

-Matt Cheah

On 1/8/18, 1:45 PM, "Marcelo Vanzin" <[hidden email]> wrote:

    On Mon, Jan 8, 2018 at 1:39 PM, Matt Cheah <[hidden email]> wrote:
    > We would still want images to be able to be uniquely specified for the
    > driver vs. the executors. For example, not all of the libraries required on
    > the driver may be required on the executors, so the user would want to
    > specify a different custom driver image from their custom executor image.
   
    Are you saying that we should *require* different images for driver
    and executor, as is the case today, or that we should *allow*
    different images, but default to the same, as I'm proposing?
   
    I see zero reason to require different images. While it's true that
    the driver may need more libraries than the executor, 99% of the time
    it's ok to just have those libraries everywhere - it makes
    configuration easier and doesn't do any harm.
   
   
    --
    Marcelo
   

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