Create base-image and minimize layer count #324
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johscheuer
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Thanks for contributing this - I see no problems and think we can afford to put this in the next release. What do you think @ash211 ? |
| ENV SPARK_HOME /opt/spark | ||
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| WORKDIR /opt/spark | ||
| COPY examples /opt/spark/examples |
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What's the difference between ADD and COPY?
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Looks like ADD supports URLs and extracting files out of tarballs which COPY does not
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Good summary of ADD vs COPY : https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/#add-or-copy
ADD is somewhat deprecated because it has complex behaviors. Recommended best practice is to copy tar-balls and unpack them explicitly in a RUN
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The support for unpacking tarballs is actually one of the side-effects of ADD that is considered harder to reason about. I think the idea is, just looking at a docker-file you may not be able to tell exactly what operations that ADD is doing. I don't have a real strong opinion on that. It's arguably more convenient too. But that's the current "official" position.
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Like @erikerlandson said, I would prefer to use COPY since the files only copied into the image (and no magic is needed).
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| # limitations under the License. | |||
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| FROM openjdk:8-alpine | |||
| FROM spark-base | |||
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Should this have a tag, i.e. latest? How do we ensure that the child images are kept in sync with the right tag of the base?
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imo there should be a tag per spark release, something like spark-base:2.1.0, etc
I'd propose renaming it spark-kubernetes-base
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How would we handle snapshots then? Or are we only going to push images on every release, at which point we update all of the Dockerfiles?
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ideally these would have version tags like 2.1.0-kubernetes-0.3.0 rather than something like latest (I'm a fan of immutable artifacts)
We'd need to have some way of templating Dockerfiles to do that though I think
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I'm not familiar with how people treat hadoop versions, but if we need multiple hadoop versions as part of the build crossproduct, then that would also be a part of the tag
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I think what we need is some string replacement in the release process e.q. when version 2.1 is released a placeholder in the files (like RELEASE) get's replaced by the actual value.
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as long as we build in the correct order (spark-base first) I think we're fine.
@erikerlandson do you feel strongly about renaming this to spark-kubernetes-base? The others are just driver executor etc
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My instinct is that it would be preferable to name them all spark-kubernetes-*, but I don't consider it a show stopper
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I think we want spark-kubernetes because we might namespace conflict with Nomad in particular, which is another effort being done to run the driver and executors in Docker containers.
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Actually the image tagging question stands as something that might make us want to reconsider this approach. |
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@johscheuer I'm not sure what Can you explain more what It seems most of the benefits are in squashing the |
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In using a base image we can avoid duplicating the Dockerfile code itself. |
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So for example when we start supporting Python we only have to include the Python installation in one Dockerfile and not two. |
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The main idea is like @mccheah said to avoid duplicating Dockerfile code. Assume we need to adjust a library or we want to include another one in all images then we would need to modify all images. If you want I can separate these changes into two PR's -> one for the merge of the |
| docker build -t registry-host:5000/spark-driver:latest -f dockerfiles/driver/Dockerfile . | ||
| docker build -t registry-host:5000/spark-executor:latest -f dockerfiles/executor/Dockerfile . | ||
| docker build -t registry-host:5000/spark-init:latest -f dockerfiles/init-container/Dockerfile . | ||
| docker push registry-host:5000/spark-base:latest | ||
| docker push registry-host:5000/spark-driver:latest | ||
| docker push registry-host:5000/spark-executor:latest | ||
| docker push registry-host:5000/spark-init:latest |
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I think we need a note after this that the build order matters -- the spark-base must be built first, then the others can be built afterwards in any order
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| # limitations under the License. | |||
| # | |||
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| FROM openjdk:8-alpine | |||
| FROM spark-base | |||
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as long as we build in the correct order (spark-base first) I think we're fine.
@erikerlandson do you feel strongly about renaming this to spark-kubernetes-base? The others are just driver executor etc
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LGTM pending question for Erik (and updating the branch) |
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Thanks @johscheuer ! |
* Create base-image and minimize layer count * Create running-on-kubernetes.md
…-kubernetes Rebase to upstream's version of Kubernetes support.
* Create base-image and minimize layer count * Create running-on-kubernetes.md
What changes were proposed in this pull request?
Use one single layer for the run command and tool installation. Also move all the common parts into one base-image.
Fixes #323
How was this patch tested?
Tested with the Minikube integration test (https://github.com/apache-spark-on-k8s/spark/blob/branch-2.1-kubernetes/resource-managers/kubernetes/README.md#preserve-the-minikube-vm)
cc @ash211