container.training/slides/k8s/shippingimages.md

Shipping images with a registry

• Initially, our app was running on a single node

• We could build and run in the same place

• Therefore, we did not need to ship anything

• Now that we want to run on a cluster, things are different

• The easiest way to ship container images is to use a registry

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How Docker registries work (a reminder)

• What happens when we execute docker run alpine ?

• If the Engine needs to pull the alpine image, it expands it into library/alpine

• library/alpine is expanded into index.docker.io/library/alpine

• The Engine communicates with index.docker.io to retrieve library/alpine:latest

• To use something else than index.docker.io, we specify it in the image name

• Examples:

  docker pull gcr.io/google-containers/alpine-with-bash:1.0
  
  docker build -t registry.mycompany.io:5000/myimage:awesome .
  docker push registry.mycompany.io:5000/myimage:awesome
  

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Running DockerCoins on Kubernetes

• Create one deployment for each component

  (hasher, redis, rng, webui, worker)

• Expose deployments that need to accept connections

  (hasher, redis, rng, webui)

• For redis, we can use the official redis image

• For the 4 others, we need to build images and push them to some registry

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Building and shipping images

• There are many options!

• Manually:

  • build locally (with docker build or otherwise)

  • push to the registry

• Automatically:

  • build and test locally

  • when ready, commit and push a code repository

  • the code repository notifies an automated build system

  • that system gets the code, builds it, pushes the image to the registry

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Which registry do we want to use?

• There are SAAS products like Docker Hub, Quay ...

• Each major cloud provider has an option as well

  (ACR on Azure, ECR on AWS, GCR on Google Cloud...)

• There are also commercial products to run our own registry

  (Docker EE, Quay...)

• And open source options, too!

• When picking a registry, pay attention to its build system

  (when it has one)

---

Building on the fly

• Conceptually, it is possible to build images on the fly from a repository

• Example: ctr.run

  (deprecated in August 2020, after being aquired by Datadog)

• It did allow something like this:

  docker run ctr.run/github.com/jpetazzo/container.training/dockercoins/hasher
  

• No alternative yet

  (free startup idea, anyone?)

???

:EN:- Shipping images to Kubernetes :FR:- Déployer des images sur notre cluster