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79bf74e Oct 24, 2018
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Downloading binaries and containers

Kubespray supports several download/upload modes. The default is:

  • Each node downloads binaries and container images on its own, which is download_run_once: False.
  • For K8s apps, pull policy is k8s_image_pull_policy: IfNotPresent.
  • For system managed containers, like kubelet or etcd, pull policy is download_always_pull: False, which is pull if only the wanted repo and tag/sha256 digest differs from that the host has.

There is also a "pull once, push many" mode as well:

  • Override the download_run_once: True to download container images only once then push to cluster nodes in batches. The default delegate node for pushing images is the first kube-master.
  • If your ansible runner node (aka the admin node) have password-less sudo and docker enabled, you may want to define the download_localhost: True, which makes that node a delegate for pushing images while running the deployment with ansible. This maybe the case if cluster nodes cannot access each over via ssh or you want to use local docker images as a cache for multiple clusters.

Container images and binary files are described by the vars like foo_version, foo_download_url, foo_checksum for binaries and foo_image_repo, foo_image_tag or optional foo_digest_checksum for containers.

Container images may be defined by its repo and tag, for example: andyshinn/dnsmasq:2.72. Or by repo and tag and sha256 digest: andyshinn/dnsmasq@sha256:7c883354f6ea9876d176fe1d30132515478b2859d6fc0cbf9223ffdc09168193.

Note, the sha256 digest and the image tag must be both specified and correspond to each other. The given example above is represented by the following vars:

dnsmasq_digest_checksum: 7c883354f6ea9876d176fe1d30132515478b2859d6fc0cbf9223ffdc09168193
dnsmasq_image_repo: andyshinn/dnsmasq
dnsmasq_image_tag: '2.72'

The full list of available vars may be found in the download's ansible role defaults. Those also allow to specify custom urls and local repositories for binaries and container images as well. See also the DNS stack docs for the related intranet configuration, so the hosts can resolve those urls and repos.

Offline environment

In case your servers don't have access to internet (for example when deploying on premises with security constraints), you'll have, first, to setup the appropriate proxies/caches/mirrors and/or internal repositories and registries and, then, adapt the following variables to fit your environment before deploying:

  • At least foo_image_repo and foo_download_url as described before (i.e. in case of use of proxies to registries and binaries repositories, checksums and versions do not necessarily need to be changed). NB: Regarding foo_image_repo, when using insecure registries/proxies, you will certainly have to append them to the docker_insecure_registries variable in group_vars/all/docker.yml
  • pyrepo_index (and optionally pyrepo_cert)
  • Depending on the container_manager
    • When container_manager=docker, docker_foo_repo_base_url, docker_foo_repo_gpgkey, dockerproject_bar_repo_base_url and dockerproject_bar_repo_gpgkey (where foo is the distribution and bar is system package manager)
    • When container_manager=crio, crio_rhel_repo_base_url
  • When using Helm, helm_stable_repo_url