WEBVTT

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Hello and welcome to this lecture.

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Now that we have learned
about taints and tolerations,

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and node affinity,

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let us tie together the two concepts
through a fun exercise.

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We have three nodes and three pods
each in three colors,

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blue, red and green.

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The ultimate aim is to place
the blue pod in the blue node,

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the red pod in the red node
and likewise for green.

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We are sharing
the same Kubernetes cluster

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with other teams.

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There are other pods in the cluster
as well as other nodes.

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We do not want any other pod
to be placed on our node.

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Neither do we want our pods
to be placed on their nodes.

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Let us first
try to solve this problem

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using taints and tolerations.

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We apply a taint to the nodes,
marking them with their colors,

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blue, red, and green.

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We then set a toleration on the pods
to tolerate the respective colors.

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When the pods are now created,

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the nodes ensure

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they only accept the pods
with the right toleration.

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The green pod ends up
on the green node,

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and the blue pod ends up
on the blue node.

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However,

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taints and tolerations
does not guarantee

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that the pods
will only prefer these nodes,

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so the red node ends up
on one of the other nodes

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that do not have
a taint or toleration set.

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This is not desired.

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Let us try to solve the same problem
with node affinity.

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With node affinity,

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we first label the nodes
with their respective colors,

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blue, red and green.

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We then set
node selectors on the pods

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to tie the pods to the nodes.

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As such,
the pods end up on the right nodes.

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However, that does not guarantee

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that other pods
are not placed on these nodes.

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In this case,

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there is a chance

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that one of the other pods
may end up on our nodes.

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This is not something we desire.

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As such,

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a combination
of taints and tolerations

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and node affinity rules

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can be used together

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to completely dedicate nodes
for specific parts.

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We first use taints and tolerations

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to prevent other pods
from being placed on our nodes.

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Then we use node affinity

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to prevent our pods
from being placed on their nodes.

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Well, that's it for this lecture.

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Head over to the coding exercises

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and play around
with taints, tolerations

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and node affinity.