Node Affinity

Provides us with capabilities to limit pod placement on specific nodes.

 1apiVersion: 
 2kind: Pod
 3metadata:
 4  name: simple-webapp-color
 5spec:
 6  nodeSelector:
 7    size: Large
 8
 9  containers:
10    - name: simple-webapp-color
11      image: simple-webapp-color
12      ports:
13        - containerPort: 8080

 1
 2apiVersion: 
 3kind: Pod
 4metadata:
 5  name: simple-webapp-color
 6spec:
 7  affinity:
 8    nodeAffinity:
 9      requiredDuringSchedulingIgnoredDuringExecution:
10        nodeSelectorTerms:
11          - matchExpressions:
12            - key: size
13              operator: In
14              values:
15                - Large
16                - Medium
17
18
19  containers:
20    - name: simple-webapp-color
21      image: simple-webapp-color
22      ports:
23        - containerPort: 8080

Affinity

 1spec:
 2  affinity:
 3    nodeAffinity:
 4      requiredDuringSchedulingIgnoredDuringExecution:
 5        nodeSelectorTerms:
 6          - matchExpressions:
 7            - key: size
 8              operator: In
 9              values:
10                - Large
11                - Medium
12            - key: environment
13              operator: In
14              values:
15                - test-1
16                - prod-1

Match Expressions

1- matchExpressions:
2    - key: size
3      operator: In
4      values:
5        - Large
6        - Medium
7    
8    - key: color
9      operator: Exists

Node Affinity

requiredDuringSchedulingIgnoredDuringExecution

prefferedDuringSchedulingIgnoredDuringExecution

requiredDuringSchedulingRequiredDuringExecution

required - If label not found, do not schedule

Preffered - If label not found, place anywhere

Ignored - Any changes in node affinity will not affect them

During SchedulingDuring Execution
Type 1RequiredIgnored
Type 2PrefferedIgnored
Type 3RequiredRequired

If post deplyment a label changes, RequiredDuringExecution will kill any existing pods that do not match the labels