A security context defines the operating system security settings (uid, gid, capabilities, SELinux role, etc..) applied to a container. See security context design for more details.
There are two levels of security context: pod level security context, and container level security context.
Setting security context at the pod applies those settings to all containers in the pod
apiVersion: v1 kind: Pod metadata: name: hello-world spec: containers: # specification of the pod’s containers # ... securityContext: fsGroup: 1234 supplementalGroups:  seLinuxOptions: level: "s0:c123,c456"
Please refer to the API documentation for a detailed listing and description of all the fields available within the pod security context.
Another functionality of pod level security context is that it applies
those settings to volumes where applicable. Specifically
seLinuxOptions are applied to the volume as follows:
Volumes which support ownership management are modified to be owned
and writable by the GID specified in
fsGroup. See the
Ownership Management design document
for more details.
Volumes which support SELinux labeling are relabled to be accessable
by the label specified unders
seLinuxOptions. Usually you will only
need to set the
level section. This sets the SELinux MCS label given
to all containers within the pod as well as the volume.
Attention: Once the MCS label is specified in the pod description all pods with the same label will able to access the volume. So if interpod protection is needed you must ensure each pod is assigned a unique MCS label.
Container level security context settings are applied to the specific container and override settings made at the pod level where there is overlap. Container level settings however do not affect the pod’s volumes.
apiVersion: v1 kind: Pod metadata: name: hello-world spec: containers: - name: hello-world-container # The container definition # ... securityContext: privileged: true seLinuxOptions: level: "s0:c123,c456"
Please refer to the API documentation for a detailed listing and description of all the fields available within the container security context.