I want to apt-get install sysstat command in kubernetes yaml file

The best practice is to install packages at image build stage. You can simply add this step to your Dockerfile.

FROM postgres:9.6RUN apt-get update &&\     apt-get install sysstat -y &&\    rm -rf /var/lib/apt/lists/*COPY deploy/db/init_ddl.sh /docker-entrypoint-initdb.d/RUN chmod +x /docker-entrypoint-initdb.d/init_ddl.sh

Kube Manifest

   spec:      containers:       - name: postgres         image: harik8/sof:62298191         imagePullPolicy: Always         ports:          - containerPort: 5432         env:         - name: POSTGRES_PASSWORD           value: password         volumeMounts:         - name: pvc-db-volume           mountPath: /var/lib/postgresql

It should run (Please ignore POSTGRES_PASSWORD env variable)

$ kubectl get poNAME                    READY   STATUS      RESTARTS   AGEsbdemo-postgres-sfs-0   1/1     Running     0          8m46s

Validation

$ kubectl exec -it sbdemo-postgres-sfs-0 bashroot@sbdemo-postgres-sfs-0:/# iostatLinux 4.19.107 (sbdemo-postgres-sfs-0)  06/10/2020      _x86_64_        (4 CPU)avg-cpu:  %user   %nice %system %iowait  %steal   %idle          10.38    0.01    6.28    0.24    0.00   83.09Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtnvda             115.53      1144.72      1320.48    1837135    2119208scd0              0.02         0.65         0.00       1048          0

If this is possible, something is wrong. Your container should not be running as root and so even if you fixed this approach, it shouldn’t work. What you need to do is put this in your container build instead (I.e. in the Dockerfile).