Elastic Container Instance:Mount an emptyDir volume to change the shm size

Use cases

By default, Kubernetes allocates 64 MiB of shared memory to each Pod, which sets the size of the /dev/shm directory to 64 MiB. Kubernetes configurations do not allow you to change this size

To work around this limitation, you can increase the shm size by mounting a memory-type emptyDir volume to /dev/shm.

Configuration example

1. Create a YAML file.

   vim emptydir-shm.yaml

   The following example shows the content of the emptydir-shm.yaml file. This configuration increases the pod's shm size to 256 MiB by mounting a memory-type emptyDir volume with a 256MiB sizeLimit to the /dev/shm directory.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: test
     labels:
       app: test
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         name: nginx-test
         labels:
           app: nginx
           alibabacloud.com/eci: "true" 
       spec:
         containers:
         - name: nginx
           image: registry.cn-shanghai.aliyuncs.com/eci_open/nginx:1.14.2
           ports:
           - containerPort: 80
           volumeMounts:
           - mountPath: /dev/shm
             name: cache-volume
         volumes:
         - emptyDir:
             medium: Memory
             sizeLimit: 256MiB
           name: cache-volume

2. Create the Deployment.

   kubectl create -f emptydir-shm.yaml

3. View the results.

   Log on to the container and run the df -h command to check the disk space. The output confirms that the size of /dev/shm is now 256 MiB.