Configure the NTP service for containers - Elastic Container Instance

In time-sensitive applications, unsynchronized container clocks can lead to issues such as data inconsistencies in distributed systems or misleading timestamps in logs. To prevent these problems, you can configure the Network Time Protocol (NTP) service for your Elastic Container Instance pods. This ensures accurate time synchronization within your containers, maintaining data integrity and reliable application behavior.

Configuration description

When you create an Elastic Container Instance pod, you can add the k8s.aliyun.com/eci-ntp-server annotation to the pod to specify the address of the NTP server. This ensures that the containers within the pod synchronize their time with the specified NTP server, maintaining time accuracy.

Important

Annotations must be added to the metadata in the configuration file of the pod. For example, when you create a Deployment, you must add annotations in the spec.template.metadata section.
Elastic Container Instance-related annotations are only applied when a pod is created. Adding or modifying these annotations on an existing pod will have no effect.

Configuration example

Create an application with the NTP service configuration.

kubectl create -f set-ntp.yaml

The following code provides the content of a sample set-ntp.yaml file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: test-ntp
  labels:
    app: test
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      name: test-ntp
      labels:
        app: nginx
        alibabacloud.com/eci: "true" 
      annotations:
        k8s.aliyun.com/eci-ntp-server: 100.100.XX.XX  # Specifies the IP address of the NTP server.
    spec:
      containers:
      - name: nginx
        image: registry.cn-shanghai.aliyuncs.com/eci_open/centos:7
        ports:
        - containerPort: 80
        command: ["/bin/sh","-c","sleep 3600" ]

Log on to the container and verify the NTP configuration.

Query the information about the pod.

kubectl get pod

The following command output is returned:

NAME                        READY   STATUS    RESTARTS   AGE
test-ntp-599d5ff9f5-9kb56   1/1     Running   0          3m59s

Access the container.

kubectl exec -it test-ntp-599d5ff9f5-9kb56 -- bash

Check the container's time synchronization source.

chronyc sources

Note

If chrony is not installed, you can run the yum -y install chrony command to install chrony.

The command output should list the IP address of your NTP server, which confirms that the service is configured correctly. The following is a sample output.

210 Number of sources = 1
MS Name/IP address         Stratum Poll Reach LastRx Last                            sample
===============================================================================
^* 100.100.XX.XX                    2           6     377     35       +40us[ +135us] +/-   14ms