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I need to start kubernetes pods in a sequence like pod2 should start only when pod1 is up and running.
we can do this in docker-compose.yml using depends_on
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depends_on is a Docker Compose keyword to set the order in which services must start and stop. For example, suppose we want our web application, which we'll build as a web-app image, to start after our Postgres container.
To create a Kubernetes pod with YAML, you first create an empty file, assign it the necessary access permissions, and then define the necessary key-value pairs. The important ones are the apiVersion, the kind (pod), name, and the containers within the pod.
To create a pod using the nginx image, run the command kubectl run nginx --image=nginx --restart=Never . This will create a pod named nginx, running with the nginx image on Docker Hub. And by setting the flag --restart=Never we tell Kubernetes to create a single pod rather than a Deployment.
Yes, you can add multiple container with same image. The containers object must contain: name: Name of the container. It must be a DNS_LABEL and be unique within the pod.
No, there is no built-in dependency management equivalent to depends_on available. In general, we assume loosely coupled services and as a good practice there should be no hard dependency in terms of start-up order, but retries and timeouts should be used. If you have to hardcode dependencies, you can use init containers. In your case, a init container in pod2 could simply query if pod1 (or better: the service in front of it) is ready in a while loop. The main container in pod2 is guaranteed only to be launched if and when the init container exits successfully.
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There isn't a direct equivalent to dependency with Kubernetes primitives, as a workaround you can implement a readiness probe that will render pod2 unusable until it sees pod1 up and running.
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