Kubernetes 101 : Generating Yaml files for Kubernetes objects and environment variables
A ready to use Yaml file:
To create a Yaml file describing a pod for example without creating the pod object, we use the below command:
--dry-run: this option instructs kubernetes to create the Yaml file that represents the pod without creating the pod itself.
The resulting Yaml file is saved in "deploy-1.yaml".
We can then change the file to suit our needs, then we run the below command to create the kubernetes object (pod):
Usually a pod "hosts" one container as shown in the Yaml file below:
But it could also "host" more than one container as we can see in the example below (debian and ubuntu):
Environment variables are one way we could use to pass information to containers when they start running.
Below is an example of an environment variable:
We can see that the "debian" container has access to the "sleep-time" variable. It can use it, for example as an argument to a specific program.
Environment variables are set at the container level as we can see above.
We can check the environment variable of different images by looking at the specifications of each image in their registry - docker hub for example -.
For the "mongoDB" image, we can find the following environment variables that we could pass to a "mongoDB" pod for example: