Kubernetes 101 : Generating Yaml files for Kubernetes objects and environment variables
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:
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.
Remark:
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:
- MONGO_INITDB_ROOT_USERNAME
- MONGO_INITDB_ROOT_PASSWORD
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