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K.I.S.S Kubernetes deployment script

Sep 5 2019

Following this simple process, you can create configurable Kubernetes deployment definitions, without having to learn and use a tool like Helm:

  1. Create a set of Kubernetes yaml resource files in your working directory, setting environment variables you’d like to replace: $FOO or ${BAR}
  2. Export the environment variables - the environment variable substitution using envsubst will fail if there are environment variables that aren’t set.
  3. Run the bash script, passing your working directory as the first argument deploy.sh .
  4. This will generate a directory called deployments/ with a timestamped directory containing the generated Kubernetes resource files. kubectl apply -f --dry-run ... is run with the --dry-run option to check that the resource definitions are valid.
  5. When you’re happy and ready to apply the resource updates, run the same command without the dry-run option: kubectl apply -f deployments/deploy_{date} 
#!/bin/sh -ex

OUTPUT_DIR=$1/deployments/deploy_$(date +%F-%T)
mkdir -p $OUTPUT_DIR

for FILE in $1/*.yaml
do
  echo "Creating deployment"
  envsubst <$FILE> $OUTPUT_DIR/$FILE
done

kubectl apply -f $OUTPUT_DIR --dry-run -o yaml > $OUTPUT_DIR/output.yaml
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