Starts local Kubernetes API proxy and creates a suitable context, runs application, then stops the proxy after the application has finished.

runwithkp.sh

#!/bin/bash

CONTEXT="minikube"
PROXYCONTEXT="proxykube"

function cleanup {
    kubectl config delete-context $PROXYCONTEXT 2>/dev/null
    kubectl config delete-cluster $PROXYCONTEXT 2>/dev/null
}

# Start the host-local proxy to a Kubernetes remote API in the background and
# then parse its stdout output. As we later want to shut down the proxy again,
# we need its PID. But we only get the correct PID if we make the newly
# started subshell to replace itself with the kubectl process, instead of
# kubectl running as a child process inside the subshell. Thus, we need to
# "exec" kubectl inside the subshell.
#
# See also: https://ubuntuforums.org/showthread.php?t=979694
echo "starting API proxy for context:" "$CONTEXT"
exec 3< <(exec kubectl --context "$CONTEXT" proxy --port 0)
PROXYPID=$!
echo "API proxy PID:" $PROXYPID

# Wait for the proxy to report back the TCP port it has dynamically
# allocated...
PORT=
while read -r line; do
    case "$line" in
    "Starting to serve on "*)
        PORT=$(echo "$line" | sed -r "s/^.*:([0-9]+)/\1/")
        break
        ;;
    *)
        echo "kubectl problem:" "$line"
        ;;
    esac
done <&3

# Has kubectl already terminated, closing its stdout? Then we never got a
# suitable port number...
if [ -z "$PORT" ]; then
    echo "error: kubectl proxy failed"
    exit 1
fi

echo "host-local Kubernetes API proxy at port:" $PORT

# Create a temporary context for, erm, unauthorized access via the proxy.
cleanup
kubectl config set-cluster $PROXYCONTEXT --server=http://127.0.0.1:$PORT
kubectl config set-credentials $PROXYCONTEXT
kubectl config set-context $PROXYCONTEXT --cluster=$PROXYCONTEXT --user=$PROXYCONTEXT

# Drain the proxy's stdout in the background as it has the need to talk to
# us...
coproc proxystdout {
    while read -r line; do
        echo "kubectl proxy:" "$line"
    done
}

STOP=
function stop {
    STOP="stop"
    echo
}
trap stop SIGINT
for x in 1 2 3 4 5 6; do
    if [ ! -z "$STOP" ]; then break; fi
    echo -n "."
    sleep 10
done
echo
trap - SIGINT

# Finally shut down the proxy again, after our test application has run to
# (in)completion.
echo "stopping API proxy PID $PID..."
kill $PROXYPID
cleanup