Simple script useful to inspect exiting claims on Kubernetes

inspect-claims.sh

#!/usr/bin/env bash

set -o errexit
set -o nounset
set -o pipefail

# Constants
RESET='\033[0m'
GREEN='\033[38;5;2m'
RED='\033[38;5;1m'
YELLOW='\033[38;5;3m'

# Axiliar functions
########################
# Log message to stderr
# Arguments:
#   $1 - Message to log
#########################
log() {
  printf "%b\n" "${*}" >&2
}
########################
# Log info message
# Arguments:
#   $1 - Message to log
#########################
info() {
    log "${GREEN}INFO ${RESET} ==> ${*}"
}
########################
# Log error message
# Arguments:
#   $1 - Message to log
#########################
error() {
    log "${RED}ERROR ${RESET} ==> ${*}"
}
########################
# Print menu
#########################
print_menu() {
    local script
    script=$(basename "${BASH_SOURCE[0]}")
    log "${RED}NAME${RESET}"
    log "    $(basename -s .sh "${BASH_SOURCE[0]}")"
    log ""
    log "${RED}SYNOPSIS${RESET}"
    log "    $script [${YELLOW}-dh${RESET}] [${YELLOW}-n ${GREEN}\"namespace\"${RESET}] [${YELLOW}-c ${GREEN}\"claim-name\"${RESET}]"
    log ""
    log "${RED}DESCRIPTION${RESET}"
    log "    Script to create a single-container POD on your K8s cluster to inspect existing PVCs."
    log ""
    log "    The options are as follow:"
    log ""
    log "      ${YELLOW}-n, --namespace ${GREEN}[namespace]${RESET}           Namespace where te create the POD."
    log "      ${YELLOW}-c, --claim${RESET}                           Name of the existing PVC to inspect (can be set several times)."
    log "      ${YELLOW}-h, --help${RESET}                            Print this help menu."
    log "      ${YELLOW}-u, --dry-run${RESET}                         Enable \"dry run\" mode."
    log ""
    log "${RED}EXAMPLES${RESET}"
    log "      $script --help"
    log "      $script --namespace \"default\" --claim \"claim-0\""
    log ""
}

namespace="default"
claims=()
help_menu=0
dry_run=0
while [[ "$#" -gt 0 ]]; do
    case "$1" in
        -h|--help)
            help_menu=1
            ;;
        -u|--dry-run)
            dry_run=1
            ;;
        -n|--namespace)
            shift; namespace="${1:?missing namespace}"
            ;;
        -c|--claim)
            shift; claims+=("${1:?missing claim}")
            ;;
        *)
            error "Invalid command line flag $1" >&2
            exit 1
            ;;
    esac
    shift
done

if [[ ${#claims[@]} -eq 0 ]]; then
    help_menu=1
    error "No PVC(s) were indicated"
fi
if [[ "$help_menu" -eq 1 ]] ; then
    print_menu
    exit 0
fi
used_pvcs() {
    kubectl get pods -n "$namespace" -o json | jq -c '.items[] | {claimName: .spec |  select( has ("volumes") ).volumes[] | select( has ("persistentVolumeClaim") ).persistentVolumeClaim.claimName }' | sort -u
}
for c in "${claims[@]}"; do
    if ! kubectl get pvc -n "$namespace" "$c" >/dev/null 2>&1; then
        error "PVC $c not found"
        exit 1
    fi
    if [[ "$(kubectl get pvc -n "$namespace" "$c" -o json | jq '.status.accessModes[]')" = *"ReadWriteOnce"* ]] && [[ "$(used_pvcs)" = *"$c"* ]]; then
        error "PVC $c has ReadWriteOnce access mode and it's already in use"
        exit 1
    fi
done

pod_template="(mktemp)"
cleanup() {
    rm "$pod_template"
}
trap cleanup EXIT
cat > "$pod_template" << EOF
apiVersion: v1
kind: Pod
metadata:
  name: claim-inspector
  namespace: $namespace
spec:
  restartPolicy: Never
  containers:
  - image: docker.io/bitnami/bitnami-shell:latest
    name: inspector
    command:
    - sleep
    - infinity
    volumeMounts:
EOF
for c in "${claims[@]}"; do
    cat >> "$pod_template" << EOF
    - mountPath: /vol/${c}
      name: pv-${c}
EOF
done
cat >> "$pod_template" << EOF
  volumes:
EOF
for c in "${claims[@]}"; do
  cat >> "$pod_template" << EOF
  - name: pv-${c}
    persistentVolumeClaim:
      claimName: ${c}
EOF
done

if [[ "$dry_run" -eq 1 ]]; then
    info "DRY RUN mode enabled!"
    info "Namespace: $namespace"
    info "Generated POD manifest:"
    cat "$pod_template"
    exit 0
fi

info "Creating inspector POD"
if kubectl get pods -n "$namespace" claim-inspector >/dev/null 2>&1; then
    error "There's an claim inspector POD already running"
    exit 1
fi
if ! kubectl create -f "$pod_template" >/dev/null 2>&1; then
    error "POD creating failed"
    exit 1
fi
info "POD successfully created!"
info "Use the command below to access the container:"
log ""
log "    kubectl exec -n $namespace -it claim-inspector -c inspector -- bash"
log ""
info "Then, inspect the data in the volumes mounted at \"/vol\":"
log ""
log "    ls -la /vol"
log ""
info "Remember to delete the POD by running the command below once it's no needed anymore:"
log ""
log "    kubectl delete pod -n $namespace claim-inspector"