#!/usr/bin/env bash
# Config trees: what a Kubernetes ConfigMap or Secret actually looks like to Spring Boot.
#
# A ConfigMap mounted as a volume is not a properties file. Kubernetes writes one file per
# key, named after the key, containing only the value. `configtree:` is the loader that reads
# that shape. This script builds the same directory layout on disk, so the demonstration is
# the real mechanism rather than a description of it.
set -euo pipefail
set +m
cd "$(dirname "$0")/.."
source scripts/env.sh

TREE="${TMPDIR:-/tmp}/demo-configmap"
SECRET="${TMPDIR:-/tmp}/demo-secret"
rm -rf "$TREE" "$SECRET"; mkdir -p "$TREE" "$SECRET"

# Exactly what `kubectl create configmap demo --from-literal=demo.greeting=...` produces
# once mounted: one file per key, the filename IS the property name.
printf 'from-configmap-volume'                 > "$TREE/demo.greeting"
printf 'jdbc:postgresql://configmap-db:5432/o' > "$TREE/demo.datasource-url"
printf '25'                                    > "$TREE/demo.pool-size"
# Nested keys use a directory per level, or a dotted filename. Both work.
mkdir -p "$TREE/demo/nested"
printf 'from-nested-directory'                 > "$TREE/demo/nested/value"
# A Secret mount looks identical; only the permissions differ.
printf 'sk_live_not_a_real_key'                > "$SECRET/demo.api-key"

{
  echo "== what Kubernetes actually mounts =="
  echo "\$ find $TREE $SECRET -type f | sort"
  find "$TREE" "$SECRET" -type f | sort | sed "s|$TREE|<configmap-mount>|;s|$SECRET|<secret-mount>|"
  echo
  echo "\$ cat <configmap-mount>/demo.greeting; echo"
  cat "$TREE/demo.greeting"; echo
  echo
  echo "Each file holds a bare value with no trailing newline and no key. There is no"
  echo "properties syntax to parse -- the filename is the key."
  echo
  echo "== importing it =="
  echo "\$ java -jar $JAR \\"
  echo "    --spring.config.import=configtree:$TREE/,configtree:$SECRET/"
  echo
  start_app "--spring.config.import=configtree:$TREE/,configtree:$SECRET/" > /dev/null
  report demo.greeting
  echo
  echo "  demo.pool-size      = $(curl -s "http://127.0.0.1:${APP_PORT}/precedence?name=demo.pool-size" | python3 -c 'import json,sys; print(json.load(sys.stdin)["effectiveValue"])')"
  echo "  demo.nested.value   = $(curl -s "http://127.0.0.1:${APP_PORT}/precedence?name=demo.nested.value" | python3 -c 'import json,sys; print(json.load(sys.stdin)["effectiveValue"])')"
  echo "  demo.api-key        = $(curl -s "http://127.0.0.1:${APP_PORT}/precedence?name=demo.api-key" | python3 -c 'import json,sys; print(json.load(sys.stdin)["effectiveValue"])')"
  echo
  echo "A directory under the mount becomes a nested property: demo/nested/value is"
  echo "demo.nested.value. That is how a ConfigMap with slashes in its keys arrives."
  echo
  echo "== the part that surprises people =="
  echo "An imported config tree outranks application.yaml, but it is still config data,"
  echo "so it still loses to an environment variable:"
  echo
  APP_ENV="DEMO_GREETING=from-environment-variable" \
    start_app "--spring.config.import=configtree:$TREE/" > /dev/null
  report demo.greeting
  echo
  echo "There is also no such thing as a profile-specific config tree. There is no"
  echo "<mount>-prod directory convention; a per-environment ConfigMap is a different mount"
  echo "chosen by the deployment, not by spring.profiles.active."
  stop_app
} > docs/output/03-config-tree.txt 2>&1
cat docs/output/03-config-tree.txt