read grafana's datasource key from the store into /run, seeding an empty store from the old file

nix/script-tests/grafana-secret-key.sh

@@ -0,0 +1,89 @@
+# Cases for ./grafana-secret-key.nix. Each case sets up the store's leaf, the
+# seed file and the stub's behaviour, runs `grafana_secret_key` the way the
+# unit's script does, and compares its status, the key it hands over and what
+# the store holds afterwards.
+set -uo pipefail
+
+failures=0
+leaf=secret/swarm/services/t/secret-key
+
+# setup <description>
+setup() {
+  case=$1
+  dir=$(mktemp -d)
+  mkdir "$dir/kv"
+  export FAKE_BAO_KV=$dir/kv FAKE_BAO_LOG=$dir/bao.log FAKE_BAO_LOGIN_RC=0
+  unset FAKE_BAO_DENY_READ FAKE_BAO_DENY_WRITE FAKE_BAO_RACE
+  : >"$FAKE_BAO_LOG"
+  seed=$dir/secret_key
+  stored=$FAKE_BAO_KV/$(printf '%s' "$leaf" | tr / _)
+}
+
+mint() {
+  printf 'minted-key\n'
+}
+
+# expect <status> <key> <what the store holds, "" for nothing>
+expect() {
+  (
+    PATH="$FAKE_BAO_BIN:$PATH"
+    unset BAO_TOKEN
+    # shellcheck source=/dev/null
+    . "$HELPER"
+    rc=0
+    grafana_secret_key "$leaf" "$seed" mint >/dev/null 2>"$dir/err" || rc=$?
+    printf '%s' "$rc" >"$dir/rc"
+    printf '%s' "$GRAFANA_KEY" >"$dir/key"
+  )
+  held=$(cat "$stored" 2>/dev/null)
+  if [ "$(cat "$dir/rc")" != "$1" ]; then fail "exited $(cat "$dir/rc"), wanted $1: $(cat "$dir/err")"; fi
+  if [ "$(cat "$dir/key")" != "$2" ]; then fail "handed over '$(cat "$dir/key")', wanted '$2'"; fi
+  if [ "$held" != "$3" ]; then fail "the store holds '$held', wanted '$3'"; fi
+}
+
+fail() {
+  echo "FAILED: $case: $*" >&2
+  failures=$((failures + 1))
+}
+
+setup "an empty store takes the seed's key"
+printf 'seed-key\n' >"$seed"
+expect 0 seed-key seed-key
+grep -q '^kv put -cas=0 ' "$FAKE_BAO_LOG" || fail "no create-only write"
+[ -e "$seed" ] || fail "the seed file was removed"
+
+setup "a store that holds a key wins over the seed, and is not written"
+printf 'seed-key\n' >"$seed"
+printf 'store-key' >"$stored"
+expect 0 store-key store-key
+! grep -q '^kv put' "$FAKE_BAO_LOG" || fail "wrote to the store"
+
+setup "with no seed and an empty store, a key is minted and stored"
+expect 0 minted-key minted-key
+
+setup "a store that refuses the login mints nothing, with or without a seed"
+export FAKE_BAO_LOGIN_RC=1
+expect 1 "" ""
+printf 'seed-key\n' >"$seed"
+expect 1 "" ""
+
+setup "a store that refuses the read stores and hands over nothing"
+printf 'seed-key\n' >"$seed"
+export FAKE_BAO_DENY_READ=1
+expect 1 "" seed-key
+
+setup "a store that refuses the write hands over nothing"
+export FAKE_BAO_DENY_WRITE=1
+expect 1 "" ""
+
+setup "a store that holds an empty value hands over nothing"
+: >"$stored"
+expect 1 "" ""
+
+setup "a lost race takes the winner's key"
+printf 'seed-key\n' >"$seed"
+export FAKE_BAO_RACE=other-key
+expect 0 other-key other-key
+
+echo "$failures failures"
+[ "$failures" = 0 ]