Add vault-login script for user authentication

bin/vault-login

@@ -0,0 +1,17 @@
+# Check, if we are sourced, that's a requirement for this script
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+  echo "This script must be sourced, not executed directly."
+  echo "Use: source bin/vault-login"
+  exit 1
+fi
+
+# v_login function may be added to .bashrc, .zprofile, etc.
+function v_login() {
+    local VAULT_USERNAME=${1:-adminslawek}
+    vault login -format=json -method=userpass username="$VAULT_USERNAME" |
+        jq -r '.auth | [.client_token, .accessor] | @tsv' | read -r VAULT_TOKEN TOKEN_ACCESSOR
+    echo "Logged in as $VAULT_USERNAME (Token accessor: $TOKEN_ACCESSOR)"
+    export VAULT_TOKEN TOKEN_ACCESSOR
+}
+
+v_login "$@"