Fail loudly if jsonnet isn't on path

Author: consideRatio

deploy.py

@@ -209,6 +209,13 @@ def main():
     if not grafana_token:
         raise ValueError("The environment variable GRAFANA_TOKEN needs to be set in order to deploying dashboards to a Grafana deployment.")
 
+    # ensure jsonnet (go-jsonnet)
+    if not shutil.which("jsonnet"):
+        raise ValueError(
+            "No jsonnet binary was found on path! "
+            "Install go-jsonnet via https://github.com/google/go-jsonnet/releases."
+        )
+
     api = partial(
         grafana_request,
         args.grafana_url,