python protobuf validation

protobuf/python/README.md

@@ -0,0 +1,50 @@
+
+## Usage
+
+```shell
+python3 -m venv .venv
+source .venv/bin/activate
+pip install -r requirements.txt
+protoc -I=schema --python_out=. schema/sdk.proto
+python validate.py
+```
+
+## Observations
+
+- Maps cannot have mixed/variant data types, e.g.
+
+When defined as
+```protobuf
+message {
+   map<string, string> headers = 1;
+}
+```
+
+All values must be string, so timeout value has to be quoted:
+```yaml
+headers:
+   api_key: abcd
+   timeout: "1000"
+```
+
+- Maps do not support `oneof`, so something like this cannot be expressed as map of different types of messages. 
+
+```yaml
+exporters:
+   otlp:
+      endpoint: http://some_url
+      protocol: http/protobuf
+   zipkin:
+      endpoint: http://another_url
+      timeout: 1000
+```
+Instead, each exporter type will have to be defined as a separate field of the Exporters message:
+
+```protobuf
+message Exporters {
+   OtlpExporter otlp = 1;
+   ZipkinExporter zipkin = 2;
+}
+```
+
+- There is no way to define required fields.