Add uWSGI support (#41)

- Add uWSGI service for testing and as an example
- Add propagation tests for uwsgi directives
- Update example/README.md
- Ignore *.pyc
- Mention uwsgi_pass in the docs for datadog_proxy_directive

Resolves #38

Author: dmehala

.gitignore

@@ -18,3 +18,6 @@
 
 # scratch directory for preparing releases
 /.release/
+
+# Python
+__pycache__/

doc/API.md

@@ -358,8 +358,8 @@ If there is no location associated with the current request, then
 
 ### `datadog_proxy_directive`
 `$datadog_proxy_directive` expands to the name of the configuration directive
-used to proxy the current request, i.e. one of `proxy_pass`, `grpc_pass`, or
-`fastcgi_pass`.
+used to proxy the current request, i.e. one of `proxy_pass`, `grpc_pass`,
+`fastcgi_pass`, or `uwsgi_pass`.
 
 If the request was not configured by one of those directives, then
 `$datadog_proxy_directive` expands to "`location`".

example/README.md

@@ -12,6 +12,7 @@ services:
 - `http` runs a NodeJS HTTP server that listens on port 8080.
 - `fastcgi` runs a NodeJS FastCGI server that listens on port 8080.
 - `grpc` runs a NodeJS gRPC server that listens on port 1337.
+- `uwsgi` runs a Python uWSGI server that listens on port 8080.
 - `client` contains the command line tools `curl` and `grpcurl`.
 
 Because client command line tools are available within the `client` service,

example/docker-compose.yml

@@ -14,6 +14,7 @@ services:
       - http
       - fastcgi
       - grpc
+      - uwsgi
       - agent
 
   # `agent` is the Datadog Agent to which traces are sent.
@@ -69,6 +70,18 @@ services:
     depends_on:
       - agent
 
+  # `uwsgi` is a uWSGI server that is reverse proxied by `nginx`.
+  uwsgi:
+    build:
+      context: ./services/uwsgi
+      dockerfile: ./Dockerfile
+    environment:
+      - DD_ENV=prod
+      - DD_AGENT_HOST=agent
+      - DD_SERVICE=uwsgi
+    depends_on:
+      - agent
+
   # `client` is a container that exists solely so that the host can
   # `docker-compose exec` into it to run command line tools such as `curl` and
   # `grpcurl`.  This way, the host's network doesn't need access to the network

example/services/nginx/nginx.conf

@@ -42,6 +42,11 @@ http {
         location /fastcgi {
             fastcgi_pass fastcgi:8080;
         }
+
+        location /uwsgi {
+            include uwsgi_params;
+            uwsgi_pass uwsgi:8080;
+        }
     }
 
     server {

example/services/uwsgi/Dockerfile

@@ -0,0 +1,13 @@
+FROM alpine:3.15
+
+RUN mkdir /opt/app
+WORKDIR /opt/app
+
+RUN apk update && apk add python3 py3-pip python3-dev build-base linux-headers pcre-dev
+RUN pip3 install --no-cache-dir uwsgi flask ddtrace
+
+COPY ./uwsgi.ini /opt/app/uwsgi.ini
+COPY ./wsgi.py /opt/app/wsgi.py
+COPY ./app.py /opt/app/app.py
+
+CMD ["uwsgi", "--ini", "uwsgi.ini"]

example/services/uwsgi/app.py

@@ -0,0 +1,14 @@
+from flask import Flask, request, jsonify
+
+app = Flask(__name__)
+
+@app.route("/", defaults={"path": ""})
+@app.route("/<string:path>")
+@app.route("/<path:path>")
+def main(path):
+   response = {
+      "service": "uwsgi",
+      "headers": dict(request.headers)
+   }
+   print(response)
+   return jsonify(response)

example/services/uwsgi/uwsgi.ini

@@ -0,0 +1,11 @@
+[uwsgi]
+module = wsgi:app
+master = true
+socket = :8080
+
+;; dd-trace-py is used to trace the Flask application.
+;; It requires these options to supports uWSGI.
+;; See <https://ddtrace.readthedocs.io/en/stable/advanced_usage.html#uwsgi>.
+enable-threads = 1
+lazy-apps = 1
+import=ddtrace.bootstrap.sitecustomize

example/services/uwsgi/wsgi.py

@@ -0,0 +1,4 @@
+from app import app
+
+if __name__ == "__main__":
+    app.run()

module/config

@@ -6,6 +6,6 @@ ngx_module_name="$ngx_addon_name"
 # configuration directives we override.  This way, our module can define
 # handlers for those directives that do some processing and then forward
 # to the "real" handler in the other module.
-ngx_module_order="$ngx_addon_name ngx_http_log_module ngx_http_fastcgi_module ngx_http_grpc_module ngx_http_proxy_module ngx_http_api_module"
+ngx_module_order="$ngx_addon_name ngx_http_log_module ngx_http_fastcgi_module ngx_http_grpc_module ngx_http_proxy_module ngx_http_api_module ngx_http_uwsgi_module"
 
 . auto/module