Initial code check-in

.dockerignore

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+**/__pycache__
+**/.classpath
+**/.dockerignore
+**/.env
+**/.git
+**/.gitignore
+**/.project
+**/.settings
+**/.toolstarget
+**/.vs
+**/.vscode
+**/*.*proj.user
+**/*.dbmdl
+**/*.jfm
+**/azds.yaml
+**/bin
+**/charts
+**/docker-compose*
+**/Dockerfile*
+**/node_modules
+**/npm-debug.log
+**/obj
+**/secrets.dev.yaml
+**/values.dev.yaml
+README.md

Dockerfile

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+# For more information, please refer to https://aka.ms/vscode-docker-python
+FROM python:3.8-slim-buster
+
+# Keeps Python from generating .pyc files in the container
+ENV PYTHONDONTWRITEBYTECODE 1
+
+# Turns off buffering for easier container logging
+ENV PYTHONUNBUFFERED 1
+
+# Install pip requirements
+ADD requirements.txt .
+RUN python -m pip install -r requirements.txt
+
+WORKDIR /app
+ADD . /app
+
+# Switching to a non-root user, please refer to https://aka.ms/vscode-docker-python-user-rights
+# RUN useradd appuser && chown -R appuser /app
+# USER appuser
+
+EXPOSE 8080
+
+# During debugging, this entry point will be overridden. For more information, please refer to https://aka.ms/vscode-docker-python-debug
+CMD ["python", "dockstat.py"]
+
+HEALTHCHECK --interval=30s --timeout=3s --retries=1 \
+  CMD python3 /app/dockstat.py --healthcheck

dockstat.py

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+#!/usr/bin/env python3
+"""
+Module to act as a Prometheus Exporter for Docker containers with a
+    healthcheck configured
+"""
+
+import argparse
+import http.server
+import os.path
+import socketserver
+import sys
+import time
+
+import docker
+
+LISTEN_PORT = 8080
+HEALTHY_STR = 'healthy'
+
+
+class SimpleHTTPRequestHandler(http.server.BaseHTTPRequestHandler):
+    """
+    Class to encompass the requirements of a Prometheus Exporter
+        for Docker containers with a healthcheck configured
+    """
+    # pylint: disable=invalid-name
+    def do_GET(self):
+        """
+        Method to handle GET requests
+        """
+        if self.path == '/metrics':
+            self._metrics()
+
+        if self.path == '/healthcheck':
+            self._healthcheck()
+
+
+    def _healthcheck(self, message=True):
+        """
+        Method to return 200 or 500 response and an optional message
+        """
+        if not healthy():
+            self.send_response(500)
+            self.end_headers()
+            if message:
+                self.wfile.write(b'ERR')
+            return
+
+        self.send_response(200)
+        self.end_headers()
+        if message:
+            self.wfile.write(b'OK')
+
+
+    def _metrics(self):
+        """
+        Method to handle the request for metrics
+        """
+        self._healthcheck(message=False)
+
+        api = docker.APIClient()
+
+        client = docker.from_env()
+        for container in client.containers.list():
+            now = int(round(time.time() * 1000))
+            data = api.inspect_container(container.id)
+
+            try:
+                health_str = data["State"]["Health"]["Status"]
+            except KeyError:
+                pass
+            else:
+                self.wfile.write(
+                    bytes(
+                        f'container_inspect_state_health_status{{'
+                        f'id="{container.id}",'
+                        f'name="{container.name}",'
+                        f'value="{health_str}"'
+                        f'}} '
+                        f'{int(health_str == HEALTHY_STR)} {now}\n'.encode()
+                    )
+                )
+
+
+def healthy():
+    """
+    Simple funtion to return if all the requirements are met
+    """
+    return all([
+        os.path.exists('/var/run/docker.sock'),
+    ])
+
+
+if __name__ == '__main__':
+    def cli_parse():
+        """
+        Function to parse the CLI
+        """
+        parser = argparse.ArgumentParser()
+
+        parser.add_argument(
+            '-H', '--healthcheck',
+            action='store_true',
+            help='Simply exit with 0 for healthy or 1 when unhealthy',
+        )
+
+        return parser.parse_args()
+
+
+    def main():
+        """
+        main()
+        """
+        args = cli_parse()
+
+        if args.healthcheck:
+            # Invert the sense of 'healthy' for Unix CLI usage
+            return not healthy()
+
+        Handler = SimpleHTTPRequestHandler
+
+        with socketserver.TCPServer(('', LISTEN_PORT), Handler) as httpd:
+            httpd.serve_forever()
+
+        return True
+
+    sys.exit(main())

requirements.txt

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+# To ensure app dependencies are ported from your virtual environment/host machine into your container, run 'pip freeze > requirements.txt' in the terminal to overwrite this file
+docker