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Daemon

Enablement of https://argoproj.github.io/argo-workflows/variables/ This example creates two tasks, one of the Tasks is a deamond task and its IP address is shared with the second task The daemoned task operates as server, serving an example payload, with the second task operating as a client, making http requests to the server.

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from hera.workflows import DAG, Workflow, script


@script(daemon=True)
def server():
    from http.server import BaseHTTPRequestHandler, HTTPServer

    class MyServer(BaseHTTPRequestHandler):
        def do_GET(self):
            self.send_response(200)
            self.send_header("Content-type", "application/json")
            self.end_headers()
            self.wfile.write(bytes("{'name':'John'}", "utf-8"))

    webServer = HTTPServer(("0.0.0.0", 8080), MyServer)
    webServer.serve_forever()


@script()
def consumer(ip):
    import http.client
    import os

    print(os.environ)
    server_ip = ip.replace('"', "")
    connection = http.client.HTTPConnection("{server_ip}:8080".format(server_ip=server_ip))
    connection.request("GET", "/")
    response = connection.getresponse()
    print(response.read())


with Workflow(generate_name="daemon-", entrypoint="d") as w:
    with DAG(name="d"):
        s = server()
        c = consumer(arguments={"ip": s.ip})
        s >> c

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apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: daemon-
spec:
  entrypoint: d
  templates:
  - name: d
    dag:
      tasks:
      - name: server
        template: server
      - name: consumer
        depends: server
        template: consumer
        arguments:
          parameters:
          - name: ip
            value: '{{tasks.server.ip}}'
  - name: server
    daemon: true
    script:
      image: python:3.9
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        from http.server import BaseHTTPRequestHandler, HTTPServer

        class MyServer(BaseHTTPRequestHandler):

            def do_GET(self):
                self.send_response(200)
                self.send_header('Content-type', 'application/json')
                self.end_headers()
                self.wfile.write(bytes("{'name':'John'}", 'utf-8'))
        webServer = HTTPServer(('0.0.0.0', 8080), MyServer)
        webServer.serve_forever()
      command:
      - python
  - name: consumer
    inputs:
      parameters:
      - name: ip
    script:
      image: python:3.9
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        import json
        try: ip = json.loads(r'''{{inputs.parameters.ip}}''')
        except: ip = r'''{{inputs.parameters.ip}}'''

        import http.client
        import os
        print(os.environ)
        server_ip = ip.replace('"', '')
        connection = http.client.HTTPConnection('{server_ip}:8080'.format(server_ip=server_ip))
        connection.request('GET', '/')
        response = connection.getresponse()
        print(response.read())
      command:
      - python

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