Creating a Remote Flow with jinad

One common use case in production is running the whole Flow on the remote with pods distributed on different machines. In this case, the very first thing is to ensure all the remote machines have jinad running properly. We will see how to create a remote Flow from the local machine.

Prerequisites

Before the start, make sure you have read the prerequisites for using jinad

Steps

1. Create a Flow

As jinad hosts a service on the remote, we can use the jinad API /flow/yaml to create a Flow via uploading a Flow configuration yaml file. Please refer to the full API specifications for more details.

import requests

def create_flow(flow_url, yamlspec):
    flow_creation_api = f'{flow_url}/flow/yaml/'
    with open(yamlspec, 'rb') as f:
        files = [('yamlspec', f)]
        try:
            r = requests.put(url=flow_creation_api, files=files, timeout=10)
            if r.status_code == requests.codes.ok:
                return r.json()['flow_id']
            else:
                print('Remote Flow creation failed')
        except requests.exceptions.RequestException as ex:
            print(f'Exception raised: {ex!r}')

if __name__ == '__main__':
    host_ip = '3.16.166.3'
    jinad_port = '8000'
    flow_api = f'http://{host_ip}:{jinad_port}'
    flow_id = create_flow(flow_api, 'dummy_flow.yml')
    print(f'flow is created: {flow_id}')

We use a dummy Flow configuration dummy_flow.yml as below for demo purpose.

!Flow
version: 1
pods:
  - name: pod0
    method: add
    uses: _logforward
  - name: pod1
    method: add
    uses: _logforward

After running the above codes, we print out the flow id and please note this flow id for the next step.

flow is created: cdd53e16-5575-11eb-86b2-0ab9db700358

2. Check Flow Status

Before using the Flow we created, we need to get detail information about the Flow so that we can send queries to the Flow. To get the information of the Flow, we can use the following scripts to retrieve the information from /flow/cdd53e16-5575-11eb-86b2-0ab9db700358

import requests

def get_flow_info(flow_url, flow_id):
    flow_info_api = f'{flow_url}/flow/{flow_id}'
    try:
        r = requests.get(url=flow_info_api)
        if r.status_code == requests.codes.ok:
            return str(r.json()["port"])
        else:
            print('Remote Flow info retrieval failed')
    except requests.exceptions.RequestException as ex:
        print(f'Exception raised: {ex!r}')

def main():
    host_ip = '12.34.56.78'
    jinad_port = '8000'
    flow_api = f'http://{host_ip}:{jinad_port}'
    flow_id = 'cdd53e16-5575-11eb-86b2-0ab9db700358'
    flow_port = get_flow_info(flow_api, flow_id)
    print(f'Flow serves at {host_ip}:{flow_port}')

3. Run Index/Query via client

With the host and port information of the remote Flow, we can use the gRPC client of jina to send index or query requests.

from jina.parsers import set_client_cli_parser
from jina.clients import Client
from jina import Document

def send_index_request(host, port):
    print(f'index request sent to {host}:{port}')
    args = set_client_cli_parser().parse_args(
        ['--host', host, '--port-expose', str(port)])
    grpc_client = Client(args)
    grpc_client.index(
        [Document(text='hello, jina'), ], on_done=print)

def main():
    host_ip = '12.34.56.78'
    flow_port = '51871'
    send_index_request(host_ip, flow_port)

4. Terminate Flow

After getting all the work done, we terminate the Flow by sending a DELETE request to the /flow API.

import requests

def delete_flow(flow_api, flow_id):
    flow_deletion_api = f'{flow_api}/flow?flow_id={flow_id}'
    try:
        r = requests.delete(url=flow_deletion_api)
        if r.status_code == requests.codes.ok:
            print('Remote Flow deletion succeeded')
        else:
            print('Remote Flow deletion failed')
    except requests.exceptions.RequestException as ex:
        print(f'Exception raised: {ex!r}')

def main():
    host_ip = '12.34.56.78'
    jinad_port = '8000'
    flow_id = 'cdd53e16-5575-11eb-86b2-0ab9db700358'
    flow_api = f'http://{host_ip}:{jinad_port}'
    delete_flow(flow_api, flow_id)

What’s next?

You many also want to checkout the following articles. Creating a Remote Pod from Console Creating a Remote Pod via Flow APIs