Launch a dataflow template reference

dataflow.py

from __future__ import print_function
from apiclient.discovery import build
from oauth2client import service_account
import httplib2

# https://cloud.google.com/dataflow/docs/templates/executing-templates#example-1-custom-template-batch-job
# https://cloud.google.com/dataflow/docs/reference/rest/v1b3/projects.templates/launch
# https://cloud.google.com/dataflow/docs/templates/executing-templates#using-gcloud

projectId = "my-project-id"
gcsPath = "gs://bucket/folder"
location = "us-central1"

body = {
  "jobName": "my-job-name",
  "parameters": {
    "instanceId": "instance-id",
    "databaseId": "spanner-db-id",
    "outputDir": "gs://bucket/output"
  },
  "environment": {
    "network": "my-network",
    "subnetwork": "regions/us-central1/subnetworks/privatesubnet",
    "maxWorkers": 10,
    "tempLocation": "gs://bucket/tmp"
  }
}


# https://cloud.google.com/dataflow/docs/reference/rest/v1b3/projects.templates/launch#authorization
SCOPES = [
	'https://www.googleapis.com/auth/compute',
    'https://www.googleapis.com/auth/cloud-platform',
    'https://www.googleapis.com/auth/userinfo.email'
]

credentials = service_account.ServiceAccountCredentials.from_json_keyfile_name(
    filename="secret.json", scopes=SCOPES)

http = credentials.authorize(httplib2.Http())

service = build('dataflow', 'v1b3', http=http)

# https://developers.google.com/resources/api-libraries/documentation/dataflow/v1b3/python/latest/dataflow_v1b3.projects.templates.html#launch
results = service.projects().templates().launch(projectId=projectId, location=location, gcsPath=gcsPath, body=body).execute()