How to run a Google Cloud Build trigger via cli / rest api / cloud functions?

I did same thing few days ago.

You can submit your builds using gcloud and rest api

gcloud:

gcloud builds submit --no-source  --config=cloudbuild.yaml --async --format=json

Rest API:

Send you cloudbuild.yaml as JSON with Auth Token to this url https://cloudbuild.googleapis.com/v1/projects/standf-188123/builds?alt=json

example cloudbuild.yaml:

steps:

- name: 'gcr.io/cloud-builders/docker'
  id: Docker Version
  args: ["version"]

- name: 'alpine'
  id:  Hello Cloud Build
  args: ["echo", "Hello Cloud Build"]

example rest_json_body:

{"steps": [{"args": ["version"], "id": "Docker Version", "name": "gcr.io/cloud-builders/docker"}, {"args": ["echo", "Hello Cloud Build"], "id": "Hello Cloud Build", "name": "alpine"}]}

This now seems to be possible via API:

https://cloud.google.com/cloud-build/docs/api/reference/rest/v1/projects.triggers/run

request.json:

{
  "projectId": "*****",
  "commitSha": "************"
}

curl request (with using a gcloud command):

PROJECT_ID="********" TRIGGER_ID="*******************"; curl -X POST -T request.json -H "Authorization: Bearer $(gcloud config config-helper \
    --format='value(credential.access_token)')" \
    https://cloudbuild.googleapis.com/v1/projects/"$PROJECT_ID"/triggers/"$TRIGGER_ID":run

You can use google client api to create build jobs with python:

import operator
from functools import reduce
from typing import Dict, List, Union

from google.oauth2 import service_account
from googleapiclient import discovery


class GcloudService():
    def __init__(self, service_token_path, project_id: Union[str, None]):
        self.project_id = project_id
        self.service_token_path = service_token_path
        self.credentials = service_account.Credentials.from_service_account_file(self.service_token_path)


class CloudBuildApiService(GcloudService):
    def __init__(self, *args, **kwargs):
        super(CloudBuildApiService, self).__init__(*args, **kwargs)

        scoped_credentials = self.credentials.with_scopes(['https://www.googleapis.com/auth/cloud-platform'])
        self.service = discovery.build('cloudbuild', 'v1', credentials=scoped_credentials, cache_discovery=False)

    def get(self, build_id: str) -> Dict:
        return self.service.projects().builds().get(projectId=self.project_id, id=build_id).execute()

    def create(self, image_name: str, gcs_name: str, gcs_path: str, env: Dict = None):
        args: List[str] = self._get_env(env) if env else []
        opt_params: List[str] = [
            '-t', f'gcr.io/{self.project_id}/{image_name}',
            '-f', f'./{image_name}/Dockerfile',
            f'./{image_name}'
        ]
        build_cmd: List[str] = ['build'] + args + opt_params
        body = {
            "projectId": self.project_id,
            "source": {
                'storageSource': {
                    'bucket': gcs_name,
                    'object': gcs_path,
                }
            },
            "steps": [
                {
                    "name": "gcr.io/cloud-builders/docker",
                    "args": build_cmd,
                },
            ],
            "images": [
                [
                    f'gcr.io/{self.project_id}/{image_name}'
                ]
            ],
        }
        return self.service.projects().builds().create(projectId=self.project_id, body=body).execute()

    def _get_env(self, env: Dict) -> List[str]:
        env: List[str] = [['--build-arg', f'{key}={value}'] for key, value in env.items()]
        # Flatten array
        return reduce(operator.iconcat, env, [])

Here is the documentation so that you can implement more functionality: https://cloud.google.com/cloud-build/docs/api

Hope this helps.