参考にしたページ
Publishing Messages
Subscribing to Messages

プログラムを実行するには、
認証の JSON ファイルが必要です。
この　例では、my-project-sep-10-2017.json　としました。

この JSON　(サービスアカウントキー）は、google console で作成してダウンロードします。

トピックの作成

create_topic.py

# ! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	create_topic.py
#
#						Feb/08/2018
# ------------------------------------------------------------------
import	sys	
from google.cloud import pubsub

# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
publisher = pubsub.PublisherClient()

project_id = 'my-project-sep-10-2017'
topic_name = 'topic_1'
topic_path = publisher.topic_path(project_id,topic_name)

try:
	topic = publisher.create_topic(topic_path)
	print('Topic created: {}'.format(topic))
except Exception as ee:
	sys.stderr.write("*** error *** in publisher.create_topic ***\n")
	sys.stderr.write(str(ee) + "\n")

sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

実行スクリプト

export GOOGLE_APPLICATION_CREDENTIALS="./my-project-sep-10-2017.json"
./create_topic.py

サブスクリプションの作成

create_subscribe.py

# ! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	create_subscribe.py
#
#						Feb/08/2018
# ------------------------------------------------------------------
import	sys	
from google.cloud import pubsub
# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
subscriber = pubsub.SubscriberClient()

topic_name = 'projects/my-project-sep-10-2017/topics/topic_1'
sub_name = 'projects/my-project-sep-10-2017/subscriptions/subscription_1'

try:
	subscriber.create_subscription(sub_name, topic_name)
except Exception as ee:
	sys.stderr.write("*** error *** in subscriber.create_subscription ***\n")
	sys.stderr.write(str(ee) + "\n")

#
sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

実行スクリプト

export GOOGLE_APPLICATION_CREDENTIALS="./my-project-sep-10-2017.json"
./create_subscribe.py

パブリッシュ

iot_publish.py

# ! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	iot_publish.py
#
#						Feb/08/2018
# ------------------------------------------------------------------
import	sys	
import	datetime
from google.cloud import pubsub
# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
publisher = pubsub.PublisherClient()

project_id = 'my-project-sep-10-2017'
topic_name = 'topic_1'
topic_path = publisher.topic_path(project_id,topic_name)

dd = datetime.datetime.today()
message = 'This is my message. ' + dd.strftime("%Y-%m-%d %H:%M:%S") 
sys.stderr.write(message + "\n")

message_bb = message.encode()

publish_client = pubsub.PublisherClient()
publish_client.publish(topic_path, message_bb)

sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

実行スクリプト

export GOOGLE_APPLICATION_CREDENTIALS="./my-project-sep-10-2017.json"
./iot_publish.py

サブスクライブ

iot_subscribe.py

# ! /usr/bin/python
# -*- coding: utf-8 -*-
#
#	iot_subscribe.py
#
#						Feb/08/2018
# ------------------------------------------------------------------
import	sys	
from google.cloud import pubsub
# ------------------------------------------------------------------
def callback(message):
	print(message)  # Replace this with your actual logic.
	message.ack()
#
# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
subscriber = pubsub.SubscriberClient()

sub_name = 'projects/my-project-sep-10-2017/subscriptions/subscription_1'

subscription = subscriber.subscribe(sub_name)

future = subscription.open(callback)

try:
	try:
		future.result()
	except Exception as ex:
		subscription.close()
		sys.stderr.write(str(ex) + "\n")
except KeyboardInterrupt:
	sys.stderr.write('*** interrupted! ***\n')
#
sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

実行スクリプト

export GOOGLE_APPLICATION_CREDENTIALS="./my-project-sep-10-2017.json"
./iot_subscribe.py