🚀 Google Cloud Pub/Sub Setup Guide

This guide will walk you through setting up Google Cloud Pub/Sub step-by-step, including creating a service account, assigning roles, creating a topic, publishing messages, subscribing to them, and verifying the setup. A flowchart is also included to visualize the process.

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🌟 Step 1: Create a Service Account

gcloud iam service-accounts create pubsub-sa \
    --display-name "Pub/Sub Service Account"

✅ Expected Output:

• A confirmation message will come

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🌟 Step 2: Get the Service Account Email

List all service accounts

gcloud iam service-accounts list

✅ Expected Output:

• A table displaying the service account's email, unique ID, and description.

Example:

NAME         EMAIL                                 DISABLED
pubsub-sa    pubsub-sa@your-project-id.iam.gserviceaccount.com  False

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🌟 Step 3: Assign Roles to the Service Account

You need to assign permissions to the service account for Pub/Sub.

👉 For Publishing

Assign the pubsub.publisher role:

gcloud projects add-iam-policy-binding [PROJECT_ID] \
    --member="serviceAccount:[SERVICE_ACCOUNT_EMAIL]" \
    --role="roles/pubsub.publisher"

👉 For Subscribing

Assign the pubsub.subscriber role:

gcloud projects add-iam-policy-binding [PROJECT_ID] \
    --member="serviceAccount:[SERVICE_ACCOUNT_EMAIL]" \
    --role="roles/pubsub.subscriber"

👉 For Full Admin Control

(If needed for managing topics, subscriptions, and permissions):

gcloud projects add-iam-policy-binding [PROJECT_ID] \
    --member="serviceAccount:[SERVICE_ACCOUNT_EMAIL]" \
    --role="roles/pubsub.admin"

✅ Expected Output:

• A message confirming the IAM policy update.

Example:

Updated IAM policy for project [devops01-450518].
bindings:
- members:
  - serviceAccount:pubsub-sa@your-project-id.iam.gserviceaccount.com
  role: roles/pubsub.admin
etag: BwYv0gyiths=
version: 1

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🌟 Step 4: Create a Pub/Sub Topic

Create a new topic where messages will be published:

gcloud pubsub topics create my-topic

✅ Expected Output:

• A confirmation message showing the topic was created.

Example:

Created topic [projects/your-project-id/topics/my-topic].

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🌟 Step 5: Publish a Message to the Topic

Send a message to the topic:

gcloud pubsub topics publish my-topic --message "Hello, Pub/Sub!"

✅ Expected Output:

• A confirmation message showing the message was published.

Example:

Message published.

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🌟 Step 6: Create a Subscription

Create a subscription to receive messages from the topic:

gcloud pubsub subscriptions create my-subscription \
    --topic=my-topic

✅ Expected Output:

• A confirmation message showing the subscription was created.

Example:

Created subscription [projects/your-project-id/subscriptions/my-subscription].

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🌟 Step 7: Pull Messages from the Subscription

Retrieve messages from the subscription:

gcloud pubsub subscriptions pull my-subscription --auto-ack

✅ Expected Output:

• The message content will be displayed in the terminal.

Example:

Received message: ID=123456789123456789
Data: 'Hello, Pub/Sub!'

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🌟 Step 8: Verify the Setup

To verify the roles and permissions:

gcloud projects get-iam-policy [PROJECT_ID]

✅ Expected Output:

• A list showing the assigned roles to the service account.

Example:

bindings:
- members:
  - serviceAccount:pubsub-sa@your-project-id.iam.gserviceaccount.com
  role: roles/pubsub.publisher
- members:
  - serviceAccount:pubsub-sa@your-project-id.iam.gserviceaccount.com
  role: roles/pubsub.subscriber

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🔥 Flowchart: How Pub/Sub Works

Here’s how the entire process works:

1. Create a Service Account.
2. Assign Roles (Publisher/Subscriber/Admin).
3. Create a Topic.
4. Create a Subscription linked to the topic.
5. Publish Messages to the topic.
6. Pull Messages from the subscription.
7. Verify the setup and roles.

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graph TD;
    A[Create Service Account] --> B[Assign Roles];
    B --> C[Create Topic];
    C --> D[Create Subscription];
    D --> E[Publish Message];
    E --> F[Pull Message];
    F --> G[Verify Setup];

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