# Google Cloud CDN

## Forward GCP Cloud CDN Access Logs to Limy Analytics

This guide walks you through forwarding Google Cloud CDN access logs to [Limy Analytics](https://limy.ai/) in near real-time.

```
Cloud CDN → Cloud Logging → Log Sink → Pub/Sub Topic → Push Subscription → Limy Analytics
```

Logs flow from Cloud CDN into Cloud Logging automatically. We create a pipeline that routes them to a Pub/Sub topic, which pushes each log entry to Limy Analytics ingestion endpoint within seconds.

***

### Prerequisites

* A GCP project with Cloud CDN and a load balancer already configured
* Cloud Logging API enabled
* Pub/Sub API enabled
* A Limy Analytics account

***

### Step 1: Create a Pub/Sub Topic

1. Open the [Google Cloud Console](https://console.cloud.google.com/)
2. Navigate to **Pub/Sub → Topics**
3. Click **Create Topic**
4. Set the **Topic ID** to - `limy-analytics-topic`
5. Uncheck 'Add a default subscription'
6. Click **Create**

<figure><img src="/files/WsR4h7z9guDJBJc0dKc1" alt=""><figcaption></figcaption></figure>

***

### Step 2: Create a Log Sink

The log sink routes matching log entries from Cloud Logging into the Pub/Sub topic.

1. Navigate to **Logging → Log Router**
2. Click **Create Sink**
3. Fill in the following:

#### Sink Details

| Field     | Value                 |
| --------- | --------------------- |
| Sink name | `limy-analytics-sink` |

Click **Next**.

#### Sink Destination

| Field               | Value                         |
| ------------------- | ----------------------------- |
| Sink service        | **Cloud Pub/Sub topic**       |
| Cloud Pub/Sub topic | Select `limy-analytics-topic` |

Click **Next**.

#### Choose Logs to Include

In the **inclusion filter** field, enter:

**For all load balancer logs:**

```
resource.type="http_load_balancer"
```

**For a specific load balancer**, add a filter on the forwarding rule or URL map name:

```
resource.type="http_load_balancer"
resource.labels.forwarding_rule_name="YOUR_FORWARDING_RULE_NAME"
```

or

```
resource.type="http_load_balancer"
resource.labels.url_map_name="YOUR_URL_MAP_NAME"
```

> **Tip:** To find the exact resource label values for your load balancer, go to **Logs Explorer**, filter by `resource.type="http_load_balancer"`, expand any log entry, and look under `resource.labels`.

**For multiple load balancers**, you can combine filters:

```
resource.type="http_load_balancer"
AND (
  (resource.labels.forwarding_rule_name="MY-FORWARDING-RULE-NAME"
  AND resource.labels.url_map_name="MY-URL-MAP-NAME")
  OR
  (resource.labels.forwarding_rule_name="MY-FORWARDING-RULE-NAME-2"
  AND resource.labels.url_map_name="MY-URL-MAP-NAME-2")
)
```

<figure><img src="/files/QQvPJjAAsYNGlnEPuhZM" alt=""><figcaption></figcaption></figure>

Click **Next**.

#### Choose Logs to Exclude (Optional)

Skip this step or add exclusion filters if needed.

4. Click **Create Sink**

***

### Step 3: Create a Push Subscription

The push subscription sends each message to Limy Analytics automatically.

1. Navigate to **Pub/Sub → Topics →** `limy-analytics-topic`
2. Click **Create Subscription**
3. Fill in the following:

| Field           | Value                       |
| --------------- | --------------------------- |
| Subscription ID | `limy-analytics-push`       |
| Delivery type   | **Push**                    |
| Endpoint URL    | <https://stream.getlimy.ai> |

<figure><img src="/files/kr5mdDwVk0iv5isgFcNu" alt=""><figcaption></figcaption></figure>

#### Add a Transform

The transform injects your Limy Analytics API key into each message and removes unused fields to reduce log export volume and improve performance.

7. Click **Add a Transform**
8. Enter `TransformGcpCdnToLimyFormat` as the function name
9. Paste the following code into the function body:

```javascript
function TransformGcpCdnToLimyFormat(message, metadata) {

    const data = JSON.parse(message.data);
    data['api_key'] = 'YOUR_LIMY_API_KEY';

    // remove unused fields
    delete data['insertId'];
    delete data['jsonPayload'];
    delete data['logName'];
    delete data['receiveTimestamp'];
    delete data['resource'];
    delete data['severity'];
    delete data['spanId'];
    delete data['trace'];

    message.data = JSON.stringify(data);

    return message;

}
```

> **Important:** Replace `YOUR_LIMY_API_KEY` with your actual Limy Analytics API key.

<figure><img src="/files/766aYB8tihSlEB48bt9F" alt=""><figcaption></figcaption></figure>

10. Click **Validate** to ensure the function is valid
11. Click **Create**


---

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