# Heroku logs

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Use our [logging add-on](https://elements.heroku.com/addons/coralogix) to seamlessly forward all [Heroku logging](https://coralogix.com/blog/heroku-logs-the-complete-guide/) output to Coralogix.

This tutorial demonstrates how to:

* Create a [sample application](#sample-application)

* Configure your Heroku Shield private space to send logs to Coralogix

* Attach multiple Heroku apps to one Coralogix account

## Overview[​](#overview "Direct link to Overview")

### Logging add-on[​](#logging-add-on "Direct link to Logging add-on")

Coralogix offers a logging add-on that forwards all Heroku output to a Coralogix account that you specify. Alternatively, you can use the [CLI](https://docs-docusaurus.kinsta.page/developer-portal/infrastructure-as-code/cli/cxctl-legacy/.md) with the following:

`heroku addons:create coralogix:test`

Within seconds, any logs that your application generates will feed right into Coralogix, paving the way for using our high scale, high-speed search, and analytics.

### Extension package[​](#extension-package "Direct link to Extension package")

In addition, Coralogix offers an extension package for Heroku logging that includes a set of Heroku parsing rules to parse the unstructured data streaming from your Heroku app, a set of predefined Heroku alerts, and a predefined dashboard for your Heroku Router logs. What you will need to do to get those is go to Coralogix [Extension Packages](https://coralogix.com/tutorials/extension-packages/) and deploy the Heroku extension package and then, with a click of a button, you will get tremendous value out of your Heroku Router logs.

Here's a basic example that shows that even with a small application generating simple log records, as soon it starts scaling, logs become hard to traverse and understand.

## Sample application[​](#sample-application "Direct link to Sample application")

The sample application consists of a [Python](https://elements.heroku.com/addons/coralogix) and [Ruby](https://github.com/ChrisChinchilla/ruby-cats) application that randomly generates a Cat from the Cat API every 2 seconds and logs the value.

I started with one instance of each, then scaled to three instances. Here are the logs using `heroku logs` on one instance.

[![one worker sending logs to coralogix](/assets/images/one-worker-1024x704-6e96fc0ef644ad9cea8902974490e2c2.jpg)](https://docs-docusaurus.kinsta.page/assets/images/one-worker-1024x704-6e96fc0ef644ad9cea8902974490e2c2.jpg)

Here's an example of mixed logs with messages from Heroku, debug messages, and errors. It's already getting confusing.

[![two workers sending logs to Coralogix](/assets/images/mixed-messages-1024x719-536087ce69ff140a901322171dbd345b.jpg)](https://docs-docusaurus.kinsta.page/assets/images/mixed-messages-1024x719-536087ce69ff140a901322171dbd345b.jpg)

Throw in two more workers and tracking down the source of messages becomes even more confusing. The sample application has two applications running three workers each.

[![multiple workers on Coralogix](/assets/images/multiple-workers-1024x719-3244ffb353a0bcb09639a9a49f4e077b.jpg)](https://docs-docusaurus.kinsta.page/assets/images/multiple-workers-1024x719-3244ffb353a0bcb09639a9a49f4e077b.jpg)

We can do this a lot more efficiently using Coralogix. To begin, open the [dashboard page](https://dashboard.coralogix.com/#/dashboard), or use the CLI and check the initial display right after you start sending logs:

```
CLI:addons:open coralogix 
```

[![](/assets/images/image-19-1024x612-9eab8cd038fb08a0991bf74b6e7f2700.webp)](https://docs-docusaurus.kinsta.page/assets/images/image-19-1024x612-9eab8cd038fb08a0991bf74b6e7f2700.webp)

[![](/assets/images/image-20-1-1024x576-c96bfa2b4b458190ead854c54a129316.webp)](https://docs-docusaurus.kinsta.page/assets/images/image-20-1-1024x576-c96bfa2b4b458190ead854c54a129316.webp)

After 24 hours, the Coralogix [Loggregation](https://coralogix.com/tutorials/what-is-coralogix-loggregation/) feature automatically clusters log entries – which makes finding what you need faster and powers our ML-powered anomalies. In the screenshot below, you can see that Loggregation has identified that despite being 'random', the CatAPI repeats itself a lot, outputting the same value over 1,000 times. In this case, it's not important, but in a mission-critical application, this helps you identify patterns clearly.

[![](/assets/images/image-21-1-1024x498-2ecca809cc8748119b5ac61938161573.webp)](https://docs-docusaurus.kinsta.page/assets/images/image-21-1-1024x498-2ecca809cc8748119b5ac61938161573.webp)

Errors and broken flows are often introduced by new versions and application builds. The Coralogix Heroku integration includes integration to Heroku Pipelines and offers an automatic status for new Heroku builds (i.e. [tags](https://coralogix.com/tutorials/software-builds-display/) in Coralogix). Coralogix presents the suspicious and common errors introduced since that build as well as the alerts and anomalies which might be related to the new version release, thus allowing you to correlate issues to particular versions and points in time.

[![](/assets/images/image-22-1024x556-56c6be853066518faf1e55d6b7929bbc.webp)](https://docs-docusaurus.kinsta.page/assets/images/image-22-1024x556-56c6be853066518faf1e55d6b7929bbc.webp)

[![](/assets/images/image-23-1024x578-d218abb47f54f73eba3b513470b1953b.webp)](https://docs-docusaurus.kinsta.page/assets/images/image-23-1024x578-d218abb47f54f73eba3b513470b1953b.webp)

After 5 days of learning, Coralogix will start to send a daily report highlighting new anomalies (errors and critical messages), further helping you identify new errors, and not constantly bombard you with logging noise.

In addition to the machine learning aspect, Coralogix offers a complete set of logging capabilities, including Log Query, a centralized live tail, user-defined alerts to email or slack, and dashboard creation.

[Provision the Coralogix addon](https://elements.heroku.com/addons/coralogix) and start enjoying 3rd generation Log analytics

## Private space logging[​](#private-space-logging "Direct link to Private space logging")

You may configure your Heroku Shield private space to send logs to Coralogix by pointing the [Heroku log drain](https://devcenter.heroku.com/articles/log-drains#https-drains) to the appropriate Coralogix destination.

Note

This approach is not supported on Heroku's Fir generation. Use [Heroku Telemetry Drain](https://docs-docusaurus.kinsta.page/integrations/paas-platforms/heroku/heroku-telemetry-drains/.md) instead.

### Prerequisites[​](#prerequisites "Direct link to Prerequisites")

* [Coralogix Company ID](https://docs-docusaurus.kinsta.page/user-guides/account-management/account-settings/team-id/.md)
* [Send-Your-Data API Key](https://docs-docusaurus.kinsta.page/user-guides/account-management/api-keys/send-your-data-api-key/.md) (Private Key)
* Choose the
  <!-- -->
  https\://ingress. endpoint that corresponds to your Coralogix [domain](https://docs-docusaurus.kinsta.page/user-guides/account-management/account-settings/coralogix-domain/.md) using the domain selector at the top of the page

### Endpoint URL format[​](#endpoint-url-format "Direct link to Endpoint URL format")

The log drain URL uses HTTP Basic Authentication with your Company ID as the username and your Private Key as the password:

```
https://<CompanyId>:<PrivateKey>@https://ingress.eu2.coralogix.com/heroku/v1/private?appName=<applicationName>
```

### Query parameters[​](#query-parameters "Direct link to Query parameters")

| Parameter   | Required | Description                                                                                                                               |
| ----------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| `appName`   | Yes      | The application name that will appear in Coralogix. If not provided, defaults to `default`.                                               |
| `subsName`  | No       | Override the subsystem name for all logs. By default, the subsystem name is extracted from the Heroku process ID (e.g., `web`, `worker`). |
| `cxf_<key>` | No       | Custom fields to append to log messages. See [Custom fields](#custom-fields) below.                                                       |

### Content-Type requirements[​](#content-type-requirements "Direct link to Content-Type requirements")

The log drain must send logs with one of the following Content-Type headers:

* `application/logplex-1` (standard Heroku log drain format)
* `text/plain`

### Adding and removing log drains[​](#adding-and-removing-log-drains "Direct link to Adding and removing log drains")

**Add a log drain:**

```
heroku drains:add "https://<CompanyId>:<PrivateKey>@https://ingress.eu2.coralogix.com/heroku/v1/private?appName=<applicationName>" -a myapp
```

**Remove a log drain:**

```
heroku drains:remove "https://<CompanyId>:<PrivateKey>@https://ingress.eu2.coralogix.com/heroku/v1/private?appName=<applicationName>" -a myapp
```

Find out how to find Heroku messages from a specific app [here](https://devcenter.heroku.com/articles/private-space-logging#find-log-messages-from-a-specific-heroku-app).

### Custom fields[​](#custom-fields "Direct link to Custom fields")

You can add custom fields to your log messages by including query parameters prefixed with `cxf_`. These fields are appended to the log message body as key-value pairs.

**Constraints:**

* Maximum 20 custom fields per request
* Field key (after `cxf_` prefix): alphanumeric characters, underscores (`_`), and hyphens (`-`) only, maximum 64 characters
* Field value: maximum 256 characters

**Example:**

```
https://<CompanyId>:<PrivateKey>@https://ingress.eu2.coralogix.com/heroku/v1/private?appName=myapp&cxf_env=production&cxf_region=us-east-1
```

This appends `env=production region=us-east-1` to each log message.

Note

Custom fields are only appended to text log messages. They are not merged into JSON-converted metric logs.

### Subsystem name override[​](#subsystem-name-override "Direct link to Subsystem name override")

By default, the subsystem name is derived from the Heroku process type (e.g., `web.1` becomes subsystem `web` with thread ID `1`). You can override this for all logs from a drain by setting the `subsName` parameter:

```
https://<CompanyId>:<PrivateKey>@https://ingress.eu2.coralogix.com/heroku/v1/private?appName=myapp&subsName=my-custom-subsystem
```

## ​Attaching multiple apps to a single Coralogix account[​](#attaching-multiple-apps-to-a-single-coralogix-account "Direct link to ​Attaching multiple apps to a single Coralogix account")

You can add multiple apps to the same Coralogix account you created when provisioning your first Heroku app with the Coralogix add-on. All apps will have a unified billing and you will be able to filter by our tag of "application name".

To attach multiple apps to the same Coralogix account using CLI, [follow this link](https://devcenter.heroku.com/articles/managing-add-ons#using-the-command-line-interface-attaching-an-add-on-to-another-app). Or from your Heroku dashboard: configure addons -> open details for Coralogix -> attach another app.

## Sending Heroku Metric Logs to Coralogix[​](#sending-heroku-metric-logs-to-coralogix "Direct link to Sending Heroku Metric Logs to Coralogix")

Coralogix automatically parses Heroku Metric logs into JSON documents, to make analysis and parsing much easier. A more in depth explanation is [available here](https://docs-docusaurus.kinsta.page/integrations/paas-platforms/heroku/heroku-metric-logs/.md).

#### Note[​](#note "Direct link to Note")

Removing your parent Heroku app, to which Coralogix was provisioned originally, will remove the Coralogix addon from all other apps that were attached to this Coralogix account in the past.

## Additional resources[​](#additional-resources "Direct link to Additional resources")

|                         |                                                                                                                                                |
| ----------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- |
| Coralogix Endpoints     | [Coralogix Endpoints](https://docs-docusaurus.kinsta.page/integrations/coralogix-endpoints/.md)                                                |
| Heroku Log Drains       | [Heroku Log Drains Documentation](https://devcenter.heroku.com/articles/log-drains)                                                            |
| Heroku Telemetry Drains | [Heroku Telemetry Drains (Fir generation)](https://docs-docusaurus.kinsta.page/integrations/paas-platforms/heroku/heroku-telemetry-drains/.md) |