Consumer group monitoring is a key part of operating Kafka. Lenses allows operators to view and manage consumer groups.

Viewing consumer groups

To view consumer groups and the max and min lag across the partitions go to Workspace->Monitor->Consumers. You can also see this information for each topic in the Explore screen->Select topic->Partition tab.

View consumer group details

Select, or search for a consumer group, you can also search for consumer groups that are not active.

Viewing alerts for a consumer group

To view alerts for a consumer group, click the view alerts button. Resetting consumer groups is only possible if the consumer group is not active. i.e. the application must be stopped, such as a Connector or SQL Processor. Enable the show inactive consumers to find them.​​

Resetting consumer group for a specific partition to an offset

1. Select the consumer group

2. Select the partition to reset the offsets for

3. Specify the offset

Resetting the whole consumer group

To reset a consumer group (all clients in the group), select the consumer groups, select Actions, and Change Multiple offsets. This will reset all clients in the consumer group to either:

1. To the start

2. To the last offset

3. To a specific timestamp

Alerts are sent to channels.

AWS Cloud Watch

To send alerts to AWS Cloud Watch, you first need an AWS connection. Go to Admin->Connections->New Connection->AWS. Enter your AWS Credentials.

Next, go to Admin->Alerts->Channels->New Channel->AWS Cloud Watch.

Select an AWS connection.

Datadog

To send alerts to Datadog, you first need a Datadog connection. Go to Admin->Connections->New Connection->DataDog. Enter your API, Application Key and Site.

Next, go to Admin->Alerts->Channels->New Channel->Data Dog.

Select a DataDog connection.

Pager Duty

To send alerts to Pager Duty, you first need a Pager Duty connection. Go to Admin->Connections->New Connection->PagerDuty. Enter your Service Integration Key.

Next, go to Admin->Alerts->Channels->New Channel->Pager Duty.

Select the pager duty connection.

Prometheus Alert Manager

To send alerts to Pager Duty, you first need a Pager Duty connection. Go to Admin->Connections->New Connection->Prometheus.

1. Select your Prometheus connection

2. Set the Source

3. Set the GeneratorURL for your Alert Manager instance

Slack

To send alerts to Slack, you first need a Slack connection. Go to Admin->Connections->New Connection->Slack. Enter your Slack webhook URL.

Next, go to Admin->Alerts->Channels->New Channel->Slack.

Enter the Slack channel you want to send alerts to.

Webhook

Webhooks allow you to send alerts to any service implementing them, they are very flexible.

First, you need a Webhook connection. Go to Admin->Connections->New Connection

Enter the URL, port and credentials.

Create a Channel to use the connection. Go to Admin->Alerts->Channels->New Channel.

1. Choose a name for your Channel instance.

2. Select your connection.

3. Set the HTTP method to use.

4. Set the Request pathA URI0 encoded request path, which may include a query string. Supports alert-variable interpolation.

5. Set the HTTP Headers

6. Set the Body payload

Template variables

In Request path, HTTP Headers and Body payload there is a possibility of using template variables, which will be translated to alert specific fields. To use template variables, you have to use this format: {{VARIABLE}}, i.e. {{LEVEL}}.

Supported template variables:

• LEVEL - alert level (INFO, LOW, MEDIUM, HIGH, CRITICAL).

• CATEGORY - alert category (Infrastructure, Consumers, Kafka Connect, Topics, Producers).

• INSTANCE - (broker url / topic name etc.).

• SUMMARY - alert summary - same content in the Alert Events tab.

• TIMESTAMP

• ID - alert global id (i.e. 1000 for BrokerStatus alert).

• CREDS - CREDS[0] etc. - variables specified in connections Credentials as a list of values separated by a comma.

Webhook Email

To configure real-time email alerts you can leverage Webhooks, for example with the following service:

• Twilio and SendGrid

• Zapier

SendGrid Example

1. Create a webhook connection, for SendGrid with api.sendgrid.com as the host and enable HTTPS

2. Configure a channel to use the connect you just created

3. Set the method to Post

4. Set the request path to the webhook URL from your Zapier account

5. Set the Headers to

1. Set the payload to be

{
  "personalizations":[{
    "to":[{
      "email":"devops@mycompany.com",
      "name":"DevOps & SRE team | MyCompany"
    }],
    "subject":"PRODUCTION | Streaming Data Platform Alert"
  }],
  "content":[{
    "type":"text/html",
    "value":"<html><body><p>Priority Level:{{LEVEL}}</br></br>Category: {{CATEGORY}}</br><br>Description: {{SUMMARY}}</br><small>Alert ID: {{ID}}</small></p></body></html>"
  }],
  "from":{
    "email":"sender-email-address",
    "name":"sender name ie. PRODUCTION | Streaming Data"
  },
  "reply_to":{
    "email":"reply-to-email-address",
    "name":"reply to name"
  }
}

Change the above payload according to your requirements, and remember that the [sender-email-address] needs to be the same email address you registered during the Sender Authentication Sendgrid setup process.

Zapier Example

1. Create a webhook connection, for SendGrid with hooks.zapier.com as the host and enable HTTPS

2. Configure a channel to use the connect you just created

3. Set the method to Post

4. Set the request path tp /v3/mail/send

5. Set the request path to the webhook URL from your Zapier account

6. Set the Headers to:

X-Api-Token: {{CREDS[0]}

1. Set the payload to be

<html>
  <body>
    <h2>Streaming data platform - alert</h2>
    <p>Environment: <a href="http://enjoy.lenses.io"><b>PRODUCTION</b></a></p>
    <p>Priority Level: <b>{{LEVEL}}</b></p>
    <p>Category: <b>{{CATEGORY}}</b></p>
    <p>Summary: {{SUMMARY}}</p>
    <p>Alert ID: {{ID}}</p>
    <p><small>Lenses.io</small></p>
  </body>
</html>

Webhook MS Teams

To create a webhook in your MS Teams workspace you can use this guide.

At the end of the process you get a url of the format: https://YOUR_URL.webhook.office.com/webhook2/<secret-token-by-ms>/IncomingWebhook/<secret-token-by-ms>

You’ll need the second part

/webhook2/<secret-token-by-ms>/IncomingWebhook/<secret-token-by-ms>

1. Create a new Webhook Connection, set the host to outlook.office.com and enable HTTPS

2. Configure an new channel, using this connection

3. Set the Method to POST

4. The Request Path to the second part of the URL you recieved from MS Teams

/webhook2/<secret-token-by-ms>/IncomingWebhook/<secret-token-by-ms>

1. In the body set

{"text": "{{CATEGORY}} {{LEVEL}} {{ID}}"}

Webhook SMS

See Zapier and follow blog post SMS alerts with Zapier.

Alerts rules are configurable in Lenses, alerts that are generated can then be sent to specific channels. Several different integration points are available for .

Infrastructure alerts

These are a set of built-in alerting rules for the core connections, Kafka, Schema Registry, Zookeeper, and Kafka Connect. See .

Data Produced Alerts

Data produced are user-defined alerts on the amount of data on a topic over time. Users have a choice to notify if the topic receives either:

1. more than

2. or less than

Consumer lag alerts

Consumer rules are alerting on consumer group lag. Users can define:

1. a lag

2. on a topic

3. for a consumer group

4. which channels to send an alert to

Application alerts

Lenses allows operators to configure alerting on Connectors. Operators can:

1. Set channels to send alerts to

2. Enable auto restart of connector tasks. Lenses will restart failed tasks with a grace period.

The sequence is:

1. Lenses watches for task failures.

2. If a task fails, Lenses will restart it.

3. If the restart is successful Lenses resets the "restart attempts" back to zero

4. If the restart is not successful, Lenses increments the restart attempts, waits for the grace period and tries another restart if the task is still in a failed state.

Steps 4 is repeated until restart attempts is reached. Lenses will only rest the restart attempts to zero after the tasks have been brought back to a healthy start by manual intervention.

The number of times Lenses attempts to restart is based on the entry in the alert setting.

Viewing alert events

To view events go to Admin -> Alerts -> Events.

Lenses provides monitoring of the health of your infrastructure via JMX.

Additionally, Lenses has a number of built-in for these services.

Monitoring alerts

Lenses monitors (by default every 10 seconds) your entire streaming data platform infrastructure and has the following alert rules built-in:

Broker decommissioning

If you change your Kafka cluster size or replace an existing Kafka broker with another, Lenses will raise an active alert as it will detect that a broker of your Kafka cluster is no longer available. If the Kafka broker has been intentionally removed, then decommission it:

1. Navigate to Services.

2. Select the broker, click on the actions in the options menu and click on the Decommission option.