# Prerequisites

## Kafka versions <a href="#kafka-versions" id="kafka-versions"></a>

Any version of Apache Kafka (2.0 or newer) on-premise and on-cloud.

## Schema Registry <a href="#kafka-versions" id="kafka-versions"></a>

Any version of Confluent Schema Registry (5.5.0 or newer), APICurio (2.0 or newer) and AWS Glue.

## JMX connectivity <a href="#jmx-connectivity" id="jmx-connectivity"></a>

Connectivity to JMX is optional (not required) but recommended for additional/enhanced monitoring of the Kafka Brokers and Connect Workers. Secure JMX connections are also supported, as well as JOLOKIA and OpenMetrics (MSK).

For more enable JMX for Lenses itself see [here](https://github.com/lensesio-dev/docs/blob/master/deployment/prepare-your-environment/jmx-metrics.md).

## Hardware & OS <a href="#hardware--os" id="hardware--os"></a>

Run on any Linux server (review ulimits or container technology (docker/kubernetes). For RHEL 6.x and CentOS 6.x use docker.

Linux machines typically have a soft limit of 1024 open file descriptors. Check your current limit with the `ulimit` command:

```bash
ulimit -S -n     # soft limit
ulimit -H -n     # hard limit
```

Increase as a super-user the soft limit to 4096 with:

```bash
ulimit -S -n 4096
```

Use 6GB RAM/4 CPUs and 500MB disk space.

## Memory & CPU

This is the default configuration = Request `1` CPU & Memory `3Gi`, Limit 2 CPU & Memory `5Gi`

## Browser <a href="#browser" id="browser"></a>

All recent versions of major browsers are fully supported.

### APIs and Websockets <a href="#apis-and-websockets" id="apis-and-websockets"></a>

Every action in Lenses is backed by an API or websocket, documented at [https://api.lenses.io](https://api.lenses.io/). A Golang client is available and CLI (command line interface).

{% hint style="info" %}
For websockets you may need to adjust your loadbalancer to allow them. See [here](https://github.com/lensesio-dev/docs/blob/master/deployment/prepare-your-environment/networking-with-load-balancers.md).
{% endhint %}

## Lenses state store <a href="#lenses-state-store" id="lenses-state-store"></a>

Lenses can use an embedded H2 database or a [Postgres database](https://github.com/lensesio-dev/docs/blob/master/deployment/prepare-your-environment/lenses-metadata-database.md). Postgres is not supplied by Lenses.

## TLS termination <a href="#tls-termination" id="tls-termination"></a>

By default, Lenses does not provide TLS termination but can be enabled via a configuration option. TLS termination is recommended for enhanced security and a prerequisite for integrating with SSO (Single Sign On) via SAML2.0.

TLS termination can be configured directly within Lenses or by using a TLS proxy or load balancer. Refer to the TLS [documentation ](https://github.com/lensesio-dev/docs/blob/master/deployment/prepare-your-environment/enable-tls-on-lenses.md)for additional information.


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