Merge branch '337313-expand-the-content-of-the-top-level-infra-page' into 'master'

Resolve "Expand the content of the top level Infra page"

See merge request gitlab-org/gitlab!67671

doc/user/infrastructure/index.md

@@ -6,9 +6,53 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 # Infrastructure management **(FREE)**
-GitLab provides you with great solutions to help you manage your
-infrastructure:
-- [Infrastructure as Code and GitOps](iac/index.md)
-- [Kubernetes clusters](../project/clusters/index.md)
-- [Runbooks](../project/clusters/runbooks/index.md)
+With the rise of DevOps and SRE approaches, infrastructure management becomes codified,
+automatable, and software development best practices gain their place around infrastructure
+management too. On one hand, the daily tasks of classical operations people changed
+and are more similar to traditional software development. On the other hand, software engineers
+are more likely to control their whole DevOps lifecycle, including deployments and delivery.
+GitLab offers various features to speed up and simplify your infrastructure management practices.
+
+## Generic infrastructure management
+
+GitLab has deep integrations with Terraform to run your infrastructure as code pipelines
+and support your processes. Terraform is considered the standard in cloud infrastructure provisioning.
+The various GitLab integrations help you:
+
+- Get started quickly without any setup.
+- Collaborate around infrastructure changes in merge requests the same as you might
+  with code changes.
+- Scale using a module registry.
+
+Read more about the [Infrastructure as Code features](iac/index.md), including:
+
+- [The GitLab Managed Terraform State](terraform_state.md).
+- [The Terraform MR widget](mr_integration.md).
+- [The Terraform module registry](../packages/terraform_module_registry/index.md).
+
+## Integrated Kubernetes management
+
+GitLab has special integrations with Kubernetes to help you deploy, manage and troubleshoot
+third-party or custom applications in Kubernetes clusters. Auto DevOps provides a full
+DevSecOps pipeline by default targeted at Kubernetes based deployments. To support
+all the GitLab features, GitLab offers a cluster management project for easy onboarding.
+The deploy boards provide quick insights into your cluster, including pod logs tailing.
+
+The recommended approach to connect to a cluster is using [the GitLab Kubernetes Agent](../clusters/agent/index.md).
+
+Read more about [the Kubernetes cluster support and integrations](../project/clusters/index.md), including:
+
+- Certificate-based integration for [projects](../project/clusters/index.md),
+  [groups](../group/clusters/index.md), or [instances](../instance/clusters/index.md).
+- [Agent-based integration](../clusters/agent/index.md). **(PREMIUM)**
+  - The [Kubernetes Agent Server](../../administration/clusters/kas.md) is [available on GitLab.com](../clusters/agent/index.md#set-up-the-kubernetes-agent-server)
+    at `wss://kas.gitlab.com`. **(PREMIUM)**
+- [Agent-based access from GitLab CI/CD](../clusters/agent/ci_cd_tunnel.md).
+
+## Runbooks in GitLab
+
+Runbooks are a collection of documented procedures that explain how to carry out a task,
+such as starting, stopping, debugging, or troubleshooting a system.
+
+Read more about [how executable runbooks work in GitLab](../project/clusters/runbooks/index.md).