> [!CAUTION]
> **Caution:** This documentation covers Edge for Private Cloud 4.18.01, which is no longer supported. Google does not provide security patches, bug fixes, or technical support for this version. The current supported version is 4.54.00. See the [Edge for Private Cloud documentation](https://docs.apigee.com/private-cloud/latest/overview) for the current version, or [All versions](https://docs.apigee.com/private-cloud/versions) to compare releases.

*Edge for Private Cloud v4.18.01*

Apigee Developer Channel Services is a template portal for content and community management.
It is based on the open source Drupal (www.drupal.org) project. The default setup allows creating
and managing API documentation, forums, and blogs. A built-in test console allows testing of APIs
in real time from within the portal.

Apart from content management, Developer Channel Services has various features for community
management such as manual/automatic user registration and moderating user comments. Role-Based
Access Control (RBAC) model controls the access to features on the Developer Channel Services.
For example, you can enable controls to allow registered user to create forum posts, use test
consoles, and so on.

This version of this document has details specific to version **4.18.01**. Any
references that are specific to previous versions are oversights and should be reported as
bugs.

## Access the Apigee Community for your
questions

The [Apigee Community](https://community.apigee.com/) is a free resource where you
can contact Apigee as well as other Apigee customers with questions, tips, and other issues.
Before posting to the community, be sure to first search existing posts to see if your question
has already been answered.

## Supported Network Topologies

The components of the Apigee Developer Channel Services can be installed in different network
configurations, or topologies, including:

- **Single machine** - All Apigee Developer Channel Services components installed on a single machine.
- **Small** - The Drupal database is installed on a separate machine from the other components.

> [!NOTE]
> **Note:** These topologies are the only topologies supported by Apigee. If you use a different network topology, Apigee might not be able to support it. Contact your account manager or [Apigee
> Support](https://community.apigee.com/content/apigee-customer-support) if you require a custom solution.

The following figure shows the single-machine topology where all components of the Apigee
Developer Channel Services are installed on a single machine:

![](https://docs.apigee.com/static/private-cloud/images/oneMachineFinal_v7.png)

> [!NOTE]
> **Note:**
>
> - On a new install of 4.18.01, the installation script installs Postgres and Nginx.
> - On an update to 4.18.01 from an install that uses Postgres and Nginx, the installation script updates Postgres and Nginx.
> - On an update to 4.18.01 from an install that uses MySQL/MariaDB/Apache, you **must** first convert your installation to Postgres/Nginx before you can update to 4.18.01.

In this figure, the Public core contains the components that are publicly accessible. The
Private core contains components that are not publicly accessible.

|---|---|---|
| **Component** | **Description** | **Installed by** |
| ELB | An Enterprise Load Balancer (ELB). | Your network provider. For example, both Amazon and Rackspace provide Enterprise load balancers for use with their instances. |
| Nginx 1.10.1 | The Nginx web server used for installations of 4.18.01. | Apigee |
| Apache Server Version 2.2 | The Apache web server used in previous versions of the portal. | Apigee |
| Postgres 9.6 | The database used by Drupal for new installations of 4.18.01. | Apigee, or connect to an existing installation. If you want to connect to a remote Postgres installation, it must be version 9.6. |
| MySQL 5.0.15 or later | The database used in previous versions of the portal on RedHat 6.x or CentOS 6.x. | Apigee, or connect to an existing installation. If MySQL is installed by the Apigee installer, it installs the latest version available for your OS. If you want to connect to a remote MySQL installation, it must be version 5.0.15 or later. |
| MariaDB 5.1.38 or later | The database used in previous versions of the portal on RedHat 7.x or CentOS 7.x. | Apigee, or connect to an existing installation. If MariaDB is installed by the Apigee installer, it installs the latest version available for your OS. If you want to connect to a remote MariaDB installation, it must be version 5.1.38 or later. |
| Drupal shared storage | The shared storage area used by Drupal for uploaded files, static scripts, and other information. | Apigee |
| Drush 6.2 | The Drupal command line interface. | Apigee |
| PHP 7.0 | Server-side scripting engine. | Apigee |
| Apache Solr | The Drupal search server. Apache Solr uses the Apache Lucene search library. | Apigee, but it is not enabled by default. Only enable it if you have a large amount of data on the portal. See [Developer Services portal installation](https://docs.apigee.com/private-cloud/v4.18.01/developer-services-portal-installation) for instructions on enabling it. |

Shown below is the small topology where the MySQL server resides on a separate machine:

![](https://docs.apigee.com/static/private-cloud/images/smallTopo_v7.png)