nexus

How to use Nexus 3 repository manager on DC/OS

Nexus 3 is a repository manager that supports a broad variety of package managers, namely Bower, Docker, Maven 2, npm, NuGet, PyPI, and Raw site repositories. DC/OS allows you to quickly configure, install and manage a Nexus 3 instance.

• Estimated time for completion: 10 minutes
• Target audience: Anyone interested in running a repository manager.
• Scope: Learn how to install Nexus 3 on DC/OS

Prerequisites

• A running DC/OS 1.8 cluster with at least 1 node having at least 0.5 CPUs and 2 GB of RAM available.
• DC/OS CLI installed.

Install Nexus 3

Assuming you have a DC/OS cluster up and running, we will discuss the installation of Nexus 3 in two variants for persistence. One will be with host volumes, and the other with external persisten volumes. The reason behind that is that the data of the repository / the artifacts need to persisted, so that the Nexus 3 application can be restarted without a data loss.

If you opt to use host volumes, make sure that there is a backup process in place, which will backup the data in the data folder, or that you use a shared filesystem mount (such as NFS) for it.

Host volumes

Let's get started by creating a file called options.json with following contents:

{
  "service": {
    "name": "nexus",
    "cpus": 1,
    "mem": 2048,
    "role": "*",
    "local-volumes": {
      "host-volume": "/opt/nexus",
      "pinned-hostname": "192.168.200.101"
    },
    "external-volumes": {
      "enabled": false
    }
  },
  "networking": {
    "virtual-host": "nexus.dcos.mydomain.mytld"
  }
}

The above options.json file configures Nexus 3 as follows:

• name: This parameter configures the name of the service itself.
• cpus: This parameter configures the number of CPU share to allocate to Nexus 3.
• mem: This parameter configures the amount of RAM to allocate to Nexus 3.
• role: The role which should be used to launch the service. Default is *.
• local-volumes: This parameter configures whether service should use local host volumes. If so, the following properties need to be defined as well:
• host-volume: This is the folder/path which will be mounted in the container, and used to persist the Nexus 3 data on. You need to make sure that the folder exists on the host you used for host pinning, and that it has the appropriate permissions/ownership. You can find a short guide below.
• pinned-hostname: The hostname (or IP address) which should be used to run Nexus 3 on. This is important, because the host-volume folder needs to exist on that host (see above). Replace the value with an actual agent IP address.
• networking: Use this if you want your Nexus 3 service to be available externally.
• virtual-host: Specify the CNAME (or FQDN) of your edge loadbalancer of the DC/OS cluster to be used to expose the service on.

Creating the host volume

To create the host volume, you have to ssh into the host where you want to run the Nexus 3 service on (via host pinning). Then, you should create a folder for the Nexus 3 data. Once you did this, you need to change the ownership of the respective folder to 200:200.

See the example below:

$ ssh user@hostname

hostname $ mkdir -p /opt/nexus

hostname $ chown -R 200:200 /opt/nexus

External persistent volumes

{
  "service": {
    "name": "nexus",
    "cpus": 1,
    "mem": 2048,
    "role": "*",
    "local-volumes": {},
    "external-volumes": {
      "enabled": true
    }
  },
  "networking": {
    "virtual-host": "nexus.dcos.mydomain.mytld"
  }
}

The above options.json file configures Nexus 3 as follows:

• name: This parameter configures the name of the service itself.
• cpus: This parameter configures the number of CPU share to allocate to Nexus 3.
• mem: This parameter configures the amount of RAM to allocate to Nexus 3.
• role: The role which should be used to launch the service. Default is *.
• local-volumes: Can be left blank if using external persistent volumes.
• external-volumes: This parameter configures whether service should use external persistent volumes. If so, the following property need to be defined as well:
• enabled: Signals that external persistent volumes should be used.
• networking: Use this if you want your Nexus 3 service to be available externally.
• virtual-host: Specify the CNAME (or FQDN) of your edge loadbalancer of the DC/OS cluster to be used to expose the service on.

Usage

If you defined networking.virtual-host you should be able to access Nexus 3 on the URL you specified there. Otherwise, you can access it from inside the DC/OS via http://nexus.marathon.mesos:<hostPort>, where the hostPort can be found under the Nexus task's details under the Services tab of the DC/OS UI.

The initial username/password combination to log in is admin and admin123.

For further documentation on how to use Nexus 3, please refer to the docs.