Configuring Existing Clusters

ACTIVATE allows users to access the capabilities of an existing HPC cluster remotely.

Creating a Cluster Definition

Navigate to the Clusters page under the Compute tab.

Click the + Add button

Select Existing Cluster.

Enter a name for the cluster. The description is optional.

Click Create.

On the next page, click the edit (pencil) icon in the breadcrumb to open the cluster's Definition page.

If the existing cluster you wish to connect to utilizes a jump host, set Jump node to Yes. Enter the proper Jump node user and Jump node host information to continue.

In the Cluster config section, enter the Username, then add the login node under Cluster login nodes. Typically, the login Node refers to the IP address or host name of the cluster you wish to access. Your organization should have provided this information to you.

Click Save Changes.

Connecting to the Cluster

After configuring the cluster, go back to the cluster's Details page and click Connect.

Click Connection Logs to watch HPC Connect authenticate your connection.

If your organization uses multi-factor authentication, you will be prompted to enter a token. This may be an RSA token, YubiKey, or other type of token that’s specific to your organization.

This prompt will also appear if you use a passphrase protected key instead of the default workspace key.

If no token is required, you will be connected to the cluster immediately.

Once you're logged in to the cluster, you can run workflows as well as browse, edit, and upload files using the Editor.

Host Key Verification

If your administrator has turned on SSH host key verification, the first time you connect, you will need to confirm the ssh host key for the machine. Make sure this matches the host key for the machine you are connecting to.

ACTIVATE records the key you accept, and later connections must see the same key. Each login node is recorded separately, so you may be asked once for each login node.

If a host later presents a different key, HPC Connect tells you the key has changed and shows the new fingerprint next to the recorded one. A changed key usually means the host was reinstalled or its keys were replaced, but it can also mean someone is intercepting the connection. Confirm the new fingerprint with your HPC center before you accept it. Type yes to replace the recorded key, so the old key is no longer trusted. Any other answer stops the connection.

Only the cluster's owner is asked, and only when connecting from HPC Connect. Automatic connections, pw ssh and workflows refuse a changed key, and the connection logs show both fingerprints. Connect from HPC Connect to confirm the new key.

You can also clear the recorded keys yourself: open the cluster's actions menu, click Forget Host Keys, then confirm. Only the cluster's owner sees this option. The next connection shows the fingerprint and asks you to trust it. Clusters that connect with GSI (gsissh) aren't asked about a changed key, so use Forget Host Keys for them.

Disconnecting

After you've finished utilizing the cluster, click the power button in the Sessions tab. A dialog box will appear. Click Turn Off.

A notification will appear in the bottom right corner of your screen with the message Stopping [cluster name].

Configuring Settings

Typically when you create an existing cluster, you’ll be connecting to an on-premises cluster associated with your organization. However, the instructions here for existing clusters can be used with any pre-created Slurm cluster. The settings that are specific to this type of cluster are outlined below. If you’re unsure what to choose for these options, contact your organization’s ACTIVATE administrator.

General Settings

Auth method

Use this dropdown menu to select how ACTIVATE will connect to the existing cluster.

• User workspace (~/.ssh/pw_id_rsa): your user workspace logs in to the cluster over SSH with your workspace key, then starts the ACTIVATE agent on the login node under your cluster account. After that, terminals, sessions, and file transfers can travel over the agent's encrypted connection. For more information about the workspace key, see our documentation.
• PW CLI: use this when your workspace can't reach the cluster over SSH, for example when the cluster is on a private network. You run pw agent connect <cluster> on the cluster's login node yourself, and the agent connects out to ACTIVATE. The cluster page shows the exact command once you save.
• Proxy certificate server: your workspace logs in with a certificate issued by your organization's proxy certificate server.
• A saved SSH private key: any private keys you've added to your account also appear in this list. Your workspace logs in with that key instead of the workspace key.

Jump Node

Use this toggle button if you’re connecting to a cluster that has a jump node enabled. A jump node—also called a host node, bastion node, or login node—is a high-security server that allows a user to access a private machine or network.

If you enable this feature, two new fields will appear for Jump Node User and Jump Node Host. Your organization will have these credentials if you need them.

Cluster Configuration Settings

Username

Use this field to enter the username assigned to you for this cluster.

Cluster Login Node

Use this field to enter the IP address or host name of the cluster.

Scheduler Type

Use this dropdown menu to select the type of job scheduler the cluster uses. Currently, the Existing Cluster resource type supports Slurm and PBS.