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Hostnames and Routing

Before you start

Goal

  • Ensure Hostnames are correct and a server and worker may communicate correctly.

Prerequisites

  • A configured Altair SLC Hub server.
  • A configured worker node.
  • Administration privileges for the server host and worker node if running Windows.

Altair SLC Hub server preparation

Before installing software on the Altair SLC Hub worker nodes, some configuration is required on the main Altair SLC Hub server host.

The host name for the main Altair SLC Hub server used in HTTPS certificates for internal Altair SLC Hub communications is specified in the casvc.hostname configuration property. By default this will be set to the main Altair SLC Hub ingress hostname. Review this setting using the command:

hubctl config print casvc.hostname

The default value for this configuration setting is in the Altair SLC Hub configuration file [etc directory]/config.d/casvc.yaml.

If Altair SLC Hub worker nodes are not able to communicate with the main Altair SLC Hub server using that host name, the host name can be changed to a more appropriate one.

Do not edit the installation-supplied configuration files directly. Instead, create a new file in the same directory with a lexicographically greater name such as casvc_hostname.yaml and use that to override the configuration setting.

For example, to use the host name "mainhub" create a file called casvc_hostname.yaml and set the contents to: 

casvc:
  hostname: mainhub

If the host name is changed and the Altair SLC Hub CA service is installed, it is necessary to restart the Altair SLC Hub CA service:

hubctl service restart casvc

Worker registration preparation

Having installed the Altair SLC Hub worker node software, the worker needs to be registered with Altair SLC Hub. Before this process can be performed it is necessary to verify that the correct hostname will be used during the registration. The value of the casvc.hostname configuration property on the worker node needs to be the fully-qualified hostname by which the Altair SLC Hub server can contact the worker node. An initial value of this configuration property is set during the installation process. The value can be viewed using the following command (run on the worker node):

hubctl config print casvc.hostname

The default value for this configuration setting is in the Altair SLC Hub configuration file [etc directory]/config.d/casvc.yaml file. If the main Altair SLC Hub server host is not able to communicate with the Altair SLC Hub worker node using that host name, the host name can be changed to a more appropriate one.

Do not edit the installation-supplied configuration files directly. Instead, create a new file in the same directory, with a lexicographically greater name such as casvc_hostname.yaml and use that to override the configuration setting.

For example, to use the host name "hubworker" create a file called [etc directory]/config.d/casvc_hostname.yaml and set the contents to: 

casvc:
  hostname: hubworker

There is nothing to restart on a worker node when this is done. The change will be detected when the hubctl worker register command is executed.

Verification

Altair SLC Hub comes with a utility that can be used to verify the network communication between the Altair SLC Hub host and the worker host, and to identify any firewall issues or other network routing issues that might exist.

First, ensure the Altair SLC Hub services are not active by running the following command on the worker node: 

hubctl service stop

You will need to know the hostname of the worker node. On the worker node, to find this out, run: 

hubctl config print internalnetwork.hostname

Next, run the following command on the worker node host:

hubctl portcheck worker

This command will start and then wait for communication. Once the test has completed successfully it will exit automatically.

Then run the following command on the Altair SLC Hub server host: 

hubctl portcheck server <worker-host-name>

Where <worker-host-name> is the host name of the worker node.

The command run on the Altair SLC Hub server host will perform various tests of communication between the Altair SLC Hub server and the worker node.

Once the test is complete, you can now start the slchub.nomad service on the worker node by running: 

hubctl service start nomad