Whenever we run a BDA upgrade we see as one of the prerequisites checks, to have the httpd service up and running on the first node of the cluster
- The httpd service must be started on Node 1 of the cluster. It should be stopped on all other nodes.
This is only needed during cluster upgrade or reconfiguration, but it is recommended to have it running at all times.
The reason for that is because we will run yum from every node in the cluster pointing to the repository that is created on node 1 when we deploy the bundle with the new release.
On /etc/yum.repos.d/bda.repo we can see that baseurl is using the first node and http protocol:
The repository is used on the event of upgrades and patching, and during these operation the httpd service must be up on node 1 of the cluster.
During normal operation, whenever upgrades or patching is not being run, the http service can be brought down if desired.
MOS Upgrade documents