In some environments, when attempting to install or configure a DSE cluster with OpsCenter Lifecycle Manager, it fails with the following error:
Meld failed on: name="east1" ssh-management-address="184.108.40.206" node-id="65005520-aa3d-4412-be2c-e35098d53e46" job-id="fe536440-12cc-46e8-8725-6aa8eb11dbd8" stdout="--callback-address is required
From the OpsCenter server you can SSH to the target node and see no output when you run 'echo $SSH_CLIENT'.
This can be worked around by setting the reported_interface option in the [agents] section of the opscenterd.conf file. This option should be set to an ip-address that targets can send http/https requests to.
Although Lifecycle Manager initiates and SSH connection FROM the OpsCenter server TO the target nodes, targets additionally issue API requests over http/https FROM the targets TO the OpsCenter server. Targets attempt to contact OpsCenter at their "callback-address". The callback-address is normally detected automatically by checking the SSH_CLIENT environment variable on the target node after logging in. In a small percentage of environments, the SSH_CLIENT envionment variable is unset and no address can be detected, resulting in the error noted above. The auto-detection process can be overridden by setting the reported_interface option, more information about this options is available at https://docs.datastax.com/en/opscenter/6.0/opsc/configure/opscConfigProps_r.html.
This issue is commonly encountered on the Rightscale targets frequently used by DataStax engineers to create test environments.