Bug #6156
Updated by Tom Clegg almost 10 years ago
h2. Goals
Have the process documented in our "compute node install guide":http://doc.arvados.org/install/install-compute-node.html work out of the box. Right now this doesn't work because when the node first pings the API server, #ping assigns a slot_number for the node, then overwrites the hostname based on that.
We can't just have the sysadmin assign a slot_number in the install process, because it needs to be unique and it's hard to figure out a general way to accommodate that constraint.
h2. Implementation
* Introduce a configuration variable to API server @assign_node_hostname@ that can be a format string (similar to the dns configs) to generate a compute node hostname given a slot_number. It can also be set to false if the API server is not expected to generate hostnames.
* Update Node.hostname_for_slot to return a result based on the configured format string, or nil if the setting is unset.
* In Node#ping, assign a hostname if hostname is nil and @assign_node_hostname@ is set. Move this code outside the @if self.slot_number.nil?@ block, below it—each value can be set independently when it's not included in the existing record.
* Only run the Node DNS checking code (below hostname_for_slot) when @assign_node_hostname@ is set.
In application.default.yml
* <pre>
# Hostname to assign to a compute node when it sends a "ping" and the
# hostname in its Node record is nil.
# During bootstrapping, the "ping" script is expected to notice the
# hostname given in the ping response, and update its unix hostname
# accordingly.
# If false, leave the hostname alone (this is appropriate if your compute
# nodes' hostnames are already assigned by some other mechanism).
#
# One way or another, the hostnames of your node records should agree
# with your DNS records and your /etc/slurm-llnl/slurm.conf files.
#
# Example for compute0000, compute0001, ....: "compute%<slot_number>04d"
# (See http://ruby-doc.org/core-2.2.2/Kernel.html#method-i-format for more.)
assign_node_hostname: "compute{slot_number}"
</pre>