rp.md

Resource Plugins

Resource plugin is an executable or script which generates RMS configuration for dds-submit. It can be written in any programming language and doesn’t depend on ODC.

The contract between resource plugin and ODC:

• Input: a resource description string. For example, it can be in JSON ar XML format or any other format. ODC executes plugin and provides a resource string via --res and partition ID via --id command line options:

myplugin --res "Resource description string" --id "Partition ID"

• Output: an RMS configuration in stdout in the XML format.

Resource description format

ODC uses XML with the following top level tags:

Tag	Description
<rms>	Name of the DDS RMS plugin
<configFile>	Path to the configuration file
<agents>	Number of agents
<slots>	Number of slots per agent

Each tag corresponds to the command line option used by dds-submit. Not all tags are required. A set of required tags depends on the used DDS RMS plugin.

Built-in plugins

ODC provides the odc-rp-same plugin out of the box. The plugin prints to stdout a received resource description string. It can be used, for example, if ODC client (or ECS) generates the RMS configuration itself.

ODC also implemens odc-rp-epn plugin for EPN project of ALICE. The plugin queries node allocation info via a special epnc service using gRPC and generates SSH configuration file for DDS. Plugin expects JSON resource description provided via --res option. Either a single resource or an array of resources can be requested:

{
   "zone":"online",
   "n":10
}

or

[{
   "zone":"online",
   "n":10
 },
 {
   "zone":"calib",
   "n":1
}]

zone is the zone name. n is the number of EPN nodes.

Register custom plugins

In order to use custom resource plugin one need to register it in ODC server. odc-grpc-server and odc-cli-server have --rp command line option which allows to register custom plugins. For example:

odc-grpc-server --rp my_plugin:/path/to/my_plugin another_plugin:/path/to/another_plugin

Registered plugins can be addressed by using plugin field of SubmitRequest or RunRequest.

Resource plugin examples

ODC containes several examples of resource plugins:

• A built-in odc-rp-same plugin implemented in C++.
• A built-in odc-rp-epn plugin uses gRPC and implemented in C++.
• A built-in odc-rp-epn-slurm Receives resources description from AliECS via gRPC and translates these into DDS slurm configuration.
• A DDS SSH configuration plugin implemented as a bash script.