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orchestrator.md

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EDGELESS orchestrator (ε-ORC)
Executable name edgeless_orc_d
Default conf file name orchestrator.toml

The ε-ORC is the component that manages an EDGELESS orchestration domain. It has the following main responsibilities:

  1. Domain formation: it offers a NodeRegistration API through which nodes may register and notify their (static) capabilities and (dynamic) system information metrics. The nodes refresh periodically their registration with the ε-ORC, also indicating a deadline by which a lack of refresh should be considered as a failure.
  2. Domain orchestration: the ε-CON assigns to the ε-ORC function and resource instances, which it is then responsible for handling at best within the nodes in its domain.
  3. Proxy maintenance: the ε-ORC may optionally synchronize its internal data structures and performance metrics with an external database via a Proxy. The database can then be queried by third-party services for monitoring purposes or to implement the delegated orchestrator concept.

The ε-ORC subscribes to its ε-CON via the DomainRegistration API, periodically refreshing the subscription (the period is configurable in the configuration file). When an ε-ORC first enters a cluster, its functions and resources are reset.

The ε-ORC has the following interfaces, also illustrated in the diagram below:

Interface Configuration file URL
FunctionInstance orchestrator_url
ResourceConfiguration orchestrator_url
NodeRegistration node_register_url

Proxy

When used, the ε-ORC mirrors its internal data structures on the proxy.

Currently, we only support Redis, which is enabled by means of the following section in orchestrator.toml:

[proxy]
proxy_type = "Redis"
redis_url = "redis://127.0.0.1:6379"

The Redis database is flushed automatically by the ε-ORC when it starts.

We provide a command-line interface, called proxy_cli, which can be used as a convenient alternative to reading directly from the Redis database.

Schema

Key Value Data type
domain_info:domain_id Identifier of the domain managed by this ε-ORC String
nodes:capabilities:node_id JSON object representing the capabilities of the node with given node identifier NodeCapabilities
node:health:node_id JSON object representing the health status of the node with given node identifier NodeHealthStatus
performance:function_execution_time:pid List of function execution times of the function with the given Physical Identifier, in fractional seconds, each associated with a timestamp with a millisecond resolution taken by the ε-ORC (format exec_time,timestamp) NodePerformanceSamples
provider:provider_id JSON object representing the configuration of the resource provider with given identifier ResourceProvider
instance:lid JSON object including the annotations of the function with given Logical identifier and the currently active instances (each with node identifier and physical function identifier) ActiveInstance
dependency:lid JSON object representing the dependencies of the function with given Logical identifier through a map of output channel names to logical function identifiers HashMap<Uuid, HashMap<String, Uuid>>

The following identifiers are represented in UUID format:

  • node's identifier (node_id)
  • logical function/resource instance identifier (lid)
  • physical function/resource instance identifier (pid)

The following identifiers are represented as free-text strings:

  • domain identifier
  • provider identifier