Observability
Inspecting from code
Every reference can report on its actor without disturbing it:
status(),msg_len(),signal_len()andreached_backpressure()read single values;snapshot()returns aChannelSnapshotwith the status, queue lengths, and the recent spawn and exit history.
A running tree can be walked with SupervisionTree. It starts from a
supervisor’s ChildDescription and asks each supervisor for its children with
GetChildren; see Dynamic addresses.
Any actor can take part in health reporting by accepting GetHealth and
replying with a Health: healthy, degraded or unhealthy, with an optional
message and details.
The HTTP API server
ApiServer is an actor that serves the tree over HTTP. Add it as a child next
to the rest of the tree, and give it the name of the root supervisor:
Supervisor::blueprint()
.child(ApiServer::blueprint("127.0.0.1:8080".parse()?, "root-supervisor").name("api-server")?)
.child(app_supervisor)
.name("root-supervisor")?| Route | Returns |
|---|---|
GET /processes | every actor in the tree, with its status and child configuration |
GET /snapshots | a ChannelSnapshot per name, or null if it is gone |
GET /health | a Health per name, or null if it is gone or didn’t answer in time |
The last two take a JSON array of names as the request body.
The routes are not stable yet and may change in any minor release.
The inspector
zestors-inspector is a desktop GUI, still a proof of concept, that draws the
tree served by the API server and polls it for changes. It connects to
http://localhost:8080.
cargo run -p zestors --example supervision # in one terminal
just inspector run # in another; or: cargo run --release -p zestors-inspector
The API server and the inspector see one process. In a cluster, each node runs its own.