Health check is a standardized inspection metric. Adding a fuchsia.inspect.Health child to an Inspect Node gives that node the contained health information. This information can be aggregated by system-wide health-checking tools.
The layout of the health check node
The following properties and metrics are exported in any health check node:
| Name | Type | Description |
|---|---|---|
start_timestamp_nanos | int64 | The monotonic clock system timestamp at which this health node was initialized (i.e. first became STARTING UP) |
message | String | If status==UNHEALTHY, this includes an optional failure detail message. |
status | Enum | STARTING_UP:The health node was initialized but not yet marked running. |
OK:The subsystem reporting to this health node is reporting healthy. | ||
UNHEALTHY:The subsystem reporting to this health node is reporting unhealthy. |
User guide
The following example illustrates the use of ffx inspect for getting information about the component health status.
Examples:
$ ffx inspect show core/a: root: fuchsia.inspect.Health: start_timestamp_nanos = ... status = OK connections: 0: fuchsia.inspect.Health: start_timestamp_nanos = ... status = STARTING_UP optional_database: fuchsia.inspect.Health: start_timestamp_nanos = ... status = UNHEALTHY message = "Cannot open local.file" core/a: root: fuchsia.inspect.Health: start_timestamp_nanos = ... status = OK core/a: root: fuchsia.inspect.Health: start_timestamp_nanos = ... status = UNHEALTHY message = "Failed to connect to fuchsia.example.RequiredService" $ ffx inspect show a.cm:root/fuchsia.inspect.Health:status b.cm:root/fuchsia.inspect.Healh:status c.cm:root/fuchsia.inspect.Health:status a: root: fuchsia.inspectHealth: status = OK b: root: fuchsia.inspectHealth: status = OK c: root: fuchsia.inspectHealth: status = UNHEALTHY Using health checks in components
The following sections explain how to use the library in Fuchsia components written in various programming languages.
C++
#include <lib/async-loop/cpp/loop.h> #include <lib/async-loop/default.h> #include <lib/sys/cpp/component_context.h> #include <lib/inspect/component/cpp/component.h> int main(int argc, char** argv) { async::Loop loop(&kAsyncLoopConfigAttachToCurrentThread); auto context = sys::ComponentContext::CreateAndServeOutgoingDirectory(); inspect::ComponentInspector inspector(loop.dispatcher(), inspect::PublishOptions{}); inspector.Health().StartingUp(); // ...Do startup work... inspector.Health().Ok(); inspector.Health().Unhealthy("I'm not feeling well."); inspector.Health().Ok(); loop.Run(); return 0; } Rust
use fuchsia_inspect as inspect; use fuchsia_inspect::health; fn main() { // If you have your own inspector, it's also possible to export its health. /* inspector needs to be initialized */ let inspector = /* ... */ let mut node = inspector::root(); let mut health = fuchsia_inspect::health::Node(node); // ... health.set_ok(); health.set_unhealthy("I'm not feeling well."); health.set_ok(); // The component is healthy again. }