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Component runners extend the component framework through an environment to provide a runtime for launching new component instances.
Component manager launches components by sending a request containing ComponentStartInfo
to the appropriate runner using the fuchsia.component.runner.ComponentRunner
protocol. The ComponentStartInfo
contains details about the component‘s executable and its namespace. The runner manages the component’s execution within the supported runtime.
After starting the component, component manager uses the fuchsia.component.runner.ComponentController
protocol provided in the Start
request to send execution actions to the runner, such as stopping the component. The runner chooses how to interpret these commands as appropriate to the component runtime.
To provide a runner capability, a component must declare a runner
capability, whose path
designates a FIDL protocol implementing fuchsia.component.runner.ComponentRunner
served from the component's outgoing directory.
{ capabilities: [ { runner: "web", path: "/svc/fuchsia.component.runner.ComponentRunner", }, ], }
Component manager sends ComponentRunner/Start
requests to this protocol. Each request includes a ComponentController
channel which the runner should serve to handle lifecycle events for the component.
Components route runner capabilities by exposing them to their parent and offering them to their children.
For more details on how the framework routes component capabilities, see capability routing.
Exposing a runner capability gives the component's parent access to that capability:
{ expose: [ { runner: "web", from: "self", }, ], }
You may optionally specify:
Offering a runner capability gives a child component access to that capability:
{ offer: [ { runner: "web", from: "self", to: [ "#child-a" ], }, ], }
You may optionally specify:
Component runners are made available to components through their environment. To register a new runner within an environment, add a new entry to the runners
section of the environments
declaration:
environments: [ { name: "my-environ", extends: "realm", runners: [ { runner: "web", from: "parent", }, ], }, ]
You may optionally specify:
For more details on how to apply environments to components, see the environments documentation.
A component specifies the appropriate runner for execution using the program
section of its manifest. The program
section designates the runner
as well as any runner-specific options. The runner must be registered in the component's environment.
For example, a component which runs as a web page might have a program
like the following:
program: { runner: "web", mode: "incognito", },
When the component manager attempts to launch this component, it will send a request to the provider of the web
runner to start it.
You may expose
, offer
, or register the runner capability under a different name using the as
parameter:
{ expose: [ { runner: "web", from: "#chromium", as: "web-chromium", }, ], }
Component framework provides the following built-in component runners:
{ program: { runner: "elf", binary: "bin/example", }, }