This directory contains a simple example using structured configuration in the Component Framework.
If these components are not present in your build, they can be added by appending --with //examples to your fx set command. For example:
$ fx set core.x64 --with //examples --with //examples:tests $ fx build
Use ffx component run to launch the config_example component into a restricted realm for development purposes:
$ ffx component run /core/ffx-laboratory:config_example fuchsia-pkg://fuchsia.com/cpp_config_example#meta/config_example.cm
--recreate will delete the existing C++ component and replace it with the Rust component implementation.
$ ffx component run /core/ffx-laboratory:config_example fuchsia-pkg://fuchsia.com/rust_config_example#meta/config_example.cm --recreate
When the above commands are run, you can see the following output with fx log:
[04821.191151][508383][508385][ffx-laboratory:config_example] INFO: [main.cc(29)] Hello, World! (from C++) [04883.083137][514250][514252][ffx-laboratory:config_example] INFO: Hello, World! (from Rust)
Use ffx component show to see the configuration of this component:
$ ffx component show /core/ffx-laboratory:config_example Moniker: /core/ffx-laboratory:config_example URL: fuchsia-pkg://fuchsia.com/rust_config_example#meta/config_example.cm Instance ID: None Type: CML Component Component State: Resolved Incoming Capabilities: /svc/fuchsia.logger.LogSink Exposed Capabilities: diagnostics Merkle root: 20db03957098e49df4119ed9b96c7a7b181787868e830ac54e79ea538d220dfb Configuration: delay_ms -> Uint64(100) greeting -> String("World") Execution State: Running Start reason: Instance was started from debugging workflow Running since: 2023-01-31 22:16:14.599032884 UTC Job ID: 514225 Process ID: 514250 Outgoing Capabilities: diagnostics
These examples are able to accept overridden configuration values during development by adding to your fx set:
$ fx set core.x64 \ --with //examples/components/config \ --args='config_example_cpp_greeting="C++ CLI Override"' \ --args='config_example_rust_greeting="Rust CLI Override"' $ fx build
$ ffx component run /core/ffx-laboratory:config_example fuchsia-pkg://fuchsia.com/cpp_config_example#meta/config_example.cm --recreate
$ ffx component run /core/ffx-laboratory:config_example fuchsia-pkg://fuchsia.com/rust_config_example#meta/config_example.cm --recreate
In fx log:
[06524.333598][663879][663881][ffx-laboratory:config_example] INFO: [main.cc(29)] Hello, C++ CLI Override! (from C++) [06562.344829][667626][667628][ffx-laboratory:config_example] INFO: Hello, Rust CLI Override! (from Rust)
These examples also publish their configuration to an Inspect VMO.
$ ffx inspect show core/ffx-laboratory\*config_example core/ffx-laboratory\:config_example: metadata: filename = fuchsia.inspect.Tree component_url = fuchsia-pkg://fuchsia.com/rust_config_example#meta/config_example.cm timestamp = 6758159784100 payload: root: config: delay_ms = 100 greeting = Rust CLI Override
Integration tests for structured config are available in the integration_test directory. Use the ffx test run command to run the tests on a target device:
$ ffx test run fuchsia-pkg://fuchsia.com/cpp_config_integration_test#meta/config_integration_test_cpp.cm $ ffx test run fuchsia-pkg://fuchsia.com/rust_config_integration_test#meta/config_integration_test_rust.cm
You should see an integration test for each language execute and pass:
Running test 'fuchsia-pkg://fuchsia.com/cpp_config_integration_test#meta/config_integration_test_cpp.cm' [RUNNING] IntegrationTest.ConfigCpp [PASSED] IntegrationTest.ConfigCpp [RUNNING] IntegrationTest.ConfigCppReplaceSome [PASSED] IntegrationTest.ConfigCppReplaceSome [RUNNING] IntegrationTest.ConfigCppReplaceAll [PASSED] IntegrationTest.ConfigCppReplaceAll 3 out of 3 tests passed... fuchsia-pkg://fuchsia.com/cpp_config_integration_test#meta/config_integration_test_cpp.cm completed with result: PASSED ...
NOTE: This test will not pass if the configuration value is overridden.
Configuration values for a component can be specified using GN args or from a JSON file. To use packages that get values from a JSON file, append the _with_json_values to the package names used above.
$ ffx component run /core/ffx-laboratory:config_example fuchsia-pkg://fuchsia.com/cpp_config_example_with_json_values#meta/config_example.cm --recreate