RFC-0146：CML 中的结构化配置架构

{
    use: {
        ...,
    },
    ...
    config: {
        <key>: {
            type: "<type string>",
            <additional properties based on type>
        },
        ...
    }
}

config: {
    enable_advanced_features: { type: "bool" },
    num_threads: { type: "uint64" },
}

config: {
    network_id: {
        type: "string",
        max_size: 100,
    }
}

config: {
    tags: {
        type: "vector",
        max_count: 10,
        element: {
            type: "string",
            max_size: 20,
        }
    }
}

config: {
    // proxy the kernel logger
    enable_klog: { type: "bool" },

    // initializes syslog library with a log socket to itself
    consume_own_logs: { type: "bool" },

    // connects to the component event provider. This can be set to false when the
    // archivist won't consume events from the Component Framework v1 to remove log spam.
    enable_component_event_provider: { type: "bool" },

    ...

    // initializes logging to debuglog via fuchsia.boot.WriteOnlyLog
    log_to_debuglog: { type: "bool" },

    // number of threads the archivist has available to use.
    num_threads: { type: "uint32" }
}

program: {
    ...
    args: [
         // The mode is passed over argv because it does not vary for this component manifest.
         // Launcher will use the mode to determine the program to run.
         "detect"
    ]
},
config: {
    // how often to scan Diagnostic data
    // unit: minutes
    //
    // NOTE: in detect's CLI parsing, this is optional with a default specified in code.
    // when using structured config, the default would be provided by a build template or
    // by product assembly.
    check_every: { type: "uint64" },

    // if true, minimum times will be ignored for testing purposes.
    // never check in code with this flag enabled.
    test_only: { type: "bool" },
}

config: {
    // Add a tag to the allow list. Log entries with matching tags will be output to
    // the console. If no tags are specified, all log entries will be printed.
    allowed_log_tags: {
        type: "vector",
        max_count: 40,
        element: {
            type: "string",
            max_size: 40,
        }
    },

    // Add a tag to the deny list. Log entries with matching tags will be prevented
    // from being output to the console. This takes precedence over the allow list.
    denied_log_tags: {
        type: "vector",
        max_count: 40,
        element: {
            type: "string",
            max_size: 40,
        }
    },
}

library fuchsia.component.decl;

// Config keys can only consist of these many bytes
const CONFIG_KEY_MAX_SIZE uint32 = 64;

// The string identifier for a config field.
alias ConfigKey = string:CONFIG_KEY_MAX_SIZE;

// The checksum produced for a configuration interface.
// Two configuration interfaces are the same if their checksums are the same.
type ConfigChecksum = flexible union {
    // A SHA-256 hash produced over a component's config interface.
    1: sha256 array<uint8>:32
};

/// The schema of a component's configuration interface.
type ConfigSchema = table {
    // Ordered fields of the component's configuration interface.
    1: fields vector<ConfigField>:MAX;

    // Checksum produced over a component's configuration interface.
    2: checksum ConfigChecksum;
};

// Declares a single config field (key + type)
type ConfigField = table {
    // The identifier for this config field.
    // This key will be used to match overrides.
    1: key ConfigKey;

    // The type of config values. Config values are verified
    // against this layout at build time and run time.
    2: type ConfigType;
};

// The type of a config value
type ConfigType = struct {
    layout ConfigTypeLayout;
    parameters vector<LayoutParameter>;
    constraints vector<LayoutConstraint>;
};

// Defines valid type ids for config fields.
type ConfigTypeLayout = flexible enum {
    BOOL = 1;
    UINT8 = 2;
    UINT16 = 3;
    UINT32 = 4;
    UINT64 = 5;
    INT8 = 6;
    INT16 = 7;
    INT32 = 8;
    INT64 = 9;
    STRING = 10;
    VECTOR = 11;
};

// Parameters of a given type layout
type LayoutParameter = table {
    // For vectors, this is the type of the nested element.
    1: nested_type ConfigType;
};

// Constraints on a given type layout
type LayoutConstraint = table {
    // For strings, this is the maximum number of bytes allowed.
    // For vectors, this is the maximum number of elements allowed.
    1: max_size uint32;
};

// *** component.fidl ***

library fuchsia.component.decl;
// NOTE: as long as the two libraries are supported, this change will also be made to
// library fuchsia.sys2;

/// A component declaration.
///
/// This information is typically encoded in the component manifest (.cm file)
/// if it has one or may be generated at runtime by a component resolver for
/// those that don't.
type Component = table {
    /// ... previous fields ...

    /// The schema of a component's configuration interface.
    10: config ConfigSchema;
};

$ ffx component show netstack
Moniker: /core/network/netstack
URL: fuchsia-pkg://fuchsia.com/network#meta/netstack.cm
Type: CML static component
Component State: Resolved
...
Configuration:
  log_packets [bool]
  verbosity [string:10]
  socket_stats_sampling_interval [uint32]
  opaque_iids [bool]
  tags [vector<string:10>:20]
Execution State: Running
...

program: {
    config: {
        <key>: {
            type: "<type string>",
            <additional JSON fields based on type>
        },
    }
}

config: {
    fields: {
        <key>: {
            type: "<type string>",
        }
        ...
    }
}

config: [
    {
        key: "<key>",
        type: "<type string>",
    }
    ...
]

config: {
    <key>: "<type string>"
    ...
}

config: [
    {
        <type string>: "<key>",
        ...
    },
],

config: {
    enable_advanced_features: {
        type: "bool",
        default: false,
    }
    tags: {
        type: "vector",
        max_count: 10,
        element: {
            type: "string",
            max_size: 20,
        }
        default: [
            "foo",
            "bar",
            "baz",
        ]
    }
}

config: {
    fsck: {
        type: "struct",
        fields: {
            check_on_mount: { type: "bool" },
            verify_hard_links: { type: "bool" },
            repair_errors: { type: "bool" },
        }
    },
    compression_type: {
        type: "enum",
        variants: {
            uncompressed: 0,
            zstd_chunked: 1,
        }
    },
    // Vectors can store complex structures
    coordinates: {
        type: "vector",
        max_count: 10,
        element: {
            type: "struct",
            fields: {
                x: { type: "int32" },
                y: { type: "int32" },
            }
        }
    },
}

config: {
      /// Add a tag to the allow list. Log entries with matching tags will be output to
      /// the console. If no tags are specified, all log entries will be printed.
      allowed_log_tags: {
          type: "vector",
          max_count: 40,
          element: {
              type: "string",
              max_size: 40,
          }
      },

      /// Add a tag to the deny list. Log entries with matching tags will be prevented
      /// from being output to the console. This takes precedence over the allow list.
      denied_log_tags: {
          type: "vector",
          max_count: 40,
          element: {
              type: "string",
              max_size: 40,
          }
      },
}

config: {
    network_id: {
        type: "string",
        max_size: "MAX",
    }
}

config: {
    tags: {
        type: "vector",
        element: {
            type: "string"
        }
    }
}