I want filter log by target.

[SamPeng87]

The behavior does not match my expectations when using default settings compared to filtering only by target. By default, span information is included, but when filtering by target, the span information is missing. I am using actix-web, and this span is automatically added by TracingLog. I can't understand why this happens. My expectation is that filtering by target, or filtering by any criteria, should retain all information just like when no filtering is applied.

If I use default filter

like that

    let filter = filter::Targets::new().with_default(level_filter);
    print("{:?}",filter)
    let app_json_layer = FmtLayer::new()
        .json()
        .with_writer(app_file_appender)
        .with_filter(filter);

output

Targets(DirectiveSet { directives: [StaticDirective { target: None, field_names: [], level: LevelFilter::DEBUG }], max_level: LevelFilter::DEBUG })

log file output:

{
  "timestamp": "2024-11-01T11:22:41.987623Z",
  "level": "INFO",
  "fields": {
    "message": "Getting feed..",
    "log.target": "server::api::v1::feeds::get",
    "log.module_path": "server::api::v1::feeds::get",
    "log.file": "server/src/api/v1/feeds/get.rs",
    "log.line": 44
  },
  "target": "server::api::v1::feeds::get",
  "span": {
    "http.client_ip": "127.0.0.1",
    "http.flavor": "1.1",
    "http.host": "localhost:8080",
    "http.method": "GET",
    "http.route": "/api/v1/feeds/{id}",
    "http.scheme": "http",
    "http.target": "/api/v1/feeds/d448f2ba-5ef0-4567-87ce-f14f929513e5",
    "http.user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36",
    "otel.kind": "server",
    "otel.name": "GET /api/v1/feeds/{id}",
    "request_id": "2af89e85-2593-4e01-ba87-1260f9ac1098",
    "name": "HTTP request"
  },
  "spans": [
    {
      "http.client_ip": "127.0.0.1",
      "http.flavor": "1.1",
      "http.host": "localhost:8080",
      "http.method": "GET",
      "http.route": "/api/v1/feeds/{id}",
      "http.scheme": "http",
      "http.target": "/api/v1/feeds/d448f2ba-5ef0-4567-87ce-f14f929513e5",
      "http.user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36",
      "otel.kind": "server",
      "otel.name": "GET /api/v1/feeds/{id}",
      "request_id": "2af89e85-2593-4e01-ba87-1260f9ac1098",
      "name": "HTTP request"
    }
  ]
}

but,if i use filter by target

    let filter = filter::Targets::new().with_target("server",level_filter);
    println!("{:?}", filter);
    let app_json_layer = FmtLayer::new()
        .json()
        .with_writer(app_file_appender)
        .with_filter(filter);

output

Targets(DirectiveSet { directives: [StaticDirective { target: Some("server"), field_names: [], level: LevelFilter::DEBUG }], max_level: LevelFilter::DEBUG })

log file

{
  "timestamp": "2024-11-01T11:51:58.232915Z",
  "level": "INFO",
  "fields": {
    "message": "Getting feed..",
    "log.target": "server::api::v1::feeds::get",
    "log.module_path": "server::api::v1::feeds::get",
    "log.file": "server/src/api/v1/feeds/get.rs",
    "log.line": 44
  },
  "target": "server::api::v1::feeds::get"
}

What's wrong with my use？