flexi_logger 0.31.8

An easy-to-configure and flexible logger that writes logs to stderr or stdout and/or to files. It allows custom logline formats, and it allows changing the log specification at runtime. It also allows defining additional log streams, e.g. for alert or security messages.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

mod test_utils;

#[cfg(feature = "trc")]
mod a {
    use flexi_logger::{
        trc::FormatConfig, writers::FileLogWriter, Age, Cleanup, Criterion, FileSpec,
        LogSpecification, Naming, WriteMode,
    };
    use std::io::Write;
    use tracing::{debug, error, info, trace, warn};

    const WAIT_MILLIS: u64 = 1_500;

    #[test]
    fn test_specfile() {
        let specfile = super::test_utils::file("logspec.toml");

        std::fs::remove_file(&specfile).ok();
        assert!(!specfile.exists());

        let keep_alive_handles = flexi_logger::trc::setup_tracing(
            LogSpecification::info(),
            Some(&specfile),
            FileLogWriter::builder(FileSpec::default().directory(super::test_utils::dir()))
                .rotate(
                    Criterion::Age(Age::Day),
                    Naming::Timestamps,
                    Cleanup::KeepLogFiles(7),
                )
                .write_mode(WriteMode::Async),
            &FormatConfig::default()
                .with_ansi(false)
                .with_level(true)
                .with_target(true)
                .with_time(true),
        )
        .unwrap();

        assert!(specfile.exists());

        write_logs(0);
        super::b::write_logs(0);

        eprintln!(
            "[{}] ===== behave like many editors: rename and recreate; set to warn",
            super::test_utils::now_local()
        );
        {
            let mut old_name = specfile.clone();
            old_name.set_file_name("old_logspec.toml");
            std::fs::rename(&specfile, old_name).unwrap();
            let mut file = std::fs::OpenOptions::new()
                .create(true)
                .append(true)
                .open(&specfile)
                .unwrap();
            file.write_all(
                b"
                global_level = 'warn'\n\
                [modules]\n\
                'test_trc::b' = 'error'\n\
                ",
            )
            .unwrap();
        }

        std::thread::sleep(std::time::Duration::from_millis(WAIT_MILLIS));

        write_logs(1);
        super::b::write_logs(1);

        eprintln!(
            "[{}] ===== truncate and rewrite; set to error",
            super::test_utils::now_local()
        );
        {
            let mut file = std::fs::OpenOptions::new()
                .truncate(true)
                .write(true)
                .open(&specfile)
                .unwrap();
            file.write_all(
                "\
                global_level = 'error'\n\
                [modules]\n\
                'test_trc::b' = 'debug'\n\
                "
                .as_bytes(),
            )
            .unwrap();
        }

        std::thread::sleep(std::time::Duration::from_millis(WAIT_MILLIS));

        write_logs(2);
        super::b::write_logs(2);

        std::thread::sleep(std::time::Duration::from_millis(WAIT_MILLIS));

        keep_alive_handles.0.validate_logs(&[
            ("ERROR", "test_trc::a", "0"),
            ("WARN", "test_trc::a", "0"),
            ("INFO", "test_trc::a", "0"),
            ("ERROR", "test_trc::b", "0"),
            ("WARN", "test_trc::b", "0"),
            ("INFO", "test_trc::b", "0"),
            ("ERROR", "test_trc::a:", "1"),
            ("WARN", "test_trc::a:", "1"),
            ("ERROR", "test_trc::b:", "1"),
            ("ERROR", "test_trc::a:", "2"),
            ("ERROR", "test_trc::b:", "2"),
            ("WARN", "test_trc::b:", "2"),
            ("INFO", "test_trc::b:", "2"),
            ("DEBUG", "test_trc::b:", "2"),
        ]);
    }

    pub(crate) fn write_logs(idx: u8) {
        error!("Error from a::write_logs {idx}");
        warn!("Warning from a::write_logs {idx}");
        info!("Info from a::write_logs {idx}");
        debug!("Debug from a::write_logs {idx}");
        trace!("Trace from a::write_logs {idx}");
    }
}
mod b {
    use tracing::{debug, error, info, trace, warn};

    pub(crate) fn write_logs(idx: u8) {
        error!("Error from b::write_logs {idx}");
        warn!("Warning from b::write_logs {idx}");
        info!("Info from b::write_logs {idx}");
        debug!("Debug from b::write_logs {idx}");
        trace!("Trace from b::write_logs {idx}");
    }
}