Struct Env

Source

pub struct Env<'a> { /* private fields */ }

Expand description

Set of environment variables to configure from.

§Default environment variables

By default, the Env will read the following environment variables:

RUST_LOG: the level filter
RUST_LOG_STYLE: whether or not to print styles with records.

These sources can be configured using the builder methods on Env.

Implementations§

Source §

impl<'a> Env<'a>

Source

pub fn new() -> Self

Get a default set of environment variables.

Source

pub fn filter<E>(self, filter_env: E) -> Self
where E: Into<Cow<'a, str>>,

Specify an environment variable to read the filter from.

Examples found in repository ?

examples/custom_default_format.rs (line 26)

24fn init_logger() {
25    let env = Env::default()
26        .filter("MY_LOG_LEVEL")
27        .write_style("MY_LOG_STYLE");
28
29    Builder::from_env(env)
30        .format_level(false)
31        .format_timestamp_nanos()
32        .init();
33}

More examples

Hide additional examples

examples/custom_format.rs (line 28)

26    fn init_logger() {
27        let env = Env::default()
28            .filter("MY_LOG_LEVEL")
29            .write_style("MY_LOG_STYLE");
30
31        Builder::from_env(env)
32            .format(|buf, record| {
33                // We are reusing `anstyle` but there are `anstyle-*` crates to adapt it to your
34                // preferred styling crate.
35                let warn_style = buf.default_level_style(log::Level::Warn);
36                let timestamp = buf.timestamp();
37
38                writeln!(
39                    buf,
40                    "My formatted log ({timestamp}): {warn_style}{}{warn_style:#}",
41                    record.args()
42                )
43            })
44            .init();
45    }

Source

pub fn filter_or<E, V>(self, filter_env: E, default: V) -> Self
where E: Into<Cow<'a, str>>, V: Into<Cow<'a, str>>,

Specify an environment variable to read the filter from.

If the variable is not set, the default value will be used.

Examples found in repository ?

examples/default.rs (line 27)

22fn main() {
23    // The `Env` lets us tweak what the environment
24    // variables to read are and what the default
25    // value is if they're missing
26    let env = Env::default()
27        .filter_or("MY_LOG_LEVEL", "trace")
28        .write_style_or("MY_LOG_STYLE", "always");
29
30    env_logger::init_from_env(env);
31
32    trace!("some trace log");
33    debug!("some debug log");
34    info!("some information log");
35    warn!("some warning log");
36    error!("some error log");
37}

Source

pub fn default_filter_or<V>(self, default: V) -> Self
where V: Into<Cow<'a, str>>,

Use the default environment variable to read the filter from.

If the variable is not set, the default value will be used.

Source

pub fn write_style<E>(self, write_style_env: E) -> Self
where E: Into<Cow<'a, str>>,

Specify an environment variable to read the style from.

Examples found in repository ?

examples/custom_default_format.rs (line 27)

24fn init_logger() {
25    let env = Env::default()
26        .filter("MY_LOG_LEVEL")
27        .write_style("MY_LOG_STYLE");
28
29    Builder::from_env(env)
30        .format_level(false)
31        .format_timestamp_nanos()
32        .init();
33}

More examples

Hide additional examples

examples/custom_format.rs (line 29)

26    fn init_logger() {
27        let env = Env::default()
28            .filter("MY_LOG_LEVEL")
29            .write_style("MY_LOG_STYLE");
30
31        Builder::from_env(env)
32            .format(|buf, record| {
33                // We are reusing `anstyle` but there are `anstyle-*` crates to adapt it to your
34                // preferred styling crate.
35                let warn_style = buf.default_level_style(log::Level::Warn);
36                let timestamp = buf.timestamp();
37
38                writeln!(
39                    buf,
40                    "My formatted log ({timestamp}): {warn_style}{}{warn_style:#}",
41                    record.args()
42                )
43            })
44            .init();
45    }

Source

pub fn write_style_or<E, V>(self, write_style_env: E, default: V) -> Self
where E: Into<Cow<'a, str>>, V: Into<Cow<'a, str>>,

Specify an environment variable to read the style from.

If the variable is not set, the default value will be used.

Examples found in repository ?

examples/default.rs (line 28)

22fn main() {
23    // The `Env` lets us tweak what the environment
24    // variables to read are and what the default
25    // value is if they're missing
26    let env = Env::default()
27        .filter_or("MY_LOG_LEVEL", "trace")
28        .write_style_or("MY_LOG_STYLE", "always");
29
30    env_logger::init_from_env(env);
31
32    trace!("some trace log");
33    debug!("some debug log");
34    info!("some information log");
35    warn!("some warning log");
36    error!("some error log");
37}