feat(stdlib): Add get_vector_timezone function (#671)

* Add get_timezone_name to VRL stdlib

This function returns the name of the VRL timezone, or if
TimeZone::Local then it will attempt to get the timezone name from the
host OS. If that fails, then it will get the local time, and return the
formatted timezone offset (e.g., "+02:00")

Note that iana-time-zone was previously an indirect dependency, now it's
a direct dependency.

* Rename changelog.d fragment now that PR # is known

Cargo.toml

@@ -74,6 +74,7 @@ exitcode = {version = "1", optional = true }
 flate2 = { version = "1.0.28", default-features = false, features = ["default"], optional = true }
 hex = { version = "0.4", optional = true }
 hmac = { version = "0.12.1", optional = true }
+iana-time-zone = "0.1.59"
 indexmap = { version = "~2.2.2", default-features = false, features = ["std"], optional = true}
 indoc = {version = "2.0.4", optional = true }
 itertools = { version = "0.12.1", default-features = false, optional = true }

LICENSE-3rdparty.csv

@@ -207,7 +207,16 @@ web-sys,https://github.com/rustwasm/wasm-bindgen/tree/master/crates/web-sys,MIT
 webbrowser,https://github.com/amodm/webbrowser-rs,MIT OR Apache-2.0,Amod Malviya @amodm
 winapi,https://github.com/retep998/winapi-rs,MIT OR Apache-2.0,Peter Atashian <retep998@gmail.com>
 winapi-util,https://github.com/BurntSushi/winapi-util,Unlicense OR MIT,Andrew Gallant <jamslam@gmail.com>
-windows,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows-core,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows-sys,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows-targets,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows_aarch64_gnullvm,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows_aarch64_msvc,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows_i686_gnu,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows_i686_msvc,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows_x86_64_gnu,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows_x86_64_gnullvm,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
+windows_x86_64_msvc,https://github.com/microsoft/windows-rs,MIT OR Apache-2.0,Microsoft
 winnow,https://github.com/winnow-rs/winnow,MIT,The winnow Authors
 woothee,https://github.com/woothee/woothee-rust,Apache-2.0,hhatto <hhatto.jp@gmail.com>
 wyz,https://github.com/myrrlyn/wyz,MIT,myrrlyn <self@myrrlyn.dev>

benches/stdlib.rs

@@ -49,6 +49,7 @@ criterion_group!(
               get,
               get_env_var,
               get_hostname,
+              get_timezone_name,
               includes,
               int,
               ip_aton,
@@ -578,6 +579,15 @@ bench_function! {
     }
 }
 
+bench_function! {
+    get_timezone_name => vrl::stdlib::GetTimezoneName;
+
+    get {
+        args: func_args![],
+        want: Ok(vrl::stdlib::get_name_for_timezone(&vrl::compiler::TimeZone::Named(chrono_tz::Tz::UTC))),
+    }
+}
+
 bench_function! {
     includes => vrl::stdlib::Includes;
 

changelog.d/671.enhancement.md

@@ -0,0 +1,3 @@
+Add VRL function `get_timezone_name` to return the configured/resolved IANA timezone name.
+
+authors: klondikedragon

src/stdlib/get_timezone_name.rs

@@ -0,0 +1,74 @@
+use crate::compiler::prelude::*;
+use chrono::Local;
+use std::borrow::Cow;
+
+#[must_use]
+pub fn get_name_for_timezone(tz: &TimeZone) -> Cow<'_, str> {
+    match tz {
+        TimeZone::Named(tz) => tz.name().into(),
+        TimeZone::Local => iana_time_zone::get_timezone()
+            .unwrap_or_else(|_| Local::now().offset().to_string())
+            .into(),
+    }
+}
+
+#[allow(clippy::unnecessary_wraps)]
+fn get_timezone_name(ctx: &mut Context) -> Resolved {
+    Ok(get_name_for_timezone(ctx.timezone()).into())
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct GetTimezoneName;
+
+impl Function for GetTimezoneName {
+    fn identifier(&self) -> &'static str {
+        "get_timezone_name"
+    }
+
+    fn examples(&self) -> &'static [Example] {
+        &[Example {
+            title: "Get the VRL timezone name, or for 'local' the local timezone name or offset (e.g., -05:00)",
+            source: r#"get_timezone_name!() != """#,
+            result: Ok("true"),
+        }]
+    }
+
+    fn compile(
+        &self,
+        _state: &TypeState,
+        _ctx: &mut FunctionCompileContext,
+        _: ArgumentList,
+    ) -> Compiled {
+        Ok(GetTimezoneNameFn.as_expr())
+    }
+}
+
+#[derive(Debug, Clone)]
+struct GetTimezoneNameFn;
+
+impl FunctionExpression for GetTimezoneNameFn {
+    fn resolve(&self, ctx: &mut Context) -> Resolved {
+        get_timezone_name(ctx)
+    }
+
+    fn type_def(&self, _: &TypeState) -> TypeDef {
+        TypeDef::bytes().fallible()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::value;
+
+    test_function![
+        get_hostname => GetTimezoneName;
+
+        // the test harness always initializes the VRL timezone to UTC
+        utc {
+            args: func_args![],
+            want: Ok(value!(get_name_for_timezone(&TimeZone::Named(chrono_tz::Tz::UTC)))),
+            tdef: TypeDef::bytes().fallible(),
+        }
+    ];
+}

src/stdlib/mod.rs

@@ -85,6 +85,7 @@ cfg_if::cfg_if! {
         mod get;
         mod get_env_var;
         mod get_hostname;
+        mod get_timezone_name;
         mod hmac;
         mod includes;
         mod integer;
@@ -251,6 +252,8 @@ cfg_if::cfg_if! {
         pub use get::Get;
         pub use get_env_var::GetEnvVar;
         pub use get_hostname::GetHostname;
+        pub use get_timezone_name::GetTimezoneName;
+        pub use get_timezone_name::get_name_for_timezone;
         pub use includes::Includes;
         pub use integer::Integer;
         pub use ip_aton::IpAton;
@@ -418,6 +421,7 @@ pub fn all() -> Vec<Box<dyn Function>> {
         Box::new(Get),
         Box::new(GetEnvVar),
         Box::new(GetHostname),
+        Box::new(GetTimezoneName),
         Box::new(Hmac),
         Box::new(Includes),
         Box::new(Integer),