build docker error, not find localtime in unix

[baoyachi]

~ docker run -it ghcr.io/cross-rs/x86_64-unknown-linux-gnu:main /bin/sh
# cd /etc
# ls
X11                     binfmt.d              debian_version  fstab      hosts           issue         legal          magic           opt         profile.d  rc5.d        selinux  sysctl.conf  update-motd.d
adduser.conf            ca-certificates       default         gai.conf   init            issue.net     libaudit.conf  magic.mime      os-release  rc.local   rc6.d        shadow   sysctl.d     xdg
alternatives            ca-certificates.conf  deluser.conf    group      init.d          kernel        localtime      mke2fs.conf     pam.conf    rc0.d      rcS.d        shells   systemd
apt                     cron.daily            dhcp            gshadow    inputrc         ld.so.cache   login.defs     modules-load.d  pam.d       rc1.d      resolv.conf  skel     terminfo
bash.bashrc             cron.weekly           dpkg            gss        insserv         ld.so.conf    logrotate.d    mtab            passwd      rc2.d      rmt          ssl      timezone
bash_completion.d       dbus-1                emacs           host.conf  insserv.conf    ld.so.conf.d  lsb-release    networks        perl        rc3.d      securetty    subgid   tmpfiles.d
bindresvport.blacklist  debconf.conf          environment     hostname   insserv.conf.d  ldap          machine-id     nsswitch.conf   profile     rc4.d      security     subuid   udev 

not find /etc/localtime file.

about code:

    pub fn local() -> Result<Self, TzError> {
        #[cfg(not(unix))]
        let local_time_zone = Self::utc();

        #[cfg(unix)]
        let local_time_zone = Self::from_posix_tz("localtime")?;

        Ok(local_time_zone)
    }

    /// Construct a time zone from the contents of a time zone file
    pub fn from_tz_data(bytes: &[u8]) -> Result<Self, TzError> {
        parse_tz_file(bytes)
    }

    /// Construct a time zone from a POSIX TZ string, as described in [the POSIX documentation of the `TZ` environment variable](https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html).
    pub fn from_posix_tz(tz_string: &str) -> Result<Self, TzError> {
        if tz_string.is_empty() {
            return Err(TzError::TzStringError(TzStringError::InvalidTzString("empty TZ string")));
        }

        if tz_string == "localtime" {
            return parse_tz_file(&fs::read("/etc/localtime")?);
        }

        let read = |mut file: File| -> io::Result<_> {
            let mut bytes = Vec::new();
            file.read_to_end(&mut bytes)?;
            Ok(bytes)
        };

ref: https://github.com/x-hgg-x/tz-rs/blob/master/src/timezone/mod.rs#L500-L518

[x-hgg-x]

The tzdata package is not installed in the docker, so the symlink /etc/localtime is either absent or broken.
In this case, the TimeZone::local() function returns an error, and you need to handle it in your code.
On non-UNIX platforms, since the path /etc/localtime is always invalid, the function always returns UTC.

Note: if you are willing to embed the time zone definitions in your binary, you can use the tzdb::local_tz function, which also works on Windows since it only queries for the current time zone name.