Struct Loader 

pub struct Loader { /* private fields */ }

Builds a Config out of a base file and drop-in directories.

let config = Loader::new()
    .base("/etc/zerodds/zerodds.yaml")
    .drop_in_dir("/etc/zerodds/zerodds.d")
    .drop_in_dir("/run/zerodds/zerodds.d")
    .load()?;
// Where did this come from?
println!("{:?}", config.origin_of("transport.mtu"));

Implementations

impl Loader

pub fn new() -> Self

A loader with nothing in it yet.

pub fn base(self, path: impl AsRef<Path>) -> Self

The base file, read before every drop-in.

Absent by default: a package can ship only drop-ins, and a site can run with only a base.

pub fn require_base(self) -> Self

Fail rather than continue when the base file is not there.

Off by default, because “no configuration” is a legitimate state and a daemon that starts on its built-in defaults is what an empty /etc/zerodds should produce. On for a caller who passed --config and means it.

pub fn drop_in_dir(self, path: impl AsRef<Path>) -> Self

Adds a drop-in directory, after the ones already added.

Directories are read in the order they are added — a package directory, then a site one, then a runtime one — and inside each directory the files are read sorted by name. 10-net.yaml before 20-net.yaml before 99-local.yaml, which is the ordering every systemd drop-in already follows and therefore the one an operator will assume without being told.

A directory that does not exist is not an error. Half the point of drop-ins is that /run/... exists only sometimes.

pub fn extension(self, ext: Option<&str>) -> Self

Only files with this extension are read from drop-in directories.

yaml by default. None reads every file, which is what a directory of .conf fragments needs. Either way .rpmnew, .dpkg-dist and editor backups stay out when the default is kept — a package upgrade leaving zerodds.yaml.rpmnew behind must not quietly change what runs.

pub fn load(&self) -> Result<Config, ConfigError>

Reads everything and merges it.

Errors

ConfigError::Io for an unreadable file (and for a missing base after Self::require_base), ConfigError::Syntax for text outside the subset, ConfigError::IncludeCycle and ConfigError::IncludeTooDeep for include chains that do not end.

pub fn load_onto(&self, config: Config) -> Result<Config, ConfigError>

Reads everything and merges it over config, which keeps its sources and loses every value a file sets again. The environment layer goes in here, so that the files win over it and a drop-in’s +name appends to what it set.

Errors

As Self::load.

Trait Implementations

impl Clone for Loader

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Loader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Loader

fn default() -> Self

Returns the “default value” for a type.