configuration.rs
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use crate::errors::{ Result, Error };
use clap::{ Parser };
use config::{ Config };
use tracing_subscriber::layer::{ SubscriberExt };
use tracing_subscriber::util::{ SubscriberInitExt };
use std::path::{ PathBuf };
use std::str::{ FromStr };
#[derive(Parser)]
#[command(author, version, about)]
struct Arguments {
/// Additional configuration files to load (may be passed multiple times)
#[arg(id="configuration_file", short, long)]
configuration_files: Vec<String>,
/// Additional configuration parameters to use (may be passed multiple times; overrides configuration files)
#[arg(id="parameter", short, long)]
configuration_parameters: Vec<ConfigurationParameter>,
}
#[derive(Clone)]
struct ConfigurationParameter(String, String);
impl FromStr for ConfigurationParameter {
type Err = clap::Error;
fn from_str(s: &str) -> ::std::result::Result<ConfigurationParameter, clap::Error> {
let parts: Vec<&str> = s.splitn(2, '=').collect();
if parts.len() != 2 {
return Err(clap::Error::new(clap::error::ErrorKind::WrongNumberOfValues));
}
Ok(ConfigurationParameter(parts[0].to_string(), parts[1].to_string()))
}
}
pub(crate) struct Configuration {
pub(crate) content_metadata_file: String,
pub(crate) content_root: PathBuf,
pub(crate) network_host: String,
pub(crate) network_port: u16,
}
pub(crate) fn configure() -> Result<Configuration> {
// Configure tracing (aka logging)
tracing_subscriber::registry()
.with(tracing_subscriber::fmt::layer())
.init();
// Parse command line arguments
let arguments = Arguments::parse();
// Set up default configuration values
let mut builder = Config::builder()
.set_default("content.metadata_file", "metadata.json")?
.set_default("network.host", "localhost")?
.set_default("network.port", 8080)?;
// Prepare the list of configuration files to read
if !arguments.configuration_files.is_empty() {
for path in arguments.configuration_files {
tracing::debug!("Found configuration file: {}", path);
builder = builder.add_source(config::File::with_name(&path));
}
} else {
tracing::warn!("No configuration files detected; using default settings");
}
// Apply configuration parameters specified on the command line
for parameter in arguments.configuration_parameters {
tracing::debug!("Overriding parameter {}: {}", parameter.0, parameter.1);
builder = builder.set_override(parameter.0, parameter.1)?;
}
// Actually read the configuration files
let config = builder.build()?;
// Perform any per-parameter validation
let network_port =
match config.get_int("network.port")?.try_into() {
Ok(port) => Ok(port),
Err(e) => Err(Error::InvalidPort(e)),
}?;
Ok(Configuration {
content_metadata_file: config.get_string("content.metadata_file")?,
content_root: config.get_string("content.root")?.into(),
network_host: config.get_string("network.host")?,
network_port,
})
}