Add basic config parsing (#10)

* Add README with example configuration

* Add high level configuration struct

* Enable loading configuration from TOML

* Add test to parse example configuration

* Add saving configuration todo

* Use String for now in `Config` intead of `SshPublicKey` directly to pass tests

* Add default configuration path

* Add benchmark for loading configuration

* Make all config keys optional

* Add default sources in config

Author: SRv6d

Cargo.lock

@@ -8,7 +8,8 @@ edition = "2021"
 [dependencies]
 async-trait = "0.1.79"
 chrono = "0.4.37"
-clap = { version = "4.5.4", features = ["derive"] }
+clap = { version = "4.5.4", features = ["derive", "env", "string"] }
+figment = { version = "0.10.16", features = ["toml"] }
 reqwest = { version = "0.12.2", features = ["json"] }
 serde = { version = "1.0.197", features = ["derive"] }
 tokio = { version = "1.37.0", features = ["full"] }
@@ -17,9 +18,14 @@ tokio = { version = "1.37.0", features = ["full"] }
 codspeed-criterion-compat = "2.4.1"
 criterion = "0.5.1"
 httpmock = "0.7.0"
+indoc = "2.0.5"
 rstest = "0.19.0"
 tempfile = "3.10.1"
 
 [[bench]]
 name = "write_allowed_signers"
 harness = false
+
+[[bench]]
+name = "load_configuration"
+harness = false

Cargo.toml

@@ -0,0 +1,23 @@
+# Example Configuration
+
+```toml
+users = [
+    { name = "torvalds", sources = ["github"] },
+    { name = "gvanrossum", sources = ["github", "gitlab"] },
+    { name = "graydon", sources = ["github"] },
+    { name = "cwoods", sources = ["acme-corp"] },
+    { name = "rdavis", sources = ["acme-corp"] },
+    { name = "pbrock", sources = ["acme-corp"] }
+]
+organizations = [
+    { name = "rust-lang", sources = ["github"] }
+]
+local = [
+    "jdoe@example.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJHDGMF+tZQL3dcr1arPst+YP8v33Is0kAJVvyTKrxMw"
+]
+
+[[sources]]
+name = "acme-corp"
+provider = "gitlab"
+url = "https://git.acme.corp"
+```

README.md

@@ -0,0 +1,38 @@
+use codspeed_criterion_compat::{criterion_group, criterion_main, Criterion};
+use hanko::Config;
+use indoc::indoc;
+use std::{io::Write, path::Path};
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    let toml = indoc! {r#"
+        users = [
+            { name = "torvalds", sources = ["github"] },
+            { name = "gvanrossum", sources = ["github", "gitlab"] },
+            { name = "graydon", sources = ["github"] },
+            { name = "cwoods", sources = ["acme-corp"] },
+            { name = "rdavis", sources = ["acme-corp"] },
+            { name = "pbrock", sources = ["acme-corp"] }
+        ]
+        organizations = [
+            { name = "rust-lang", sources = ["github"] }
+        ]
+        local = [
+            "jdoe@example.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJHDGMF+tZQL3dcr1arPst+YP8v33Is0kAJVvyTKrxMw"
+        ]
+        
+        [[sources]]
+        name = "acme-corp"
+        provider = "gitlab"
+        url = "https://git.acme.corp"
+        "#};
+    let mut file = tempfile::NamedTempFile::new().unwrap();
+    file.write_all(toml.as_bytes()).unwrap();
+    let path: &Path = &file.into_temp_path();
+
+    c.bench_function("load the example configuration", |b| {
+        b.iter(|| Config::load(path).unwrap());
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

benches/load_configuration.rs

@@ -1,13 +1,22 @@
 use super::{manage_signers::ManageSigners, manage_sources::ManageSources};
-use clap::{Args, Parser, Subcommand};
-use std::path::PathBuf;
+use clap::{
+    builder::{OsStr, Resettable},
+    Args, Parser, Subcommand,
+};
+use std::{env, path::PathBuf};
 
 #[derive(Parser)]
 #[command(version, about, long_about = None)]
 pub struct Cli {
     /// The path to the configuration file.
-    #[arg(short, long, value_name = "FILE")]
-    config: Option<PathBuf>,
+    #[arg(
+        short,
+        long,
+        value_name = "FILE",
+        env = "HANKO_CONFIG",
+        default_value = default_config_path()
+    )]
+    pub config: PathBuf,
 
     #[command(flatten)]
     logging: Logging,
@@ -42,6 +51,21 @@ enum Commands {
     Source(ManageSources),
 }
 
+/// The default configuration file path according to the XDG Base Directory Specification.
+/// If neither `$XDG_CONFIG_HOME` nor `$HOME` are set, `Resettable::Reset` is returned, forcing the user to specify the path.
+fn default_config_path() -> Resettable<OsStr> {
+    let dirname = env!("CARGO_PKG_NAME");
+    let filename = "config.toml";
+
+    if let Ok(xdg_config_home) = env::var("XDG_CONFIG_HOME") {
+        Resettable::Value(format!("{}/{}/{}", xdg_config_home, dirname, filename).into())
+    } else if let Ok(home) = env::var("HOME") {
+        Resettable::Value(format!("{}/.config/{}/{}", home, dirname, filename).into())
+    } else {
+        Resettable::Reset
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;