implement basic cli app template

Cargo.toml

@@ -8,6 +8,7 @@ members = ["macros", "utils"]
 
 [features]
 default = []
+cli = ["dep:clap", "dep:figment", "dep:tokio", "dep:color-eyre", "dep:num_cpus"]
 # Very long running.
 get_time_test = []
 
@@ -43,4 +44,10 @@ bytes = { version = "1.10.1", features = ["serde"] }
 url = { version = "2.5.4", features = ["serde"] }
 blake3 = "1.8.2"
 slotmap = { version = "1.0.7", features = ["serde"] }
-instant-acme = "0.7.2"
+
+clap = { version = "4.5.47", features = ["derive"], optional = true }
+figment = { version = "0.10.19", features = ["json", "yaml", "env", "toml"], optional = true }
+tokio = { version = "1.47.1", features = ["rt", "rt-multi-thread"], optional = true }
+color-eyre = { version = "0.6.5", optional = true }
+eyre = { version = "0.6.12" }
+num_cpus = { version = "1.17.0", optional = true }

src/cli/mod.rs

@@ -0,0 +1,94 @@
+use std::{num::NonZeroUsize, path::PathBuf};
+
+use clap::{Args, Parser};
+
+use eyre::Context;
+use figment::{
+    Figment,
+    providers::{Env, Format, Json, Toml, YamlExtended},
+};
+
+use tokio::runtime as rt;
+
+#[derive(Parser)]
+struct AppArgs<A: Args> {
+    #[clap(long, short)]
+    /// Config file(s) for the application.
+    config: Vec<PathBuf>,
+    #[clap(long, short)]
+    /// Number of worker threads app will consume.
+    worker_threads: Option<NonZeroUsize>,
+
+    #[clap(flatten)]
+    args: A,
+}
+
+pub struct App {
+    figment: Figment,
+}
+
+impl App {
+    pub fn env_prefix(mut self, pfx: &str) -> Self {
+        self.figment = self.figment.merge(Env::prefixed(pfx));
+
+        self
+    }
+
+    pub fn run<A, C>(
+        self,
+        f: impl Send + 'static + AsyncFnOnce(A, C) -> eyre::Result<()>,
+    ) -> eyre::Result<()>
+    where
+        A: Args,
+        C: serde::de::DeserializeOwned,
+    {
+        let Self { mut figment } = self;
+        color_eyre::install().wrap_err("failed to install color-eyre")?;
+        let AppArgs {
+            config: configs,
+            worker_threads,
+            args,
+        } = AppArgs::<A>::parse();
+
+        for config in configs {
+            // TODO: support glob? Expand home?
+            let component = config.components().next_back().ok_or_else(|| {
+                eyre::eyre!("{} must contain at least one component", config.display())
+            })?;
+            let last = component.as_os_str().as_encoded_bytes();
+
+            if config.is_dir() {
+                todo!("populate everything from the directory")
+            } else if last.ends_with(b".yaml") || last.ends_with(b".yml") {
+                figment = figment.merge(YamlExtended::file(config.as_path()));
+            } else if last.ends_with(b".json") {
+                figment = figment.merge(Json::file(config.as_path()));
+            } else if last.ends_with(b".toml") {
+                figment = figment.merge(Toml::file(config.as_path()));
+            }
+        }
+
+        let config: C = figment.extract_lossy().wrap_err("failed to load config")?;
+        let rt = match worker_threads.map_or(num_cpus::get(), NonZeroUsize::get) {
+            0 | 1 => rt::Builder::new_current_thread(),
+            n => {
+                let mut b = rt::Builder::new_multi_thread();
+                b.worker_threads(n);
+                b
+            }
+        }
+        .enable_all()
+        .build()
+        .wrap_err("failed to create tokio runtime")?;
+
+        rt.block_on(f(args, config))
+    }
+}
+
+impl Default for App {
+    fn default() -> Self {
+        Self {
+            figment: Figment::new(),
+        }
+    }
+}

src/lib.rs

@@ -25,6 +25,9 @@ pub use perfect_derive::perfect_derive;
 pub use slotmap;
 pub use trait_set::trait_set;
 
+#[cfg(feature = "cli")]
+pub mod cli;
+
 pub mod array;
 pub mod error;
 pub mod utils;

src/sync/mod.rs

@@ -1,5 +1 @@
-pub use eva_utils::sync::{
-    chan,
-    notifies,
-    spin,
-};
+pub use eva_utils::sync::{chan, notifies, spin};

src/utils.rs

@@ -1,5 +1,32 @@
 //! # Uncategorized useful functionality
 
+use eyre::Context as _;
+
+use std::{fmt, path::PathBuf};
+
+use crate::data;
+
+#[data(crate = crate, not(Debug), display("<secret>"))]
+pub enum SecretString {
+    Plaintext(String),
+    File(PathBuf),
+}
+
+impl SecretString {
+    pub fn read(&self) -> eyre::Result<String> {
+        match self {
+            Self::Plaintext(t) => Ok(t.clone()),
+            Self::File(f) => std::fs::read_to_string(f).wrap_err("failed to read secret string"),
+        }
+    }
+}
+
+impl fmt::Debug for SecretString {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{self}")
+    }
+}
+
 /// Hint that this branch is cold.
 #[inline(always)]
 pub const fn cold<T>(v: T) -> T {