ipx-directory: the directory of public podcasts ipx servers share (#204)

A new crate and service, crates/directory, live at ipx-dir.sdf1.net. ipx
servers send the public feeds their people subscribe to (POST /v1/snapshot,
replacing what that token sent before); the directory fetches each feed's
title, artwork, category, description and latest twenty items every six
hours with ipx-feed, and lists them A to Z and by subscribers summed over
every server. It holds metadata only, never a file or a file's address.

Tokens are in its config file as SHA-256 hashes, each ro, rw or rwa, and
the file is read again within a minute of a change, so adding and revoking
one is an edit and nothing else; a revoked token takes its server's counts.
At first they were to come from environment variables, which would have
meant recreating the container to add one. A file that does not load keeps
the tokens as they were.

Every address sent is checked with ipx_feed::url_looks_private, the check
ipx makes before sending, so one server's miss does not publish a paid feed
to every other; an rwa token can remove and block what both miss.

Deployed: ipx-directory in the ipx Arcane project, database ipx_directory
(its own login) on the databases project's Postgres, which db-backup
already covers, and a tunnel route with no Access in front. The store's
tests run on Postgres as well as SQLite when IPX_TEST_DATABASE_URL is set.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/directory/src/main.rs

@@ -0,0 +1,109 @@
+//! `ipx-directory`: serve the directory, make a token, or check that a running one answers.
+
+use anyhow::{Context, Result};
+use clap::{Parser, Subcommand};
+use ipx_directory::{Directory, config, store::Store};
+use tracing_subscriber::prelude::*;
+
+#[derive(Parser)]
+#[command(version, about = "ipx's directory of public podcasts")]
+struct Cli {
+    /// The config file: where to listen, the database, and the tokens it accepts. Otherwise
+    /// DIRECTORY_CONFIG, or else /config/directory.toml.
+    #[arg(long)]
+    config: Option<std::path::PathBuf>,
+    #[command(subcommand)]
+    cmd: Option<Cmd>,
+}
+
+#[derive(Subcommand)]
+enum Cmd {
+    /// Serve the directory (the default).
+    Serve,
+    /// Make a token, and print it with the lines that let it in.
+    Token {
+        #[command(subcommand)]
+        cmd: TokenCmd,
+    },
+    /// Check that the directory on this machine answers and can read its database: the
+    /// container's healthcheck.
+    Health,
+}
+
+#[derive(Subcommand)]
+enum TokenCmd {
+    New {
+        /// Who it is for, as the log and their snapshot will name them.
+        name: String,
+        #[arg(long, value_parser = ["ro", "rw", "rwa"])]
+        access: String,
+    },
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let cli = Cli::parse();
+    let config_path = cli
+        .config
+        .or_else(|| std::env::var_os("DIRECTORY_CONFIG").map(Into::into))
+        .unwrap_or_else(|| "/config/directory.toml".into());
+    match cli.cmd.unwrap_or(Cmd::Serve) {
+        Cmd::Serve => serve(&config_path).await,
+        Cmd::Token { cmd: TokenCmd::New { name, access } } => {
+            let token = config::new_token();
+            println!("A token for {name}, to give them; it is not kept anywhere:\n\n    {token}\n");
+            println!("To let it in, add this to {}:\n", config_path.display());
+            println!("[[tokens]]\nname = {name:?}\naccess = {access:?}\ntoken_sha256 = {:?}", config::hash(&token));
+            println!("\nThe directory reads the file again within a minute. Delete the entry to revoke it.");
+            Ok(())
+        }
+        Cmd::Health => {
+            let cfg = config::Config::load(&config_path)?;
+            let port = cfg.bind.rsplit(':').next().unwrap_or("8100");
+            let resp = reqwest::Client::new()
+                .get(format!("http://127.0.0.1:{port}/healthz"))
+                .timeout(std::time::Duration::from_secs(4))
+                .send()
+                .await
+                .context("the directory does not answer")?;
+            anyhow::ensure!(resp.status().is_success(), "the directory answers {}", resp.status());
+            Ok(())
+        }
+    }
+}
+
+async fn serve(path: &std::path::Path) -> Result<()> {
+    // One JSON object a line for Loki when DIRECTORY_LOG_FORMAT=json, as ipx does; text otherwise.
+    let json = std::env::var("DIRECTORY_LOG_FORMAT").is_ok_and(|f| f.eq_ignore_ascii_case("json"));
+    let filter = tracing_subscriber::EnvFilter::try_from_env("DIRECTORY_LOG").unwrap_or_else(|_| "ipx_directory=info".into());
+    tracing_subscriber::registry()
+        .with(filter)
+        .with((!json).then(|| tracing_subscriber::fmt::layer().with_writer(std::io::stderr)))
+        .with(json.then(|| tracing_subscriber::fmt::layer().json().flatten_event(true).with_writer(std::io::stderr)))
+        .init();
+
+    let cfg = config::Config::load(path)?;
+    let tokens = cfg.tokens()?;
+    let url = std::env::var(&cfg.database_url_env)
+        .ok()
+        .filter(|u| !u.trim().is_empty())
+        .with_context(|| format!("{} is not set: the directory needs a database URL", cfg.database_url_env))?;
+    let store = Store::open(&url).await.context("opening the database")?;
+    let dir = Directory::new(store, vec![])?;
+    let dropped = dir.set_tokens(tokens).await?;
+
+    let listener = tokio::net::TcpListener::bind(&cfg.bind).await.with_context(|| format!("listening on {}", cfg.bind))?;
+    tracing::info!(bind = %cfg.bind, tokens = cfg.tokens.len(), dropped, "directory started");
+    tokio::spawn(ipx_directory::refresher(dir.clone()));
+    tokio::spawn(ipx_directory::reloader(dir.clone(), path.to_owned()));
+    axum::serve(listener, ipx_directory::router(dir))
+        .with_graceful_shutdown(async {
+            let mut term = tokio::signal::unix::signal(tokio::signal::unix::SignalKind::terminate()).expect("SIGTERM handler");
+            tokio::select! {
+                _ = term.recv() => {}
+                _ = tokio::signal::ctrl_c() => {}
+            }
+        })
+        .await?;
+    Ok(())
+}