feat(*): init Rust port

This is a Rust port of the original Perl script, legacy cruft is removed
and it focuses on a modern Hydra deployment.

Nonetheless, it knows how to perform migrations based on the channel
versions.

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

.gitignore

@@ -1 +1,6 @@
 result
+
+
+# Added by cargo
+
+/target

Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "nixos-channel-scripts"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+clap = { version = "4.5.13", features = [ "derive" ] }
+log = "0.4.22"
+object_store = { version = "0.10.2", features = [ "aws" ] }
+pretty_env_logger = "0.5.0"
+regex = "1.10.6"
+reqwest = "0.12.5"
+serde = "1.0.204"
+textwrap = "0.16.1"
+tokio = { version = "1.39.2", features = ["full"] }
+toml = "0.8.19"

default.nix

@@ -1,3 +1,11 @@
-(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
-  src = builtins.fetchGit ./.;
-}).defaultNix
+{ pkgs ? import <nixpkgs> {} }:
+{
+  shell = pkgs.mkShell {
+    buildInputs = [
+      pkgs.cargo
+      pkgs.rustc
+      pkgs.openssl
+      pkgs.pkg-config
+    ];
+  };
+}

forkos.toml

@@ -0,0 +1,5 @@
+hydra_uri = "https://hydra.forkos.org"
+binary_cache_uri = "https://cache.forkos.org"
+nixpkgs_dir = "/var/lib/nixpkgs"
+s3_release_bucket_uri = "s3://cache.forkos.org/release"
+s3_channel_bucket_uri = "s3://cache.forkos.org/channel"

shell.nix

@@ -1,3 +0,0 @@
-(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
-  src = builtins.fetchGit ./.;
-}).shellNix

src/actions.rs

@@ -0,0 +1,27 @@
+use std::path::PathBuf;
+
+enum HydraProductType {
+    BrotliJson,
+    SourceDistribution,
+}
+
+impl ToString for HydraProductType {
+    fn to_string(&self) -> String {
+        match self {
+            Self::BrotliJson => "json-br".to_string(),
+            Self::SourceDistribution => "source-dist".to_string(),
+        }
+    }
+}
+
+enum Action {
+    WriteFile {
+        dst_path: PathBuf,
+        contents: String
+    },
+    WriteHydraProduct {
+        dst_path: PathBuf,
+        product_name: String,
+        product_type: Option<HydraProductType>,
+    }
+}

src/config.rs

@@ -0,0 +1,33 @@
+use object_store::aws::{AmazonS3, AmazonS3Builder};
+use serde::Deserialize;
+use std::path::PathBuf;
+
+#[derive(Debug, Deserialize)]
+pub struct MirrorConfig {
+    /// URI to Hydra instance
+    pub hydra_uri: String,
+    /// URI to the binary cache
+    binary_cache_uri: String,
+    /// A path to a checkout of nixpkgs
+    nixpkgs_dir: PathBuf,
+    /// S3 releases bucket URL
+    s3_release_bucket_uri: String,
+    /// S3 channels bucket URL
+    s3_channel_bucket_uri: String,
+}
+
+impl MirrorConfig {
+    pub fn release_bucket(&self) -> AmazonS3 {
+        AmazonS3Builder::from_env()
+            .with_bucket_name(&self.s3_release_bucket_uri)
+            .build()
+            .expect("Failed to connect to the S3 release bucket")
+    }
+
+    pub fn channel_bucket(&self) -> AmazonS3 {
+        AmazonS3Builder::from_env()
+            .with_bucket_name(&self.s3_channel_bucket_uri)
+            .build()
+            .expect("Failed to connect to the S3 channel bucket")
+    }
+}

src/git.rs

@@ -0,0 +1 @@
+

src/hydra.rs

@@ -0,0 +1,168 @@
+use std::{collections::HashMap, path::PathBuf};
+use regex::Regex;
+
+use serde::{de::Error, Deserialize, Deserializer};
+
+use crate::config::MirrorConfig;
+
+pub type ReleaseId = u64;
+pub type EvaluationId = u64;
+pub type BuildId = u64;
+
+fn deser_bool_as_int<'de, D>(deserializer: D) -> Result<bool, D::Error>
+    where D: Deserializer<'de>
+{
+    u8::deserialize(deserializer).map(|b| if b == 1 { true } else { false })
+}
+
+fn deser_bool_as_string<'de, D>(deserializer: D) -> Result<bool, D::Error>
+where D: Deserializer<'de>
+{
+    let s: &str = Deserialize::deserialize(deserializer)?;
+
+    match s {
+        "false" => Ok(false),
+        "true" => Ok(true),
+        _ => Err(Error::unknown_variant(s, &["false", "true"]))
+    }
+}
+
+#[derive(Debug)]
+pub struct Channel {
+    pub name: String
+}
+
+impl Channel {
+    pub fn version(&self) -> String {
+        let re = Regex::new("([a-z]+)-(?<ver>.*)").unwrap();
+        let caps = re.captures(&self.name).expect("Failed to parse the channel name");
+
+        caps["ver"].to_string()
+    }
+
+    pub fn prefix(&self) -> String {
+        let re = Regex::new("(?<name>[a-z]+)-(.*)").unwrap();
+        let caps = re.captures(&self.name).expect("Failed to parse the channel name");
+
+        caps["name"].to_string()
+    }
+}
+
+#[derive(Deserialize, Debug)]
+pub struct Release {
+    pub id: ReleaseId,
+    job: String,
+    #[serde(rename = "releasename")]
+    release_name: Option<String>,
+    #[serde(rename = "starttime")]
+    start_time: u64,
+    #[serde(rename = "stoptime")]
+    stop_time: u64,
+    #[serde(rename = "nixname")]
+    pub nix_name: String,
+    #[serde(rename = "jobsetevals")]
+    jobset_evals: Vec<EvaluationId>,
+    jobset: String,
+    #[serde(deserialize_with = "deser_bool_as_int")]
+    finished: bool,
+    priority: u64,
+    system: String,
+    timestamp: u64,
+    project: String,
+    #[serde(rename = "drvpath")]
+    derivation_path: String,
+    // ignored: buildproducts, buildoutputs, buildmetrics, buildstatus
+}
+
+#[derive(Debug)]
+pub struct GitInput {
+    uri: String,
+    revision: String
+}
+
+// FIXME(Raito): for some reason, #[serde(tag = "type"), rename_all = "lowercase"] doesn't behave
+// correctly, and causes deserialization failures in practice. `untagged` is suboptimal but works
+// because of the way responses works...
+#[derive(Debug, Deserialize)]
+#[serde(untagged, expecting = "An valid jobset input")]
+pub enum Input {
+    Boolean {
+        #[serde(deserialize_with = "deser_bool_as_string")]
+        value: bool
+    },
+    Git { uri: String, revision: String },
+    Nix { value: String },
+}
+
+#[derive(Deserialize, Debug)]
+pub struct Evaluation {
+    pub id: EvaluationId,
+    #[serde(rename="checkouttime")]
+    checkout_time: u64,
+    #[serde(rename="evaltime")]
+    eval_time: u64,
+    flake: Option<String>,
+    #[serde(rename="jobsetevalinputs", default)]
+    pub jobset_eval_inputs: HashMap<String, Input>,
+    timestamp: u64,
+    builds: Vec<BuildId>,
+}
+
+impl Release {
+    pub fn version(&self) -> String {
+        let re = Regex::new(".+-(?<ver>[0-9].+)").unwrap();
+        let caps = re.captures(&self.nix_name).expect("Failed to parse the release name");
+
+        caps["ver"].to_string()
+    }
+
+    pub fn evaluation_url(&self, hydra_base_uri: &str) -> String {
+        let eval_id = self.jobset_evals.first().expect("Failed to obtain the corresponding evaluation, malformed release?");
+        format!("{}/eval/{}", hydra_base_uri, eval_id)
+    }
+
+    /// Directory related to this release.
+    fn directory(&self, channel: &Channel) -> String {
+        match channel.name.as_str() {
+            "nixpkgs-unstable" => "nixpkgs".to_string(),
+            _ => format!("{}/{}", channel.prefix(), channel.version())
+        }
+    }
+
+    pub fn prefix(&self, channel: &Channel) -> object_store::path::Path {
+        format!("{}/{}", self.directory(channel), self.nix_name).into()
+    }
+}
+
+pub fn release_uri(hydra_uri: &str, job_name: &str) -> String {
+    format!("{}/job/{}/latest", hydra_uri, job_name)
+}
+
+pub struct HydraClient<'a> {
+    pub config: &'a MirrorConfig,
+}
+
+impl HydraClient<'_> {
+    pub async fn fetch_release(&self, job_name: &str) -> reqwest::Result<Release> {
+        let client = reqwest::Client::new();
+        let resp = client.get(release_uri(&self.config.hydra_uri, job_name))
+            .header("Accept", "application/json")
+            // TODO: put a proper version
+            .header("User-Agent", "nixos-channel-scripts (rust)")
+            .send()
+            .await?;
+
+        resp.json().await
+    }
+
+    pub async fn fetch_evaluation(&self, release: &Release) -> reqwest::Result<Evaluation> {
+        let client = reqwest::Client::new();
+        let resp = client.get(release.evaluation_url(&self.config.hydra_uri))
+            .header("Accept", "application/json")
+            .header("User-Agent", "nixos-channel-scripts (rust)")
+            .send()
+            .await?;
+
+        resp.json().await
+    }
+}

src/main.rs

@@ -0,0 +1,143 @@
+mod config;
+mod actions;
+mod hydra;
+mod git;
+
+use std::path::PathBuf;
+
+use clap::{Subcommand, Parser, Args};
+use hydra::{Channel, Evaluation, HydraClient, Release};
+use log::{info, trace, warn};
+use object_store::{aws::{AmazonS3, AmazonS3Builder}, ObjectStore};
+
+#[derive(Debug, Args)]
+struct ChannelArgs {
+    /// Channel name to update
+    channel_name: String,
+    /// Job name to fetch from the Hydra instance configured
+    job_name: String,
+    /// If a channel rollback is detected, do not bail out and proceed to rollback the channel
+    #[arg(short, long, default_value_t = false)]
+    ignore_rollback_protection: bool
+}
+
+#[derive(Debug, Args)]
+struct GlobalOpts {
+    /// TOML configuration file for channel updates
+    #[arg(short, long)]
+    config_file: PathBuf,
+    /// Whether to execute no remote side effects (S3 uploads, redirections), etc.
+    #[arg(short, long, default_value_t = false)]
+    dry_run: bool,
+}
+
+#[derive(Debug, Parser)]
+#[command(version, about, long_about = None)]
+struct App {
+    #[command(flatten)]
+    global_opts: GlobalOpts,
+    #[command(subcommand)]
+    command: Commands
+}
+
+#[derive(Debug, Subcommand)]
+enum Commands {
+    /// Print the plan for the given channel name and job name
+    Plan(ChannelArgs),
+    /// Apply the plan that would be generated for the given channel name and job name
+    Apply(ChannelArgs),
+}
+
+#[derive(Debug)]
+struct PreflightCheckContext<'a> {
+    target_channel: &'a Channel,
+    new_release: &'a Release,
+    new_evaluation: &'a Evaluation,
+    current_release_path: Option<object_store::path::Path>,
+}
+
+async fn run_preflight_checks(channel: &Channel, release: &Release, evaluation: &Evaluation, channel_bucket: AmazonS3) -> bool {
+    info!("Running pre-flight checks...");
+    let channel_name = object_store::path::Path::parse(&channel.name).expect("Channel name should be a valid S3 path");
+    let mut context = PreflightCheckContext {
+        target_channel: channel,
+        new_release: release,
+        new_evaluation: evaluation,
+        current_release_path: None
+    };
+    match channel_bucket.get_opts(&channel_name, object_store::GetOptions { head: true, ..Default::default() }).await {
+        Ok(object_store::GetResult { attributes, meta, .. }) => {
+            info!("Release found: {:?}", meta);
+            trace!("Attributes: {:#?}", attributes);
+            if let Some(redirection_target) = attributes.get(&object_store::Attribute::Metadata("x-amz-website-redirect-location".into())) {
+                context.current_release_path = Some(redirection_target.to_string().into());
+            }
+        },
+        Err(err) => {
+            warn!("Error while asking the channel bucket: {}", err);
+            todo!();
+        }
+    }
+
+    trace!("Preflight context check assembled: {:?}", context);
+    // TODO: run anti rollback protection
+    true
+}
+
+#[tokio::main]
+async fn main() -> std::io::Result<()> {
+    pretty_env_logger::init();
+
+    let args = App::parse();
+
+    let config: config::MirrorConfig = toml::from_str(&std::fs::read_to_string(args.global_opts.config_file)
+        .expect("Failed to read the configuration file"))
+        .expect("Failed to deserialize the configuration file");
+
+    println!("config: {:?}", config);
+
+    let hydra_client: HydraClient = HydraClient {
+        config: &config
+    };
+
+    match args.command {
+        Commands::Plan(channel) => {
+            let chan = Channel {
+                name: channel.channel_name,
+            };
+            info!("Planning for channel {} using job {}", chan.name, channel.job_name);
+            let release = hydra_client.fetch_release(&channel.job_name)
+                .await.expect("Failed to fetch release");
+            trace!("{:#?}", release);
+            let evaluation = hydra_client.fetch_evaluation(&release)
+                .await.expect("Failed to fetch evaluation");
+            trace!("{:?}", evaluation.jobset_eval_inputs);
+
+            if let hydra::Input::Git { revision, .. } = evaluation.jobset_eval_inputs.get("nixpkgs").expect("Expected a nixpkgs repository") {
+                info!("Release information:\n- Release is: {} (build {})\n- Eval is: {}\n- Prefix is: {}\n- Git commit is {}\n", 
+                    release.nix_name, release.id, evaluation.id, release.prefix(&chan), revision);
+
+                let release_bucket = config.release_bucket();
+
+                // If the release already exists, skip it.
+                if release_bucket.head(&release.prefix(&chan)).await.is_ok() {
+                    log::warn!("Release already exists, skipping");
+                    return Ok(());
+                }
+
+                // Runs the preflight checks.
+                let channel_bucket = config.channel_bucket();
+                if run_preflight_checks(&chan, &release, &evaluation, channel_bucket).await {
+                    info!("Preflight checks passed"); 
+                } else {
+                    log::error!("Preflight check failed, cannot continue, pass `--force` if you want to bypass preflight checks");
+                }
+            } else {
+                panic!("Nixpkgs input is not of type Git");
+            }
+        },
+        Commands::Apply(_) => todo!(),
+    }
+
+    Ok(())
+}