canic_backup/discovery/

mod.rs

//! Module: discovery
//!
//! Responsibility: convert registry observations into backup target sets.
//! Does not own: snapshot IO, manifest validation, or persisted backup state.
//! Boundary: prepares discovery projections consumed by backup planning.

#[cfg(test)]
mod tests;

use crate::{
    manifest::{
        DeploymentMember, DeploymentSection, IdentityMode, SourceSnapshot, VerificationCheck,
    },
    registry::RegistryEntry,
    topology::{TopologyHasher, TopologyRecord},
};
use std::collections::{BTreeMap, BTreeSet, VecDeque};
use thiserror::Error as ThisError;

///
/// DiscoveredFleet
///
/// Registry-derived fleet snapshot before it is serialized into a manifest.
/// Owned by backup discovery and consumed by manifest construction.
///

#[derive(Clone, Debug)]
pub struct DiscoveredFleet {
    pub topology_records: Vec<TopologyRecord>,
    pub members: Vec<DiscoveredMember>,
}

impl DiscoveredFleet {
    /// Convert discovered topology and member policy into a manifest fleet section.
    pub fn into_deployment_section(self) -> Result<DeploymentSection, DiscoveryError> {
        validate_discovered_members(&self.members)?;

        let topology_hash = TopologyHasher::hash(&self.topology_records);
        let members = self
            .members
            .into_iter()
            .map(DiscoveredMember::into_deployment_member)
            .collect();

        Ok(DeploymentSection {
            topology_hash_algorithm: topology_hash.algorithm,
            topology_hash_input: topology_hash.input,
            discovery_topology_hash: topology_hash.hash.clone(),
            pre_snapshot_topology_hash: topology_hash.hash.clone(),
            topology_hash: topology_hash.hash,
            members,
        })
    }
}

///
/// DiscoveredMember
///
/// One discovered deployment member with backup policy and snapshot metadata.
/// Owned by backup discovery and projected into deployment manifest members.
///

#[derive(Clone, Debug)]
pub struct DiscoveredMember {
    pub role: String,
    pub canister_id: String,
    pub parent_canister_id: Option<String>,
    pub subnet_canister_id: Option<String>,
    pub controller_hint: Option<String>,
    pub identity_mode: IdentityMode,
    pub verification_checks: Vec<VerificationCheck>,
    pub snapshot_plan: SnapshotPlan,
}

impl DiscoveredMember {
    /// Project this discovery member into the manifest restore contract.
    fn into_deployment_member(self) -> DeploymentMember {
        DeploymentMember {
            role: self.role,
            canister_id: self.canister_id,
            parent_canister_id: self.parent_canister_id,
            subnet_canister_id: self.subnet_canister_id,
            controller_hint: self.controller_hint,
            identity_mode: self.identity_mode,
            verification_checks: self.verification_checks,
            source_snapshot: SourceSnapshot {
                snapshot_id: self.snapshot_plan.snapshot_id,
                module_hash: self.snapshot_plan.module_hash,
                code_version: self.snapshot_plan.code_version,
                artifact_path: self.snapshot_plan.artifact_path,
                checksum_algorithm: self.snapshot_plan.checksum_algorithm,
                checksum: self.snapshot_plan.checksum,
            },
        }
    }
}

///
/// SnapshotPlan
///
/// Source snapshot metadata planned for one discovered deployment member.
/// Owned by backup discovery and copied into manifest source snapshots.
///

#[derive(Clone, Debug)]
pub struct SnapshotPlan {
    pub snapshot_id: String,
    pub module_hash: Option<String>,
    pub code_version: Option<String>,
    pub artifact_path: String,
    pub checksum_algorithm: String,
    pub checksum: Option<String>,
}

///
/// SnapshotTarget
///
/// Registry target selected for snapshot capture.
/// Owned by backup discovery and consumed by snapshot planning.
///

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SnapshotTarget {
    pub canister_id: String,
    pub role: Option<String>,
    pub parent_canister_id: Option<String>,
    pub module_hash: Option<String>,
}

///
/// DiscoveryError
///
/// Typed discovery failure returned while selecting backup targets.
/// Owned by backup discovery and surfaced to snapshot and planning callers.
///

#[derive(Debug, ThisError)]
pub enum DiscoveryError {
    #[error("discovered fleet has no members")]
    EmptyFleet,

    #[error("duplicate discovered canister id {0}")]
    DuplicateCanisterId(String),

    #[error("discovered member {0} has no verification checks")]
    MissingVerificationChecks(String),

    #[error("registry JSON did not contain the requested canister {0}")]
    CanisterNotInRegistry(String),

    #[error(transparent)]
    Json(#[from] serde_json::Error),
}

/// Resolve selected target and children from registry entries.
pub fn targets_from_registry(
    registry: &[RegistryEntry],
    canister_id: &str,
    recursive: bool,
) -> Result<Vec<SnapshotTarget>, DiscoveryError> {
    let by_pid = registry
        .iter()
        .map(|entry| (entry.pid.as_str(), entry))
        .collect::<BTreeMap<_, _>>();

    let root = by_pid
        .get(canister_id)
        .ok_or_else(|| DiscoveryError::CanisterNotInRegistry(canister_id.to_string()))?;

    let mut targets = Vec::new();
    let mut seen = BTreeSet::new();
    targets.push(SnapshotTarget {
        canister_id: root.pid.clone(),
        role: root.role.clone(),
        parent_canister_id: root.parent_pid.clone(),
        module_hash: root.module_hash.clone(),
    });
    seen.insert(root.pid.clone());

    let mut queue = VecDeque::from([root.pid.clone()]);
    while let Some(parent) = queue.pop_front() {
        for child in registry
            .iter()
            .filter(|entry| entry.parent_pid.as_deref() == Some(parent.as_str()))
        {
            if seen.insert(child.pid.clone()) {
                targets.push(SnapshotTarget {
                    canister_id: child.pid.clone(),
                    role: child.role.clone(),
                    parent_canister_id: child.parent_pid.clone(),
                    module_hash: child.module_hash.clone(),
                });
                if recursive {
                    queue.push_back(child.pid.clone());
                }
            }
        }
    }

    Ok(targets)
}

// Validate discovery output before building a manifest projection.
fn validate_discovered_members(members: &[DiscoveredMember]) -> Result<(), DiscoveryError> {
    if members.is_empty() {
        return Err(DiscoveryError::EmptyFleet);
    }

    let mut canister_ids = BTreeSet::new();
    for member in members {
        if !canister_ids.insert(member.canister_id.clone()) {
            return Err(DiscoveryError::DuplicateCanisterId(
                member.canister_id.clone(),
            ));
        }
        if member.verification_checks.is_empty() {
            return Err(DiscoveryError::MissingVerificationChecks(
                member.canister_id.clone(),
            ));
        }
    }

    Ok(())
}