feat(manifest): add allow-listed per-netns sysctls primitive

Routing apps (a rootless VPN exit) need packet forwarding in their own
network namespace, but /proc/sys is read-only inside a rootless
container, so it can only be set at create time. Add `app.sysctls`,
allow-listed to net.ipv4.ip_forward / net.ipv6.conf.all.forwarding with
values "0"/"1", and rejected under host networking where it would change
the host. Rendered on all three create paths: podman CLI --sysctl, the
libpod spec `sysctl` map, and Quadlet `Sysctl=`. Absent by default and
not serialized when empty, so existing manifests and units are unchanged.

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

core/archipelago/src/container/quadlet.rs

@@ -176,6 +176,8 @@ pub struct QuadletUnit {
     /// for rotation-drift detection.
     pub labels: Vec<(String, String)>,
     pub devices: Vec<String>,
+    /// Namespaced sysctls (`Sysctl=k=v`), already allow-listed by the manifest.
+    pub sysctls: Vec<(String, String)>,
     pub add_hosts: Vec<(String, String)>,
     pub network_aliases: Vec<String>,
     pub entrypoint: Option<Vec<String>>,
@@ -307,6 +309,9 @@ impl QuadletUnit {
         for dev in &self.devices {
             let _ = writeln!(s, "AddDevice={dev}");
         }
+        for (k, v) in &self.sysctls {
+            let _ = writeln!(s, "Sysctl={k}={v}");
+        }
         for (name, ip) in &self.add_hosts {
             let _ = writeln!(s, "AddHost={name}:{ip}");
         }
@@ -521,6 +526,11 @@ impl QuadletUnit {
                 })
                 .collect(),
             devices: app.devices.clone(),
+            sysctls: app
+                .sysctls
+                .iter()
+                .map(|(k, v)| (k.clone(), v.clone()))
+                .collect(),
             add_hosts: vec![("host.archipelago".into(), "10.89.0.1".into())],
             // Container always answers to its own name; manifest extras add the
             // short hostnames peers bake in (e.g. indeedhub api/minio/relay).
@@ -1487,6 +1497,7 @@ app:
                 "RELAY_NAME=Archipelago Nostr Relay".into(),
             ],
             devices: vec!["/dev/kvm".into()],
+            sysctls: vec![("net.ipv4.ip_forward".into(), "1".into())],
             add_hosts: vec![("host.archipelago".into(), "10.89.0.1".into())],
             entrypoint: Some(vec!["/usr/local/bin/bitcoind".into()]),
             command: vec!["-server=1".into(), "-rpcbind=0.0.0.0".into()],
@@ -1503,6 +1514,7 @@ app:
         assert!(s.contains("Environment=BITCOIN_RPC_PASS=secret"));
         assert!(s.contains("Environment=\"RELAY_NAME=Archipelago Nostr Relay\""));
         assert!(s.contains("AddDevice=/dev/kvm"));
+        assert!(s.contains("Sysctl=net.ipv4.ip_forward=1"));
         assert!(s.contains("AddHost=host.archipelago:10.89.0.1"));
         assert!(s.contains("ReadOnly=true"));
         assert!(s.contains("NoNewPrivileges=true"));
@@ -1524,6 +1536,7 @@ app:
         assert!(!s.contains("PublishPort="));
         assert!(!s.contains("Environment="));
         assert!(!s.contains("AddDevice="));
+        assert!(!s.contains("Sysctl="));
         assert!(!s.contains("AddHost="));
         assert!(!s.contains("ReadOnly="));
         assert!(!s.contains("NoNewPrivileges="));
@@ -1621,6 +1634,31 @@ app:
         assert!(!s.contains("Network=host"));
     }
 
+    #[test]
+    fn from_manifest_renders_namespaced_sysctls() {
+        let yaml = r#"
+app:
+  id: vpn-exit
+  name: VPN Exit
+  version: 1.0.0
+  container:
+    image: test/vpn:1.0.0
+    network: pasta
+  devices: [/dev/net/tun]
+  sysctls:
+    net.ipv4.ip_forward: "1"
+  security:
+    capabilities: [NET_ADMIN, NET_RAW]
+"#;
+        let m = AppManifest::parse(yaml).expect("manifest must parse");
+        let s = QuadletUnit::from_manifest(&m, "vpn-exit").render();
+
+        assert!(s.contains("Network=pasta"));
+        assert!(s.contains("AddDevice=/dev/net/tun"));
+        assert!(s.contains("Sysctl=net.ipv4.ip_forward=1"));
+        assert!(s.contains("AddCapability=NET_ADMIN"));
+    }
+
     #[test]
     fn portainer_catalog_network_repairs_same_node_routing_without_exposing_backend() {
         let manifest = AppManifest::parse(include_str!("../../../../apps/portainer/manifest.yml"))

core/container/src/manifest.rs

@@ -1,5 +1,5 @@
 use serde::{Deserialize, Serialize};
-use std::collections::{HashMap, HashSet};
+use std::collections::{BTreeMap, HashMap, HashSet};
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -54,6 +54,12 @@ pub struct AppDefinition {
     #[serde(default)]
     pub devices: Vec<String>,
 
+    /// Namespaced kernel parameters for the app's OWN network namespace
+    /// (podman `--sysctl`). Allow-listed to [`ALLOWED_SYSCTLS`] and rejected
+    /// under host networking, where they would change the host itself.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub sysctls: BTreeMap<String, String>,
+
     #[serde(default)]
     pub interfaces: HashMap<String, AppInterface>,
 
@@ -1009,6 +1015,11 @@ impl AppManifest {
         }
         validate_environment(&self.app.environment)?;
         validate_devices(&self.app.devices)?;
+        validate_sysctls(
+            &self.app.sysctls,
+            self.app.container.network.as_deref(),
+            &self.app.security.network_policy,
+        )?;
 
         // Volume tmpfs_options: only meaningful for type: tmpfs.
         for (i, v) in self.app.volumes.iter().enumerate() {
@@ -1342,6 +1353,45 @@ fn validate_devices(devices: &[String]) -> Result<(), ManifestError> {
     Ok(())
 }
 
+/// Sysctls an app may set. Each is scoped to the container's own network
+/// namespace, so it cannot reach the host. Packet forwarding is what a
+/// routing app (a VPN exit) needs, and rootless `/proc/sys` is read-only
+/// inside the container, so it can only be set at create time.
+pub const ALLOWED_SYSCTLS: &[&str] = &["net.ipv4.ip_forward", "net.ipv6.conf.all.forwarding"];
+
+fn validate_sysctls(
+    sysctls: &BTreeMap<String, String>,
+    network: Option<&str>,
+    network_policy: &str,
+) -> Result<(), ManifestError> {
+    if sysctls.is_empty() {
+        return Ok(());
+    }
+    let host_network = match network {
+        Some(n) => n == "host",
+        None => network_policy == "host",
+    };
+    if host_network {
+        return Err(ManifestError::Invalid(
+            "sysctls require the app's own network namespace, not host networking".into(),
+        ));
+    }
+    for (key, value) in sysctls {
+        if !ALLOWED_SYSCTLS.contains(&key.as_str()) {
+            return Err(ManifestError::Invalid(format!(
+                "sysctls.{key} is not allowed (allowed: {})",
+                ALLOWED_SYSCTLS.join(", ")
+            )));
+        }
+        if value != "0" && value != "1" {
+            return Err(ManifestError::Invalid(format!(
+                "sysctls.{key} must be \"0\" or \"1\""
+            )));
+        }
+    }
+    Ok(())
+}
+
 fn validate_bind_source(index: usize, source: &str) -> Result<(), ManifestError> {
     let path = std::path::Path::new(source);
     if !path.is_absolute() {
@@ -2784,6 +2834,72 @@ app:
         assert_eq!(m.app.ports[2].bind, "");
     }
 
+    fn sysctl_manifest(network: &str, sysctls: &str) -> String {
+        format!(
+            r#"
+app:
+  id: sysctl-app
+  name: Sysctl App
+  version: 1.0.0
+  container:
+    image: test/image:1.0.0
+    network: {network}
+  sysctls:
+{sysctls}
+"#
+        )
+    }
+
+    #[test]
+    fn forwarding_sysctls_parse_in_own_netns() {
+        let m = AppManifest::parse(&sysctl_manifest(
+            "pasta",
+            "    net.ipv4.ip_forward: \"1\"\n    net.ipv6.conf.all.forwarding: \"0\"",
+        ))
+        .expect("allow-listed forwarding sysctls must validate");
+        assert_eq!(m.app.sysctls["net.ipv4.ip_forward"], "1");
+        assert_eq!(m.app.sysctls["net.ipv6.conf.all.forwarding"], "0");
+    }
+
+    #[test]
+    fn sysctls_absent_by_default_and_not_serialized() {
+        let m = AppManifest::parse(
+            "app:\n  id: plain\n  name: Plain\n  version: 1.0.0\n  container:\n    image: test/image:1.0.0\n",
+        )
+        .unwrap();
+        assert!(m.app.sysctls.is_empty());
+        assert!(!serde_yaml::to_string(&m).unwrap().contains("sysctls"));
+    }
+
+    #[test]
+    fn unsafe_sysctls_are_rejected() {
+        let cases = [
+            (
+                sysctl_manifest("pasta", "    kernel.core_pattern: \"|/bin/sh\""),
+                "not allowed",
+            ),
+            (
+                sysctl_manifest("pasta", "    net.ipv4.ip_forward: \"2\""),
+                "must be \"0\" or \"1\"",
+            ),
+            (
+                sysctl_manifest("host", "    net.ipv4.ip_forward: \"1\""),
+                "own network namespace",
+            ),
+            (
+                // No explicit network: the host policy still means the host netns.
+                sysctl_manifest("pasta", "    net.ipv4.ip_forward: \"1\"")
+                    .replace("    network: pasta\n", "")
+                    .replace("  sysctls:", "  security:\n    network_policy: host\n  sysctls:"),
+                "own network namespace",
+            ),
+        ];
+        for (yaml, expected) in cases {
+            let msg = AppManifest::parse(&yaml).unwrap_err().to_string();
+            assert!(msg.contains(expected), "expected '{expected}', got: {msg}");
+        }
+    }
+
     #[test]
     fn reviewed_host_bind_exceptions_parse() {
         let yaml = r#"

core/container/src/podman_client.rs

@@ -439,6 +439,7 @@ impl PodmanClient {
             "devices": manifest.app.devices.iter().map(|d| {
                 serde_json::json!({"path": d})
             }).collect::<Vec<_>>(),
+            "sysctl": manifest.app.sysctls,
             "resource_limits": resource_limits,
             "cap_add": cap_add,
             "cap_drop": cap_drop,

core/container/src/runtime.rs

@@ -712,6 +712,9 @@ impl ContainerRuntime for DockerRuntime {
         for device in &manifest.app.devices {
             cmd.arg("--device").arg(device);
         }
+        for (key, value) in &manifest.app.sysctls {
+            cmd.arg("--sysctl").arg(format!("{key}={value}"));
+        }
 
         // Environment variables
         for env in &manifest.app.environment {

docs/APP-PACKAGING-MIGRATION-PLAN.md

@@ -35,6 +35,7 @@ As of the current `1.8-alpha` workstream:
 - Manifest-owned generated files exist through `app.files` and have been used for app config material (e.g. strfry, netbird config regeneration).
 - Local image builds are represented with `container.build`; pulled images are represented with `container.image`.
 - Data ownership repair is represented with `container.data_uid`.
+- Per-app network-namespace kernel parameters are represented with `app.sysctls`, allow-listed to packet forwarding (added for rootless VPN exits such as nostr-vpn).
 - Derived host facts and secret-file-backed environment variables are represented with `container.derived_env` and `container.secret_env`.
 - Catalog metadata generation is implemented by `scripts/generate-app-catalog.py`.
 - App-session launch ports/titles and new-tab launch behavior now have a generated TypeScript metadata path from manifests, with manual overrides preserved for companion UIs and aliases that do not have manifest-owned metadata yet.

docs/app-developer-guide.md

@@ -124,6 +124,7 @@ app:
 | `app.environment` | Static `KEY=value` environment entries |
 | `app.health_check` | HTTP or TCP health check settings |
 | `app.devices` | Explicit device paths |
+| `app.sysctls` | Namespaced packet-forwarding sysctls for the app's own network namespace (allow-listed; not with host networking) |
 | `app.metadata` | Catalog-facing presentation metadata such as icon, category, tier, repo/source, author, feature bullets, and [launch hints](#browser-iframe-and-companion-launch-modes) |
 | `app.interfaces.main` | Optional primary UI launch surface with `port`, `protocol`, and `path` |
 

docs/app-manifest-spec.md

@@ -74,6 +74,7 @@ because a wrong source produces a confident wrong verdict.
 | `environment` | list of string | — | `- KEY=value` pairs (static). |
 | `health_check` | HealthCheck | — | `{ type, endpoint/path, interval, timeout, retries }`. `type` is free-form today; `http` is what the monitor exercises. |
 | `devices` | list of string | — | Host device paths; must start with `/dev/`. |
+| `sysctls` | map | — | Kernel parameters for the app's **own** network namespace (podman `--sysctl`, Quadlet `Sysctl=`). Allow-list: `net.ipv4.ip_forward`, `net.ipv6.conf.all.forwarding`; values `"0"`/`"1"`. Rejected under host networking. Needed by routing apps because rootless `/proc/sys` is read-only inside the container. |
 | `interfaces` | map | — | Launch surfaces, keyed by name (`main`): `{ name, description, type, port, protocol, path }`. |
 | `hooks` | LifecycleHooks | — | Allow-listed lifecycle hooks. See [Hooks](#hooks). |
 | `upstream` | UpstreamSource | — | Where the app comes from, so release tooling can tell when the pin has fallen behind. See [Upstream tracking](#upstream-tracking). |
@@ -116,6 +117,9 @@ Validation (enforced at `AppManifest::validate()`):
   FOWNER, NET_ADMIN, NET_BIND_SERVICE, NET_RAW, SETGID, SETUID, SYS_ADMIN).
 - `network_policy` must be exactly `isolated`, `bridge`, or `host`.
 - No `container:`/`ns:` network modes; devices must be `/dev/*`.
+- `sysctls` keys must be on `ALLOWED_SYSCTLS` (packet forwarding only) and
+  need the app's own network namespace — never host networking, where they
+  would change the host.
 - Bind-mount sources are confined to `/var/lib/archipelago` (reviewed
   exceptions: the rootless podman socket and dbus).
 - `derived_env` templates may only use the placeholder allow-list;

docs/quadlet-compilation.md

@@ -43,6 +43,8 @@ PublishPort=<bind>:<host>:<container>/<proto>
 Environment=<KEY>=<value>          # non-secret env only
 Secret=<secret_name>,type=env,target=<KEY>   # secrets by REFERENCE, never value
 Volume=<source>:<target><opts>
+AddDevice=<path>                   # manifest devices
+Sysctl=<key>=<value>               # manifest sysctls (own netns, allow-listed)
 ReadOnly=true                      # when security.readonly_root
 NoNewPrivileges=true               # when security.no_new_privileges
 HealthCmd=<cmd>                    # from the health_check block