refactor(driver-utils): centralize container mount path constants (#1841)

Move duplicate in-container path constants from the Docker, Podman,
Kubernetes, and VM driver crates into openshell-core::driver_utils:

- TLS_CA_MOUNT_PATH, TLS_CERT_MOUNT_PATH, TLS_KEY_MOUNT_PATH,
  SANDBOX_TOKEN_MOUNT_PATH — identical string literals that were
  copy-pasted between openshell-driver-docker and
  openshell-driver-podman.

- SUPERVISOR_CONTAINER_DIR (/opt/openshell/bin) and
  SUPERVISOR_CONTAINER_BINARY (/opt/openshell/bin/openshell-sandbox) —
  replaces three diverging local constants across docker, kubernetes,
  podman, and vm-rootfs that referred to the same paths under different
  names with different string values (the k8s constant was the directory;
  the docker/vm constant was the full binary path).

Each driver crate now assigns its local constant from the canonical core
value, keeping existing names visible to tests without any call-site
churn. The openshell-core constants carry doc comments explaining when
to use the dir vs. the full binary path.

Signed-off-by: Eric Curtin <eric.curtin@docker.com>

Author: ericcurtin

crates/openshell-core/src/driver_utils.rs

@@ -36,6 +36,42 @@ pub const LABEL_SANDBOX_NAMESPACE: &str = "openshell.ai/sandbox-namespace";
 /// path used when building the `openshell-sandbox` image layer.
 pub const SUPERVISOR_IMAGE_BINARY_PATH: &str = "/openshell-sandbox";
 
+/// Directory inside sandbox containers where the supervisor binary is mounted.
+///
+/// Compute drivers that side-load the supervisor into a shared volume mount
+/// the binary here so the sandbox container can execute it from a fixed path.
+pub const SUPERVISOR_CONTAINER_DIR: &str = "/opt/openshell/bin";
+
+/// Full path to the supervisor binary inside sandbox containers.
+///
+/// Equals `SUPERVISOR_CONTAINER_DIR + "/openshell-sandbox"`. Use this when
+/// the full executable path is needed (Docker entrypoint, Podman entrypoint,
+/// VM rootfs injection). Use `SUPERVISOR_CONTAINER_DIR` when only the
+/// directory mount-point is needed (Kubernetes emptyDir volume mount).
+pub const SUPERVISOR_CONTAINER_BINARY: &str = "/opt/openshell/bin/openshell-sandbox";
+
+// ---------------------------------------------------------------------------
+// In-container mount paths for guest TLS materials and the sandbox token.
+//
+// All container-based drivers (Docker, Podman, Kubernetes) mount the gateway's
+// mTLS client credentials at these fixed paths inside every sandbox container.
+// The supervisor reads these paths on startup to establish its gRPC-over-mTLS
+// connection back to the gateway. The paths must remain stable across driver
+// versions since the supervisor binary is built and packaged separately.
+// ---------------------------------------------------------------------------
+
+/// Container-side mount path for the guest mTLS CA certificate.
+pub const TLS_CA_MOUNT_PATH: &str = "/etc/openshell/tls/client/ca.crt";
+
+/// Container-side mount path for the guest mTLS client certificate.
+pub const TLS_CERT_MOUNT_PATH: &str = "/etc/openshell/tls/client/tls.crt";
+
+/// Container-side mount path for the guest mTLS client private key.
+pub const TLS_KEY_MOUNT_PATH: &str = "/etc/openshell/tls/client/tls.key";
+
+/// Container-side mount path for the per-sandbox JWT token.
+pub const SANDBOX_TOKEN_MOUNT_PATH: &str = "/etc/openshell/auth/sandbox.jwt";
+
 /// Return the XDG state path for a driver's sandbox JWT token file.
 ///
 /// The resulting path is `$XDG_STATE_HOME/openshell/<driver_subdir>[/<namespace>]/<sandbox_id>/sandbox.jwt`.

crates/openshell-driver-docker/src/lib.rs

@@ -59,11 +59,11 @@ const WATCH_BUFFER: usize = 128;
 const WATCH_POLL_INTERVAL: Duration = Duration::from_secs(2);
 const WATCH_POLL_MAX_BACKOFF: Duration = Duration::from_secs(30);
 
-const SUPERVISOR_MOUNT_PATH: &str = "/opt/openshell/bin/openshell-sandbox";
-const TLS_CA_MOUNT_PATH: &str = "/etc/openshell/tls/client/ca.crt";
-const TLS_CERT_MOUNT_PATH: &str = "/etc/openshell/tls/client/tls.crt";
-const TLS_KEY_MOUNT_PATH: &str = "/etc/openshell/tls/client/tls.key";
-const SANDBOX_TOKEN_MOUNT_PATH: &str = "/etc/openshell/auth/sandbox.jwt";
+const SUPERVISOR_MOUNT_PATH: &str = openshell_core::driver_utils::SUPERVISOR_CONTAINER_BINARY;
+const TLS_CA_MOUNT_PATH: &str = openshell_core::driver_utils::TLS_CA_MOUNT_PATH;
+const TLS_CERT_MOUNT_PATH: &str = openshell_core::driver_utils::TLS_CERT_MOUNT_PATH;
+const TLS_KEY_MOUNT_PATH: &str = openshell_core::driver_utils::TLS_KEY_MOUNT_PATH;
+const SANDBOX_TOKEN_MOUNT_PATH: &str = openshell_core::driver_utils::SANDBOX_TOKEN_MOUNT_PATH;
 const SANDBOX_COMMAND: &str = "sleep infinity";
 const SUPERVISOR_PATH: &str = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin";
 const HOST_OPENSHELL_INTERNAL: &str = "host.openshell.internal";

crates/openshell-driver-kubernetes/src/driver.rs

@@ -769,7 +769,7 @@ fn extract_image_size(message: &str) -> Option<u64> {
 }
 
 /// Path where the supervisor binary is mounted inside the agent container.
-const SUPERVISOR_MOUNT_PATH: &str = "/opt/openshell/bin";
+const SUPERVISOR_MOUNT_PATH: &str = openshell_core::driver_utils::SUPERVISOR_CONTAINER_DIR;
 
 /// Name of the volume used to side-load the supervisor binary.
 const SUPERVISOR_VOLUME_NAME: &str = "openshell-supervisor-bin";

crates/openshell-driver-podman/src/container.rs

@@ -46,11 +46,16 @@ const CONTAINER_PREFIX: &str = "openshell-sandbox-";
 /// Volume name prefix.
 const VOLUME_PREFIX: &str = "openshell-sandbox-";
 
-/// Container-side mount paths for client TLS materials.
-const TLS_CA_MOUNT_PATH: &str = "/etc/openshell/tls/client/ca.crt";
-const TLS_CERT_MOUNT_PATH: &str = "/etc/openshell/tls/client/tls.crt";
-const TLS_KEY_MOUNT_PATH: &str = "/etc/openshell/tls/client/tls.key";
-const SANDBOX_TOKEN_MOUNT_PATH: &str = "/etc/openshell/auth/sandbox.jwt";
+/// Container-side mount paths for client TLS materials and the sandbox token.
+const TLS_CA_MOUNT_PATH: &str = openshell_core::driver_utils::TLS_CA_MOUNT_PATH;
+const TLS_CERT_MOUNT_PATH: &str = openshell_core::driver_utils::TLS_CERT_MOUNT_PATH;
+const TLS_KEY_MOUNT_PATH: &str = openshell_core::driver_utils::TLS_KEY_MOUNT_PATH;
+const SANDBOX_TOKEN_MOUNT_PATH: &str = openshell_core::driver_utils::SANDBOX_TOKEN_MOUNT_PATH;
+
+/// Directory inside sandbox containers where the supervisor binary is mounted.
+const SUPERVISOR_MOUNT_DIR: &str = openshell_core::driver_utils::SUPERVISOR_CONTAINER_DIR;
+/// Full path to the supervisor binary inside sandbox containers.
+const SUPERVISOR_BINARY_PATH: &str = openshell_core::driver_utils::SUPERVISOR_CONTAINER_BINARY;
 
 /// Build a Podman container name from the sandbox name.
 #[must_use]
@@ -443,17 +448,17 @@ pub fn build_container_spec_with_token(
         // /opt/openshell/bin/openshell-sandbox.
         image_volumes: vec![ImageVolume {
             source: config.supervisor_image.clone(),
-            destination: "/opt/openshell/bin".into(),
+            destination: SUPERVISOR_MOUNT_DIR.into(),
             rw: false,
         }],
         hostname: format!("sandbox-{}", sandbox.name),
         // Override the image's ENTRYPOINT so the supervisor binary runs
         // directly. Sandbox images (e.g. the community base image) set
         // ENTRYPOINT ["/bin/bash"], and Podman's `command` field only
         // overrides CMD — which gets appended as args to the entrypoint.
-        // Without this, the container would run `/bin/bash /opt/openshell/bin/openshell-sandbox`
-        // and bash would fail trying to interpret the binary as a script.
-        entrypoint: vec!["/opt/openshell/bin/openshell-sandbox".into()],
+        // Without this, the container would run the entrypoint binary with
+        // the supervisor path as an argument instead of executing it directly.
+        entrypoint: vec![SUPERVISOR_BINARY_PATH.into()],
         command: vec![],
         // Force the supervisor to run as root (UID 0). Sandbox images may
         // set a non-root USER directive (e.g. `USER sandbox`), but the
@@ -1162,7 +1167,7 @@ mod tests {
         );
         assert_eq!(
             vol["destination"].as_str(),
-            Some("/opt/openshell/bin"),
+            Some(SUPERVISOR_MOUNT_DIR),
             "image volume destination should be /opt/openshell/bin"
         );
         assert_eq!(

crates/openshell-driver-vm/src/rootfs.rs

@@ -14,7 +14,7 @@ const SUPERVISOR: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/openshell-sa
 const UMOCI: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/umoci.zst"));
 const ROOTFS_VARIANT_MARKER: &str = ".openshell-rootfs-variant";
 const SANDBOX_GUEST_INIT_PATH: &str = "/srv/openshell-vm-sandbox-init.sh";
-const SANDBOX_SUPERVISOR_PATH: &str = "/opt/openshell/bin/openshell-sandbox";
+const SANDBOX_SUPERVISOR_PATH: &str = openshell_core::driver_utils::SUPERVISOR_CONTAINER_BINARY;
 const SANDBOX_UMOCI_PATH: &str = "/opt/openshell/bin/umoci";
 const SANDBOX_OWNER_NORMALIZED_MARKER: &str = "/opt/openshell/.sandbox-owner-normalized";
 const ROOTFS_IMAGE_MIN_SIZE_BYTES: u64 = 512 * 1024 * 1024;