From 7f7cca16fa476c769beab8677e313b16af82e6dd Mon Sep 17 00:00:00 2001
From: Alex Lyn <alex.lyn@antgroup.com>
Date: Thu, 9 Apr 2026 15:47:22 +0800
Subject: [PATCH] kata-deploy: Complete containerd config for erofs snapshotter

Add missing containerd configuration items for erofs snapshotter to
enable fsmerged erofs feature:

Add snapshotter plugin configuration:
 - default_size: "10G" # can be customized
 - max_unmerged_layers: 1 # Fixed with 1

These configurations align with the documentation in
docs/how-to/how-to-use-fsmerged-erofs-with-kata.md Step 2,
ensuring the CI workflow run-k8s-tests-coco-nontee-with-erofs-snapshotter
can properly configure containerd for erofs fsmerged rootfs.

Signed-off-by: Alex Lyn <alex.lyn@antgroup.com>
---
 .../binary/src/artifacts/snapshotters.rs      | 42 +++++++++++++++++--
 1 file changed, 38 insertions(+), 4 deletions(-)

diff --git a/tools/packaging/kata-deploy/binary/src/artifacts/snapshotters.rs b/tools/packaging/kata-deploy/binary/src/artifacts/snapshotters.rs
index fb49f35d5a..c757bcdd97 100644
--- a/tools/packaging/kata-deploy/binary/src/artifacts/snapshotters.rs
+++ b/tools/packaging/kata-deploy/binary/src/artifacts/snapshotters.rs
@@ -12,10 +12,7 @@ use log::info;
 use std::fs;
 use std::path::Path;
 
-pub async fn configure_erofs_snapshotter(
-    _config: &Config,
-    configuration_file: &Path,
-) -> Result<()> {
+pub async fn configure_erofs_snapshotter(config: &Config, configuration_file: &Path) -> Result<()> {
     info!("Configuring erofs-snapshotter");
 
     toml_utils::set_toml_value(
@@ -40,6 +37,43 @@ pub async fn configure_erofs_snapshotter(
         ".plugins.\"io.containerd.snapshotter.v1.erofs\".set_immutable",
         "true",
     )?;
+    // Turn off fsmerge unless we are configuring for a Rust shim below.  Writing 0
+    // first keeps behavior explicit and resets a stale max_unmerged_layers in this
+    // drop-in after switching away from Rust / fsmerged EROFS on the same node.
+    toml_utils::set_toml_value(
+        configuration_file,
+        ".plugins.\"io.containerd.snapshotter.v1.erofs\".max_unmerged_layers",
+        "0",
+    )?;
+
+    // The remaining settings only apply to runtime-rs (rust shim) which
+    // supports fsmerged EROFS.  The go runtime does not, so we leave the
+    // differ and snapshotter plugins at their defaults for it.
+    let is_rust_shim = config.shims_for_arch.iter().any(|s| utils::is_rust_shim(s));
+    if is_rust_shim {
+        // Erofs differ plugin options (requires erofs-utils >= 1.8.2 on the host).
+        toml_utils::set_toml_value(
+            configuration_file,
+            ".plugins.\"io.containerd.differ.v1.erofs\".mkfs_options",
+            "[\"-T0\",\"--mkfs-time\",\"--sort=none\"]",
+        )?;
+        toml_utils::set_toml_value(
+            configuration_file,
+            ".plugins.\"io.containerd.differ.v1.erofs\".enable_tar_index",
+            "false",
+        )?;
+
+        toml_utils::set_toml_value(
+            configuration_file,
+            ".plugins.\"io.containerd.snapshotter.v1.erofs\".default_size",
+            "\"10G\"",
+        )?;
+        toml_utils::set_toml_value(
+            configuration_file,
+            ".plugins.\"io.containerd.snapshotter.v1.erofs\".max_unmerged_layers",
+            "1",
+        )?;
+    }
 
     Ok(())
 }