Author: Andy Green <andy@warmcat.com>
Date: Thu Jul 31 20:47:18 2025 +0100

cgroups: support builder encapsulation


diff --git a/src/builder/b-nspawn.c b/src/builder/b-nspawn.c
index 57a4a26..b595aa0 100644
--- a/src/builder/b-nspawn.c
+++ b/src/builder/b-nspawn.c
@@ -243,9 +243,9 @@ int
 saib_spawn(struct sai_nspawn *ns)
 {
 	struct lws_spawn_piped_info info;
-	char args[290], st[2048], *p;
+	char args[290], st[2048], cgroup[128], *p;
 	const char *respath = "unk";
-	int fd, n;
+	int fd, n, in_cgroup = 1;
 	const char * cmd[] = {
 		"/bin/ps",
 		NULL
@@ -318,16 +318,20 @@ saib_spawn(struct sai_nspawn *ns)
 
 	cmd[0] = args;
 
+	lws_snprintf(cgroup, sizeof(cgroup), "inst-%u-%d", (unsigned int)getpid(), ns->instance_idx);
+
 	memset(&info, 0, sizeof(info));
-	info.vh = builder.vhost;
-	info.env_array = (const char **)env;
-	info.exec_array = cmd;
-	info.protocol_name = "sai-stdxxx";
-	info.max_log_lines = 10000;
-	info.timeout_us = 30 * 60 * LWS_US_PER_SEC;
-	info.reap_cb = sai_lsp_reap_cb;
-	info.opaque = ns;
-	info.plsp = &ns->lsp;
+	info.vh			= builder.vhost;
+	info.env_array		= (const char **)env;
+	info.exec_array		= cmd;
+	info.protocol_name	= "sai-stdxxx";
+	info.max_log_lines	= 10000;
+	info.timeout_us		= 30 * 60 * LWS_US_PER_SEC;
+	info.reap_cb		= sai_lsp_reap_cb;
+	info.opaque		= ns;
+	info.plsp		= &ns->lsp;
+	info.cgroup_name_suffix = cgroup;
+	info.p_cgroup_ret	= &in_cgroup;
 
 	ns->lsp = lws_spawn_piped(&info);
 	if (!ns->lsp) {
@@ -336,7 +340,7 @@ saib_spawn(struct sai_nspawn *ns)
 		return 1;
 	}
 
-	lwsl_notice("%s: lws_spawn_piped started\n", __func__);
+	lwsl_notice("%s: lws_spawn_piped started (cgroup: %d)\n", __func__, in_cgroup);
 
 	return 0;
 }
diff --git a/src/builder/b-sai.c b/src/builder/b-sai.c
index ca4af05..26e34d0 100644
--- a/src/builder/b-sai.c
+++ b/src/builder/b-sai.c
@@ -31,6 +31,10 @@
 #include <limits.h>
 #include <stdlib.h>
 
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+
 #if defined(__linux__)
 #include <unistd.h>
 #endif
@@ -847,6 +851,22 @@ int main(int argc, const char **argv)
 		return 1;
 	}
 
+#if defined(__linux__)
+	/*
+	 * At this point we're still root.  So we should be able
+	 * to register our toplevel cgroup OK
+	 */
+	{
+		struct passwd *pwd = getpwuid(sb.st_uid);
+		struct group *grp = getgrgid(sb.st_gid);
+
+		if (lws_spawn_prepare_self_cgroup(pwd->pw_name, grp->gr_name)) {
+			lwsl_err("%s: failed to initialize cgroup dir %s %s\n", __func__, pwd->pw_name, grp->gr_name);
+			return 1;
+		}
+	}
+#endif
+
 #if !defined(__linux__) && !defined(WIN32)
 	/* we are still root */
 	mkdir(UDS_PATHNAME_LOGPROXY, 0700);