feat: run cloud shell commands on the ESP32-C6 Modbus full image

DEVICES.md

@@ -263,6 +263,49 @@ Test note: a TCP probe of a local `c8y remoteaccess server` port opens a
 tunnel of its own, which holds the device's single session for a moment; an
 SSH connection straight after it can find the slot busy.
 
+### Lean cloud shell on the ESP32-C6 (2026-11-11)
+
+The C6 Modbus `tedge-full` image now carries the cloud shell command too,
+with `release/extras/shell-lean.conf` after `shell-diagnostics.conf`. The
+full extra did not fit: +15.9 KB of RAM, and +120 KB of flash, which put the
+image at 82.4 % of its slot (budget 80 %). The lean extra keeps the
+allow-list's purpose and drops what a cloud command cannot use:
+
+- No network or Wi-Fi shell (about 65 KB of flash). `net iface` and
+  `wifi status` print more than a result holds (it is cut at about 220
+  bytes), so `tedge net` (lib/common/net.c, `CONFIG_APP_NET_SHELL_CMD`)
+  answers instead: Wi-Fi state, SSID, channel and RSSI, address and prefix,
+  gateway, DNS server and the gateway ping count.
+- No history, completion, VT100, metakeys, wildcards, stats, shell log
+  backend, device shell, log commands or stack painting; a 1.5 KB shell
+  thread (it only starts the dummy backend; commands run on the client's
+  command thread).
+- Output buffers of 256 B instead of 512 B (the result queue holds two).
+- `kernel heap` joins the allow-list: it reports the kernel heap that the
+  Wi-Fi driver and the tunnel's websocket allocate from.
+
+Against `main` (0.11.1), measured with `scripts/release/build.sh`:
+
+| Image | Flash | RAM (sram0) | malloc arena |
+|---|---|---|---|
+| modbus `tedge-full` | 959,692 B | 435,312 B | 74,128 B |
+| + full shell extra | 1,080,508 B (82.4 %) | +15,928 B | 63,280 B |
+| + lean shell extra | 966,202 B (73.7 %) | +9,360 B | 64,768 B |
+
+Of the 9.4 KB: the command thread's stack 4,096 B (tiny-edge's default, not
+yet measured), the shell thread's stack 1,536 B, the dummy backend 528 B, the
+shell instance 512 B, the result queue 520 B, two thread objects 592 B, the
+job 176 B, and about 1.4 KB of small objects and code in RAM. The Wi-Fi
+driver allocates from the kernel heap (`k_malloc`, about 55 KB, fixed by the
+drivers' minimums), which none of this touches; the shell takes its RAM from
+the libc malloc arena.
+
+On the board (eu-latest, `tedge-modbuse8f60afb8198`): the image installed
+over the air and confirmed, and the device lists `c8y_Command`. The commands,
+a refused command, and a 30-minute run with a firmware download and a tunnel
+(where the full extra failed on the agent image in September) are still to
+be recorded here.
+
 ### Identify measured (2026-10-06)
 
 `device-identify` adds `tedge identify [seconds]` (cloud shell) and the sw0

README.md

@@ -1392,8 +1392,9 @@ c8y operations create --device <device> \
 
 This needs an image with the cloud shell command, which today means the
 images built with `tiny-edge/ports/zephyr/profiles/extras/shell-diagnostics.conf`
-(the S3-DevKitC and QT Py modbus-server and tedge-agent full builds; see
-DEVICES.md). That file puts `tedge identify` on the allow-list. On other
+(the S3-DevKitC and QT Py modbus-server and tedge-agent full builds, and the
+ESP32-C6 modbus-server full build with `release/extras/shell-lean.conf`; see
+DEVICES.md). Both put `tedge identify` on the allow-list. On other
 images the cloud has no shell, so only the button works. The same command
 works on a local console where the image has one.
 

cumulocity/README.md

@@ -116,7 +116,16 @@ the device runs:
 `net ping` is not offered: Zephyr prints the replies after the command
 returns, so the cloud would only ever see the `PING <host>` line.
 
+The ESP32-C6 Modbus `tedge-full` image carries a leaner set
+(`release/extras/shell-lean.conf`), because the full one costs too much RAM
+and flash there (DEVICES.md, "Lean cloud shell on the ESP32-C6"). In place
+of `net iface`, `net conn` and `wifi status` it has:
+
+| Command | Answers |
+|---|---|
+| `tedge net` | Wi-Fi state, SSID, channel and RSSI, address, gateway, DNS server |
+| `kernel heap` | free and peak use of the kernel heap (Wi-Fi driver, tunnel) |
+
 Anything else is refused with the reason. Output travels in one SmartREST
-field, so a long answer is cut. The other boards' images leave it out: on
-the ESP32-C6 its ~16 KB of RAM left too little for the Wi-Fi driver and the
-firmware download (DEVICES.md, "Shell diagnostics measured").
+field of about 220 bytes, so a long answer is cut. The other boards' images
+leave the shell out.

lib/common/Kconfig

@@ -346,6 +346,17 @@ config APP_WIFI_PROV_ERASE_HOLD_S
 
 endif # APP_PROV_HANDOFF
 
+config APP_NET_SHELL_CMD
+	bool "Shell command `tedge net`: the network state in one short answer"
+	depends on TEDGE && SHELL && !NET_SOCKETS_OFFLOAD
+	help
+	  Prints the Wi-Fi network, signal and channel, the address, gateway
+	  and DNS server, and the gateway ping count, in less than a cloud
+	  command's result holds (about 220 bytes). For builds that leave out
+	  the network and Wi-Fi shells to save flash (release/extras/
+	  shell-lean.conf); the cloud runs it once it is on the
+	  TEDGE_SHELL_COMMAND_ALLOW_LIST.
+
 config APP_IDENTIFY
 	bool "Identify the device from the cloud and from its button"
 	default y

lib/common/net.c

@@ -998,3 +998,78 @@ int app_net_init(void)
 }
 
 #endif
+
+#if defined(CONFIG_APP_NET_SHELL_CMD)
+#include <zephyr/shell/shell.h>
+#if defined(CONFIG_DNS_RESOLVER)
+#include <zephyr/net/dns_resolve.h>
+#endif
+
+/* `tedge net`: the network state in one short answer. A cloud command's
+ * result is cut at about 220 bytes, which `net iface` and `wifi status`
+ * overrun on their own, and those shells cost about 65 KB of flash. This
+ * prints what a support call asks first. */
+static int cmd_net(const struct shell *sh, size_t argc, char **argv)
+{
+	struct net_if *iface = net_if_get_default();
+	char ip[16], gw[16];
+	int prefix = 0;
+
+	ARG_UNUSED(argc);
+	ARG_UNUSED(argv);
+
+#if defined(CONFIG_WIFI)
+	struct net_if *wifi = net_if_get_first_wifi();
+	struct wifi_iface_status st = {0};
+
+	if (wifi != NULL &&
+	    net_mgmt(NET_REQUEST_WIFI_IFACE_STATUS, wifi, &st, sizeof(st)) == 0) {
+		if (st.state >= WIFI_STATE_ASSOCIATED) {
+			shell_print(sh, "wifi %s \"%.32s\" ch %u rssi %d dBm",
+				    wifi_state_txt(st.state), st.ssid,
+				    st.channel, st.rssi);
+		} else {
+			shell_print(sh, "wifi %s", wifi_state_txt(st.state));
+		}
+	}
+#endif
+	fmt_ip(ip, sizeof(ip), current_ipv4);
+	if (iface != NULL) {
+		struct net_in_addr self = { .s_addr = current_ipv4 };
+		uint32_t mask = net_ntohl(
+			net_if_ipv4_get_netmask_by_addr(iface, &self).s_addr);
+
+		fmt_ip(gw, sizeof(gw), net_if_ipv4_get_gw(iface).s_addr);
+		while (mask & 0x80000000U) {
+			prefix++;
+			mask <<= 1;
+		}
+		shell_print(sh, "ip %s/%d gw %s", ip, prefix, gw);
+	}
+#if defined(CONFIG_DNS_RESOLVER)
+	struct dns_resolve_context *dns = dns_resolve_get_default();
+
+	for (int i = 0; dns != NULL && i < DNS_RESOLVER_MAX_SERVERS; i++) {
+		const struct net_sockaddr *sa = &dns->servers[i].dns_server;
+
+		if (dns->servers[i].is_mdns || sa->sa_family != NET_AF_INET) {
+			continue;
+		}
+		fmt_ip(ip, sizeof(ip), net_sin(sa)->sin_addr.s_addr);
+		shell_print(sh, "dns %s", ip);
+	}
+#endif
+#if defined(CONFIG_NET_IPV4)
+	shell_print(sh, "gateway ping %d/%u", (int)atomic_get(&ping_ok),
+		    ping_sent);
+#endif
+	if (g_last_reason >= 0) {
+		shell_print(sh, "last wifi reason %d", g_last_reason);
+	}
+	return 0;
+}
+
+/* Hangs off the client's own "tedge" root, which tiny-edge defines. */
+SHELL_SUBCMD_ADD((tedge), net, NULL,
+		 "network state: Wi-Fi, address, gateway, DNS", cmd_net, 1, 0);
+#endif /* CONFIG_APP_NET_SHELL_CMD */

release/devices.yml

@@ -56,7 +56,11 @@ devices:
       - { app: snmp-agent, variant: standalone }
       - app: modbus-server
         variant: tedge-full
-        measured: DEVICES.md#release-builds-measured-on-the-boards-2026-09-21
+        pr: true
+        extra_conf:
+          - "{tiny-edge}/ports/zephyr/profiles/extras/shell-diagnostics.conf"
+          - release/extras/shell-lean.conf
+        measured: DEVICES.md#lean-cloud-shell-on-the-esp32-c6-2026-11-11
       - app: modbus-server
         variant: tedge-ota
         measured: DEVICES.md#release-builds-measured-on-the-boards-2026-09-21

release/extras/shell-lean.conf

@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: Apache-2.0
+#
+# The cloud shell command (c8y_Command) for boards without room for the full
+# shell-diagnostics extra: goes after
+# {tiny-edge}/ports/zephyr/profiles/extras/shell-diagnostics.conf in a build's
+# extra_conf (release/devices.yml), and trims it. Measured on the
+# ESP32-C6 Modbus tedge-full image in DEVICES.md.
+#
+# A cloud command runs on the client's command thread against the dummy
+# backend, and its result is cut at about 220 bytes. So the shell needs no
+# history, completion, terminal handling or log backend, and its own thread
+# only starts the backend.
+CONFIG_SHELL_STACK_SIZE=1536
+CONFIG_SHELL_LOG_BACKEND=n
+CONFIG_SHELL_HISTORY=n
+CONFIG_SHELL_TAB=n
+CONFIG_SHELL_WILDCARD=n
+CONFIG_SHELL_VT100_COMMANDS=n
+CONFIG_SHELL_VT100_COLORS=n
+CONFIG_SHELL_METAKEYS=n
+CONFIG_SHELL_STATS=n
+CONFIG_SHELL_CMDS=n
+CONFIG_SHELL_CMD_BUFF_SIZE=160
+CONFIG_SHELL_ARGC_MAX=12
+CONFIG_DEVICE_SHELL=n
+CONFIG_LOG_CMDS=n
+CONFIG_LOG_RUNTIME_FILTERING=n
+# Only "kernel uptime", "kernel version" and "kernel heap" are allowed, not
+# the thread commands that stack painting serves.
+CONFIG_INIT_STACKS=n
+# What a command printed is cut to one result of about 220 bytes, so
+# capturing more only fills the result queue (two entries).
+CONFIG_SHELL_BACKEND_DUMMY_BUF_SIZE=256
+CONFIG_TEDGE_SHELL_COMMAND_OUTPUT_BYTES=256
+
+# `tedge net` (lib/common/net.c) answers in one short result instead of the
+# network and Wi-Fi shells (`net iface`, `wifi status`), which print more
+# than a result holds and cost about 65 KB of flash.
+CONFIG_NET_SHELL=n
+CONFIG_NET_L2_WIFI_SHELL=n
+CONFIG_APP_NET_SHELL_CMD=y
+
+#   kernel uptime / kernel version   how long it has run, what it runs
+#   kernel heap                      the kernel heap (Wi-Fi driver, tunnel)
+#   tedge net                        Wi-Fi, address, gateway, DNS
+#   tedge params list / tedge diag   the client's parameter sets and state
+#   tedge identify [seconds]         blink the status LED to find the board
+CONFIG_TEDGE_SHELL_COMMAND_ALLOW_LIST="kernel uptime,kernel version,kernel heap,tedge net,tedge params list,tedge diag,tedge identify"

release/size-baseline.json

@@ -74,13 +74,13 @@
     }
   },
   "modbus-server-tedge-full-esp32c6-devkitc": {
-    "image": 959692,
-    "content": 839144,
+    "image": 966203,
+    "content": 862607,
     "ram": {
-      "sram0_0_seg": 435312,
+      "sram0_0_seg": 444672,
       "lp_ram_seg": 36
     },
-    "arena": 74128,
+    "arena": 64768,
     "provisioner": {
       "image": 1013963,
       "content": 909467,