feat: implement OTA updates over HTTP(S), initiated over MQTT

components/ota_manager/CMakeLists.txt

@@ -0,0 +1,5 @@
+idf_component_register(
+    SRCS "src/ota_manager.c"
+    INCLUDE_DIRS "include"
+    REQUIRES esp_https_ota app_update mqtt_publisher esp_system
+)

components/ota_manager/include/ota_manager.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include "esp_err.h"
+
+/**
+ * Begin an OTA update in a background task.
+ * Applies a MAC-derived jitter delay before downloading so a fleet-wide
+ * trigger staggers reboots instead of dropping all coverage at once.
+ * Reports status via mqtt_publisher_send_ota_status().
+ * On success the device reboots; on failure it stays on the current firmware.
+ */
+esp_err_t ota_manager_start(const char *url, const char *version);

components/ota_manager/src/ota_manager.c

@@ -0,0 +1,84 @@
+#include "ota_manager.h"
+#include "mqtt_publisher.h"
+#include "esp_https_ota.h"
+#include "esp_ota_ops.h"
+#include "esp_mac.h"
+#include "esp_log.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include <string.h>
+#include <stdlib.h>
+
+#define TAG "ota_manager"
+
+/* Prevent concurrent OTA attempts */
+static volatile bool s_ota_running = false;
+
+typedef struct {
+    char url[256];
+    char version[32];
+} ota_task_arg_t;
+
+static void ota_task(void *arg)
+{
+    ota_task_arg_t *params = (ota_task_arg_t *)arg;
+
+    /* Spread reboots across up to 60 s using last 3 MAC bytes as seed */
+    uint8_t mac[6];
+    esp_read_mac(mac, ESP_MAC_WIFI_STA);
+    uint32_t jitter_ms = ((uint32_t)(mac[3] ^ mac[4] ^ mac[5])) % 60000;
+    if (jitter_ms > 0) {
+        ESP_LOGI(TAG, "OTA jitter: %lu ms", jitter_ms);
+        mqtt_publisher_send_ota_status("pending", params->version);
+        vTaskDelay(pdMS_TO_TICKS(jitter_ms));
+    }
+
+    ESP_LOGI(TAG, "Starting OTA from %s", params->url);
+    mqtt_publisher_send_ota_status("downloading", params->version);
+
+    esp_http_client_config_t http_cfg = {
+        .url            = params->url,
+        .timeout_ms     = 30000,
+        .keep_alive_enable = true,
+    };
+    esp_https_ota_config_t ota_cfg = {
+        .http_config = &http_cfg,
+    };
+
+    esp_err_t err = esp_https_ota(&ota_cfg);
+    if (err == ESP_OK) {
+        ESP_LOGI(TAG, "OTA succeeded, rebooting");
+        mqtt_publisher_send_ota_status("rebooting", params->version);
+        vTaskDelay(pdMS_TO_TICKS(500)); /* let MQTT publish flush */
+        esp_restart();
+    } else {
+        ESP_LOGE(TAG, "OTA failed: %s", esp_err_to_name(err));
+        mqtt_publisher_send_ota_status("failed", params->version);
+    }
+
+    free(params);
+    s_ota_running = false;
+    vTaskDelete(NULL);
+}
+
+esp_err_t ota_manager_start(const char *url, const char *version)
+{
+    if (s_ota_running) {
+        ESP_LOGW(TAG, "OTA already in progress, ignoring");
+        return ESP_ERR_INVALID_STATE;
+    }
+
+    ota_task_arg_t *params = malloc(sizeof(ota_task_arg_t));
+    if (!params) return ESP_ERR_NO_MEM;
+
+    strncpy(params->url,     url,     sizeof(params->url)     - 1);
+    strncpy(params->version, version ? version : "", sizeof(params->version) - 1);
+
+    s_ota_running = true;
+    if (xTaskCreate(ota_task, "ota_task", 8192, params, 5, NULL) != pdPASS) {
+        free(params);
+        s_ota_running = false;
+        return ESP_FAIL;
+    }
+    return ESP_OK;
+}