plugins: out_azure_blob: add support for logging a specific key

Signed-off-by: Tomasz Wilk <[email protected]>

Author: tomekwilk

plugins/out_azure_blob/azure_blob.c

@@ -31,6 +31,8 @@
 #include <fluent-bit/flb_plugin.h>
 #include <fluent-bit/flb_notification.h>
 #include <fluent-bit/flb_scheduler.h>
+#include <fluent-bit/flb_record_accessor.h>
+#include <fluent-bit/flb_ra_key.h>
 
 #include <msgpack.h>
 
@@ -53,6 +55,113 @@ struct worker_info {
 
 FLB_TLS_DEFINE(struct worker_info, worker_info);
 
+static flb_sds_t cb_azb_msgpack_extract_log_key(void *out_context, const char *data,
+                                                uint64_t bytes)
+{
+    struct flb_azure_blob *ctx = out_context;
+    flb_sds_t out_buf = NULL;
+    msgpack_unpacked result;
+    msgpack_object root;
+    msgpack_object map;
+    struct flb_record_accessor *ra = NULL;
+    struct flb_ra_value *rval = NULL;
+    size_t off = 0;
+
+    ra = flb_ra_create(ctx->log_key, FLB_FALSE);
+    if (!ra) {
+        flb_plg_error(ctx->ins, "invalid record accessor pattern '%s'", ctx->log_key);
+        flb_errno();
+        return NULL;
+    }
+
+    /* Unpack the data */
+    msgpack_unpacked_init(&result);
+    while (1) {
+        msgpack_unpack_return ret = msgpack_unpack_next(&result, data, bytes, &off);
+        if (ret == MSGPACK_UNPACK_SUCCESS) {
+            root = result.data;
+            if (root.type != MSGPACK_OBJECT_ARRAY) {
+                continue;
+            }
+
+            if (root.via.array.size < 2) {
+                flb_plg_debug(ctx->ins, "msgpack array has insufficient elements");
+                continue;
+            }
+
+            map = root.via.array.ptr[1];
+
+            /* Get value using record accessor */
+            rval = flb_ra_get_value_object(ra, map);
+            if (!rval) {
+                flb_plg_error(ctx->ins, "could not find field '%s'", ctx->log_key);
+                continue;
+            }
+
+            /* Convert value based on its type */
+            if (rval->type == FLB_RA_STRING) {
+                out_buf = flb_sds_create_size(rval->o.via.str.size + 1);
+                if (out_buf) {
+                    flb_sds_copy(out_buf, rval->o.via.str.ptr, rval->o.via.str.size);
+                    flb_sds_cat(out_buf, "\n", 1);
+                }
+            }
+            else if (rval->type == FLB_RA_FLOAT) {
+                out_buf = flb_sds_create_size(64);
+                if (out_buf) {
+                    flb_sds_printf(&out_buf, "%f\n", rval->val.f64);
+                }
+            }
+            else if (rval->type == FLB_RA_INT) {
+                out_buf = flb_sds_create_size(64);
+                if (out_buf) {
+                    flb_sds_printf(&out_buf, "%" PRId64 "\n", rval->val.i64);
+                }
+            }
+            else {
+                flb_errno();
+                flb_plg_error(ctx->ins, "cannot convert given value for field '%s'", ctx->log_key);
+                flb_ra_key_value_destroy(rval);
+                rval = NULL;
+                break;
+            }
+
+            /* Check if buffer allocation succeeded */
+            if (!out_buf) {
+                flb_errno();
+                flb_plg_error(ctx->ins, "could not allocate output buffer");
+            }
+
+            flb_ra_key_value_destroy(rval);
+            rval = NULL;
+
+            /* Successfully found and processed log_key, exit loop */
+            break;
+        }
+        else if (ret == MSGPACK_UNPACK_CONTINUE) {
+            /* Buffer exhausted or truncated data, stop processing */
+            flb_plg_debug(ctx->ins, "msgpack unpack needs more data or data truncated");
+            break;
+        }
+        else if (ret == MSGPACK_UNPACK_PARSE_ERROR) {
+            flb_errno();
+            flb_plg_error(ctx->ins, "msgpack parse error");
+            break;
+        }
+        else {
+            flb_errno();
+            flb_plg_error(ctx->ins, "unexpected msgpack unpack return code %d", ret);
+            break;
+        }
+    }
+
+    /* Clean up */
+    msgpack_unpacked_destroy(&result);
+    flb_ra_destroy(ra);
+
+    return out_buf;
+}
+
 static int azure_blob_format(struct flb_config *config,
                              struct flb_input_instance *ins,
                              void *plugin_context,
@@ -65,11 +174,16 @@ static int azure_blob_format(struct flb_config *config,
     flb_sds_t out_buf;
     struct flb_azure_blob *ctx = plugin_context;
 
-    out_buf = flb_pack_msgpack_to_json_format(data, bytes,
-                                              FLB_PACK_JSON_FORMAT_LINES,
-                                              FLB_PACK_JSON_DATE_ISO8601,
-                                              ctx->date_key,
-                                              config->json_escape_unicode);
+    if (ctx->log_key) {
+        out_buf = cb_azb_msgpack_extract_log_key(ctx, data, bytes);
+    }
+    else {
+        out_buf = flb_pack_msgpack_to_json_format(data, bytes,
+                                                FLB_PACK_JSON_FORMAT_LINES,
+                                                FLB_PACK_JSON_DATE_ISO8601,
+                                                ctx->date_key,
+                                                config->json_escape_unicode);
+    }
     if (!out_buf) {
         return -1;
     }
@@ -713,7 +827,7 @@ static int ensure_container(struct flb_azure_blob *ctx)
                       ctx->container_name);
         return FLB_FALSE;
     }
-    
+
     flb_plg_error(ctx->ins, "get container request failed, status=%i",
                   status);
 
@@ -1780,6 +1894,14 @@ static struct flb_config_map config_map[] = {
      "Set the block type: appendblob or blockblob"
     },
 
+    {
+     FLB_CONFIG_MAP_STR, "log_key", NULL,
+     0, FLB_TRUE, offsetof(struct flb_azure_blob, log_key),
+     "By default, the whole log record will be sent to blob storage. "
+     "If you specify a key name with this option, then only the value of "
+     "that key will be sent"
+    },
+
     {
      FLB_CONFIG_MAP_STR, "compress", NULL,
      0, FLB_FALSE, 0,
@@ -1939,7 +2061,7 @@ static struct flb_config_map config_map[] = {
      "Whether to delete the buffered file early after successful blob creation. Default is false"
     },
 
-    { 
+    {
      FLB_CONFIG_MAP_INT, "blob_uri_length", "64",
      0, FLB_TRUE, offsetof(struct flb_azure_blob, blob_uri_length),
      "Set the length of generated blob uri before ingesting to Azure Kusto. Default is 64"

plugins/out_azure_blob/azure_blob.h

@@ -59,6 +59,7 @@ struct flb_azure_blob {
     flb_sds_t account_name;
     flb_sds_t container_name;
     flb_sds_t blob_type;
+    flb_sds_t log_key;
     flb_sds_t shared_key;
     flb_sds_t endpoint;
     flb_sds_t path;