fluent · nberlee · Nov 21, 2025
@@ -24,6 +24,8 @@
 #include <fluent-bit/flb_pack.h>
 #include <fluent-bit/flb_config_map.h>
 #include <fluent-bit/flb_gzip.h>
+#include <fluent-bit/flb_compression.h>
+#include <fluent-bit/flb_zstd.h>
 #include <fluent-bit/flb_base64.h>
 #include <fluent-bit/flb_sqldb.h>
 #include <fluent-bit/flb_input_blob.h>
@@ -136,7 +138,7 @@ static int construct_request_buffer(struct flb_azure_blob *ctx, flb_sds_t new_da
         }
         body = buffered_data = tmp;
         memcpy(body + buffer_size, new_data, flb_sds_len(new_data));
-        if (ctx->compress_gzip == FLB_FALSE){
+        if (ctx->compression == FLB_COMPRESSION_ALGORITHM_NONE) {
             body[body_size] = '\0';
         }
     }
@@ -149,6 +151,38 @@ static int construct_request_buffer(struct flb_azure_blob *ctx, flb_sds_t new_da
     return 0;
 }
 
+/*
+ * Compress a payload using the configured algorithm. Returns 0 on success and
+ * negative on failure so callers can gracefully fall back to sending the raw
+ * payload.
+ */
+static int azure_blob_compress_payload(int algorithm,
+                                       void *in_data, size_t in_len,
+                                       void **out_data, size_t *out_len)
+{
+    if (algorithm == FLB_COMPRESSION_ALGORITHM_GZIP) {
+        return flb_gzip_compress(in_data, in_len, out_data, out_len);
+    }
+    else if (algorithm == FLB_COMPRESSION_ALGORITHM_ZSTD) {
+        return flb_zstd_compress(in_data, in_len, out_data, out_len);
+    }
+
+    return -1;
+}
+
+/* Map a compression algorithm to its human-friendly label for logs. */
+static const char *azure_blob_compression_name(int algorithm)
+{
+    if (algorithm == FLB_COMPRESSION_ALGORITHM_GZIP) {
+        return "gzip";
+    }
+    else if (algorithm == FLB_COMPRESSION_ALGORITHM_ZSTD) {
+        return "zstd";
+    }
+
+    return "unknown";
+}
+
 void generate_random_string_blob(char *str, size_t length)
 {
     const char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
@@ -332,8 +366,12 @@ static int http_send_blob(struct flb_config *config, struct flb_azure_blob *ctx,
 {
     int ret;
     int compressed = FLB_FALSE;
-    int content_encoding = FLB_FALSE;
-    int content_type = FLB_FALSE;
+    int content_encoding = AZURE_BLOB_CE_NONE;
+    int content_type = AZURE_BLOB_CT_NONE;
+    int compression_algorithm = FLB_COMPRESSION_ALGORITHM_NONE;
+    int network_compression_algorithm = ctx->compression;
+    int network_compression_applied = FLB_FALSE;
+    int blob_compression_applied = FLB_FALSE;
     size_t b_sent;
     void *payload_buf;
     size_t payload_size;
@@ -358,27 +396,62 @@ static int http_send_blob(struct flb_config *config, struct flb_azure_blob *ctx,
     payload_buf = data;
     payload_size = bytes;
 
+    /* Determine compression algorithm */
+    if (network_compression_algorithm != FLB_COMPRESSION_ALGORITHM_NONE) {
+        compression_algorithm = network_compression_algorithm;
+    }
+
+    if (ctx->compress_blob == FLB_TRUE) {
+        if (compression_algorithm == FLB_COMPRESSION_ALGORITHM_NONE) {
+            compression_algorithm = FLB_COMPRESSION_ALGORITHM_GZIP;
+        }
+    }
+
     /* Handle compression requests */
-    if (ctx->compress_gzip == FLB_TRUE || ctx->compress_blob == FLB_TRUE) {
-        ret = flb_gzip_compress((void *) data, bytes, &payload_buf, &payload_size);
+    if (compression_algorithm != FLB_COMPRESSION_ALGORITHM_NONE) {
+        ret = azure_blob_compress_payload(compression_algorithm,
+                                          (void *) data, bytes,
+                                          &payload_buf, &payload_size);
         if (ret == 0) {
             compressed = FLB_TRUE;
+            if (network_compression_algorithm != FLB_COMPRESSION_ALGORITHM_NONE) {
+                network_compression_applied = FLB_TRUE;
+            }
+            if (ctx->compress_blob == FLB_TRUE) {
+                blob_compression_applied = FLB_TRUE;
+            }
         }
         else {
+            const char *alg_name;
+
+            alg_name = azure_blob_compression_name(compression_algorithm);
             flb_plg_warn(ctx->ins,
-                        "cannot gzip payload, disabling compression");
+                        "cannot %s payload, disabling compression",
+                        alg_name);
             payload_buf = data;
             payload_size = bytes;
+            compression_algorithm = FLB_COMPRESSION_ALGORITHM_NONE;
         }
     }
 
     /* set http header flags */
-    if (ctx->compress_blob == FLB_TRUE) {
+    if (blob_compression_applied == FLB_TRUE) {
         content_encoding = AZURE_BLOB_CE_NONE;
-        content_type = AZURE_BLOB_CT_GZIP;
+
+        if (compression_algorithm == FLB_COMPRESSION_ALGORITHM_ZSTD) {
+            content_type = AZURE_BLOB_CT_ZSTD;
+        }
+        else {
+            content_type = AZURE_BLOB_CT_GZIP;
+        }
     }
-    else if (compressed == FLB_TRUE) {
-        content_encoding = AZURE_BLOB_CE_GZIP;
+    else if (network_compression_applied == FLB_TRUE) {
+        if (network_compression_algorithm == FLB_COMPRESSION_ALGORITHM_GZIP) {
+            content_encoding = AZURE_BLOB_CE_GZIP;
+        }
+        else if (network_compression_algorithm == FLB_COMPRESSION_ALGORITHM_ZSTD) {
+            content_encoding = AZURE_BLOB_CE_ZSTD;
+        }
         content_type = AZURE_BLOB_CT_JSON;
     }
 
@@ -1783,14 +1856,15 @@ static struct flb_config_map config_map[] = {
     {
      FLB_CONFIG_MAP_STR, "compress", NULL,
      0, FLB_FALSE, 0,
-     "Set payload compression in network transfer. Option available is 'gzip'"
+        "Set payload compression in network transfer. Options: 'gzip', 'zstd'"
     },
 
     {
      FLB_CONFIG_MAP_BOOL, "compress_blob", "false",
      0, FLB_TRUE, offsetof(struct flb_azure_blob, compress_blob),
-     "Enable block blob GZIP compression in the final blob file. This option is "
-     "not compatible with 'appendblob' block type"
+        "Enable block blob compression in the final blob file (defaults to gzip, "
+        "uses the 'compress' codec when set). This option is not compatible with "
+        "'appendblob' block type"
     },
 
     {

@@ -30,11 +30,13 @@
 #define AZURE_BLOB_CT_NONE     0
 #define AZURE_BLOB_CT_JSON     1 /* application/json */
 #define AZURE_BLOB_CT_GZIP     2 /* application/gzip */
+#define AZURE_BLOB_CT_ZSTD     3 /* application/zstd */
 
 /* Content-Encoding */
 #define AZURE_BLOB_CE          "Content-Encoding"
 #define AZURE_BLOB_CE_NONE     0
 #define AZURE_BLOB_CE_GZIP     1 /* gzip */
+#define AZURE_BLOB_CE_ZSTD     2 /* zstd */
 
 /* service endpoint */
 #define AZURE_ENDPOINT_PREFIX  ".blob.core.windows.net"
@@ -54,7 +56,7 @@
 struct flb_azure_blob {
     int auto_create_container;
     int emulator_mode;
-    int compress_gzip;
+    int compression;
     int compress_blob;
     flb_sds_t account_name;
     flb_sds_t container_name;

@@ -23,6 +23,7 @@
 #include <fluent-bit/flb_sds.h>
 #include <fluent-bit/flb_hash.h>
 #include <fluent-bit/flb_crypto_constants.h>
+#include <fluent-bit/flb_compression.h>
 
 #include <math.h>
 
@@ -31,6 +32,19 @@
 #include "azure_blob_uri.h"
 #include "azure_blob_http.h"
 
+static const char *azb_blob_extension(struct flb_azure_blob *ctx)
+{
+    if (ctx->compress_blob != FLB_TRUE) {
+        return "";
+    }
+
+    if (ctx->compression == FLB_COMPRESSION_ALGORITHM_ZSTD) {
+        return ".zst";
+    }
+
+    return ".gz";
+}
+
 flb_sds_t azb_block_blob_blocklist_uri(struct flb_azure_blob *ctx, char *name)
 {
     flb_sds_t uri;
@@ -60,7 +74,7 @@ flb_sds_t azb_block_blob_uri(struct flb_azure_blob *ctx, char *name,
 {
     int len;
     flb_sds_t uri;
-    char *ext;
+    const char *ext;
     char *encoded_blockid;
 
     len = strlen(blockid);
@@ -75,12 +89,7 @@ flb_sds_t azb_block_blob_uri(struct flb_azure_blob *ctx, char *name,
         return NULL;
     }
 
-    if (ctx->compress_blob == FLB_TRUE) {
-        ext = ".gz";
-    }
-    else {
-        ext = "";
-    }
+    ext = azb_blob_extension(ctx);
 
     if (ctx->path) {
         if (ms > 0) {
@@ -114,20 +123,15 @@ flb_sds_t azb_block_blob_uri(struct flb_azure_blob *ctx, char *name,
 flb_sds_t azb_block_blob_uri_commit(struct flb_azure_blob *ctx,
                                     char *tag, uint64_t ms, char *str)
 {
-    char *ext;
+    const char *ext;
     flb_sds_t uri;
 
     uri = azb_uri_container(ctx);
     if (!uri) {
         return NULL;
     }
 
-    if (ctx->compress_blob == FLB_TRUE) {
-        ext = ".gz";
-    }
-    else {
-        ext = "";
-    }
+    ext = azb_blob_extension(ctx);
 
     if (ctx->path) {
         flb_sds_printf(&uri, "/%s/%s.%s.%" PRIu64 "%s?comp=blocklist", ctx->path, tag, str,

@@ -20,6 +20,7 @@
 #include <fluent-bit/flb_output_plugin.h>
 #include <fluent-bit/flb_base64.h>
 #include <fluent-bit/flb_pack.h>
+#include <fluent-bit/flb_compression.h>
 
 #include "azure_blob.h"
 #include "azure_blob_conf.h"
@@ -655,12 +656,19 @@ struct flb_azure_blob *flb_azure_blob_conf_create(struct flb_output_instance *in
         return NULL;
     }
 
-    /* Compress (gzip) */
+    /* Compress payload over the wire */
     tmp = (char *) flb_output_get_property("compress", ins);
-    ctx->compress_gzip = FLB_FALSE;
+    ctx->compression = FLB_COMPRESSION_ALGORITHM_NONE;
     if (tmp) {
         if (strcasecmp(tmp, "gzip") == 0) {
-            ctx->compress_gzip = FLB_TRUE;
+            ctx->compression = FLB_COMPRESSION_ALGORITHM_GZIP;
+        }
+        else if (strcasecmp(tmp, "zstd") == 0) {
+            ctx->compression = FLB_COMPRESSION_ALGORITHM_ZSTD;
+        }
+        else {
+            flb_plg_error(ctx->ins, "invalid compress value '%s' (supported: gzip, zstd)", tmp);
+            return NULL;
         }
     }
 

@@ -193,6 +193,9 @@ flb_sds_t azb_http_canonical_request(struct flb_azure_blob *ctx,
     if (content_encoding == AZURE_BLOB_CE_GZIP) {
         encoding = "gzip";
     }
+    else if (content_encoding == AZURE_BLOB_CE_ZSTD) {
+        encoding = "zstd";
+    }
     else {
         encoding = "";
     }
@@ -223,6 +226,9 @@ flb_sds_t azb_http_canonical_request(struct flb_azure_blob *ctx,
     else if (content_type == AZURE_BLOB_CT_GZIP) {
         ctype = "application/gzip";
     }
+    else if (content_type == AZURE_BLOB_CT_ZSTD) {
+        ctype = "application/zstd";
+    }
 
     flb_sds_printf(&can_req,
                    "\n"    /* Content-MD5 */
@@ -315,12 +321,22 @@ int azb_http_client_setup(struct flb_azure_blob *ctx, struct flb_http_client *c,
                             AZURE_BLOB_CT, sizeof(AZURE_BLOB_CT) - 1,
                             "application/gzip", 16);
     }
+    else if (content_type == AZURE_BLOB_CT_ZSTD) {
+        flb_http_add_header(c,
+                            AZURE_BLOB_CT, sizeof(AZURE_BLOB_CT) - 1,
+                            "application/zstd", 16);
+    }
 
     if (content_encoding == AZURE_BLOB_CE_GZIP) {
         flb_http_add_header(c,
                             AZURE_BLOB_CE, sizeof(AZURE_BLOB_CE) - 1,
                             "gzip", 4);
     }
+    else if (content_encoding == AZURE_BLOB_CE_ZSTD) {
+        flb_http_add_header(c,
+                            AZURE_BLOB_CE, sizeof(AZURE_BLOB_CE) - 1,
+                            "zstd", 4);
+    }
 
     /* Azure header: x-ms-blob-type */
     if (blob_type == FLB_TRUE) {

@@ -31,6 +31,7 @@ int azb_http_client_setup(struct flb_azure_blob *ctx, struct flb_http_client *c,
 flb_sds_t azb_http_canonical_request(struct flb_azure_blob *ctx,
                                      struct flb_http_client *c,
                                      ssize_t content_length,
-                                     int content_type);
+                                     int content_type,
+                                     int content_encoding);
 
 #endif
@@ -18,6 +18,7 @@ set(UNIT_TESTS_FILES
   unit_sizes.c
   hashtable.c
   http_client.c
+  azure_blob.c
   utils.c
   gzip.c
   zstd.c