From cb448280112f1b81fc2d94108e9f1674331f5636 Mon Sep 17 00:00:00 2001
From: Ueli Graf <ugraf@outlook.com>
Date: Thu, 26 Sep 2024 16:05:03 +0200
Subject: [PATCH 1/2] out_influxdb: allow stripping of tag prefix

Removes a configured prefix from measurement names

Signed-off-by: Ueli Graf <ugraf@outlook.com>
---
 plugins/out_influxdb/influxdb.c | 27 ++++++++++++++++++++++++++-
 plugins/out_influxdb/influxdb.h |  4 ++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/plugins/out_influxdb/influxdb.c b/plugins/out_influxdb/influxdb.c
index 671dd5c16a6..4e881284a97 100644
--- a/plugins/out_influxdb/influxdb.c
+++ b/plugins/out_influxdb/influxdb.c
@@ -74,6 +74,8 @@ static int influxdb_format(struct flb_config *config,
     char *str = NULL;
     size_t str_size;
     char tmp[128];
+    int prefix_match = 0;
+    int prefix_offset = 0;
     msgpack_object map;
     struct flb_time tm;
     struct influxdb_bulk *bulk = NULL;
@@ -124,8 +126,16 @@ static int influxdb_format(struct flb_config *config,
             ctx->seq++;
         }
 
+        prefix_match = strncmp(tag, ctx->prefix, ctx->prefix_len);
+        if (prefix_match == 0) {
+            if (tag_len > ctx->prefix_len) {
+                prefix_offset = ctx->prefix_len;
+            }
+        }
+
         ret = influxdb_bulk_append_header(bulk_head,
-                                          tag, tag_len,
+                                          tag + prefix_offset,
+                                          tag_len - prefix_offset,
                                           seq,
                                           ctx->seq_name, ctx->seq_len);
         if (ret == -1) {
@@ -368,6 +378,15 @@ static int cb_influxdb_init(struct flb_output_instance *ins, struct flb_config *
     }
     ctx->seq_len = strlen(ctx->seq_name);
 
+    /* prefix */
+    tmp = flb_output_get_property("strip_prefix", ins);
+    if (!tmp) {
+        ctx->prefix = flb_strdup("");
+    } else {
+        ctx->prefix = flb_strdup(tmp);
+    }
+    ctx->prefix_len = strlen(ctx->prefix);
+
     if (ctx->custom_uri) {
         /* custom URI endpoint (e.g: Grafana */
         if (ctx->custom_uri[0] != '/') {
@@ -696,6 +715,12 @@ static struct flb_config_map config_map[] = {
      "Use influxdb line protocol's integer type suffix."
     },
 
+    {
+     FLB_CONFIG_MAP_STR, "strip_prefix", NULL,
+     0, FLB_FALSE, 0,
+     "Prefix to be removed from the record tag when writing influx measurements."
+    },
+
     /* EOF */
     {0}
 };
diff --git a/plugins/out_influxdb/influxdb.h b/plugins/out_influxdb/influxdb.h
index c21145611c8..c6cc54e57d3 100644
--- a/plugins/out_influxdb/influxdb.h
+++ b/plugins/out_influxdb/influxdb.h
@@ -56,6 +56,10 @@ struct flb_influxdb {
     char *seq_name;
     int seq_len;
 
+    /* prefix */
+    char *prefix;
+    int prefix_len;
+
     /* auto_tags: on/off */
     int auto_tags;
 

From c45887d9476b99ee7e6c82ebb46abfb41d3b8a05 Mon Sep 17 00:00:00 2001
From: Ueli Graf <ugraf@outlook.com>
Date: Mon, 30 Sep 2024 08:39:51 +0000
Subject: [PATCH 2/2] out_influxdb properly free configuration string value on
 exit

Signed-off-by: Ueli Graf <ugraf@outlook.com>
---
 plugins/out_influxdb/influxdb.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/plugins/out_influxdb/influxdb.c b/plugins/out_influxdb/influxdb.c
index 4e881284a97..2205ee06096 100644
--- a/plugins/out_influxdb/influxdb.c
+++ b/plugins/out_influxdb/influxdb.c
@@ -613,6 +613,10 @@ static int cb_influxdb_exit(void *data, struct flb_config *config)
         flb_free(ctx->seq_name);
     }
 
+    if (ctx->prefix) {
+        flb_free(ctx->prefix);
+    }
+
     flb_upstream_destroy(ctx->u);
     flb_free(ctx);