Add a Prometheus Remote Write connector to the exporting engine (#8292)

* Copy files from the Prometheus remote write backend

* Update the documentation

* Rename backend -> exporting

* Add the connector to the Netdata build

* Separate files for the remote write connector

* Add an initializer and formatters

* Read a connector specific configuration option

* Add a separate function for header sending

* Use labels instead of tags

* Separate write request for every instance

* Add unit tests

6 files changed, 88 insertions, 89 deletions

diff --git a/backends/backends.c b/backends/backends.c
index b373b2d05e..e1964bd4a2 100644
--- a/backends/backends.c
+++ b/backends/backends.c
@@ -295,7 +295,7 @@ void backend_set_prometheus_variables(int *default_port,
 #endif
 
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
-    *brc = process_prometheus_remote_write_response;
+    *brc = backends_process_prometheus_remote_write_response;
 #endif /* ENABLE_PROMETHEUS_REMOTE_WRITE */
 }
 
@@ -439,7 +439,7 @@ BACKEND_TYPE backend_select_type(const char *type) {
         return BACKEND_TYPE_JSON;
     }
     else if (!strcmp(type, "prometheus_remote_write")) {
-        return  BACKEND_TYPE_PROMETHEUS;
+        return  BACKEND_TYPE_PROMETHEUS_REMOTE_WRITE;
     }
     else if (!strcmp(type, "kinesis") || !strcmp(type, "kinesis:plaintext")) {
         return BACKEND_TYPE_KINESIS;
@@ -557,12 +557,12 @@ void *backends_main(void *ptr) {
             backend_set_opentsdb_http_variables(&default_port,&backend_response_checker,&backend_request_formatter);
             break;
         }
-        case BACKEND_TYPE_PROMETHEUS: {
+        case BACKEND_TYPE_PROMETHEUS_REMOTE_WRITE: {
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
             do_prometheus_remote_write = 1;
 
             http_request_header = buffer_create(1);
-            init_write_request();
+            backends_init_write_request();
 #else
             error("BACKEND: Prometheus remote write support isn't compiled");
 #endif // ENABLE_PROMETHEUS_REMOTE_WRITE
@@ -724,7 +724,7 @@ void *backends_main(void *ptr) {
 
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
         if(do_prometheus_remote_write)
-            clear_write_request();
+            backends_clear_write_request();
 #endif
         rrd_rdlock();
         RRDHOST *host;
@@ -755,7 +755,7 @@ void *backends_main(void *ptr) {
 
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
             if(do_prometheus_remote_write) {
-                rrd_stats_remote_write_allmetrics_prometheus(
+                backends_rrd_stats_remote_write_allmetrics_prometheus(
                     host
                     , __hostname
                     , global_backend_prefix
@@ -1048,7 +1048,7 @@ void *backends_main(void *ptr) {
 
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
                 if(do_prometheus_remote_write) {
-                    size_t data_size = get_write_request_size();
+                    size_t data_size = backends_get_write_request_size();
 
                     if(unlikely(!data_size)) {
                         error("BACKEND: write request size is out of range");
@@ -1057,7 +1057,7 @@ void *backends_main(void *ptr) {
 
                     buffer_flush(b);
                     buffer_need_bytes(b, data_size);
-                    if(unlikely(pack_write_request(b->buffer, &data_size))) {
+                    if(unlikely(backends_pack_write_request(b->buffer, &data_size))) {
                         error("BACKEND: cannot pack write request");
                         continue;
                     }
@@ -1137,7 +1137,7 @@ void *backends_main(void *ptr) {
         if(do_prometheus_remote_write && failures) {
             (void) buffer_on_failures;
             failures = 0;
-            chart_lost_bytes = chart_buffered_bytes = get_write_request_size(); // estimated write request size
+            chart_lost_bytes = chart_buffered_bytes = backends_get_write_request_size(); // estimated write request size
             chart_data_lost_events++;
             chart_lost_metrics = chart_buffered_metrics;
         } else
@@ -1209,7 +1209,7 @@ cleanup:
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
     buffer_free(http_request_header);
     if(do_prometheus_remote_write)
-        protocol_buffers_shutdown();
+        backends_protocol_buffers_shutdown();
 #endif
 
 #if HAVE_MONGOC
diff --git a/backends/backends.h b/backends/backends.h
index c0cd235987..212823a078 100644
--- a/backends/backends.h
+++ b/backends/backends.h
@@ -21,7 +21,7 @@ typedef enum backend_types {
     BACKEND_TYPE_OPENTSDB_USING_TELNET,     // Send data to OpenTSDB using telnet API
     BACKEND_TYPE_OPENTSDB_USING_HTTP,       // Send data to OpenTSDB using HTTP API
     BACKEND_TYPE_JSON,                      // Stores the data using JSON.
-    BACKEND_TYPE_PROMETHEUS,                // The user selected to use Prometheus backend
+    BACKEND_TYPE_PROMETHEUS_REMOTE_WRITE,   // The user selected to use Prometheus backend
     BACKEND_TYPE_KINESIS,                   // Send message to AWS Kinesis
     BACKEND_TYPE_MONGODB,                   // Send data to MongoDB collection
     BACKEND_TYPE_NUM                        // Number of backend types
diff --git a/backends/prometheus/backend_prometheus.c b/backends/prometheus/backend_prometheus.c
index 2db911621d..b3f955e15f 100644
--- a/backends/prometheus/backend_prometheus.c
+++ b/backends/prometheus/backend_prometheus.c
@@ -159,7 +159,7 @@ struct host_variables_callback_options {
     RRDHOST *host;
     BUFFER *wb;
     BACKEND_OPTIONS backend_options;
-    PROMETHEUS_OUTPUT_OPTIONS output_options;
+    BACKENDS_PROMETHEUS_OUTPUT_OPTIONS output_options;
     const char *prefix;
     const char *labels;
     time_t now;
@@ -174,14 +174,14 @@ static int print_host_variables(RRDVAR *rv, void *data) {
         if(!opts->host_header_printed) {
             opts->host_header_printed = 1;
 
-            if(opts->output_options & PROMETHEUS_OUTPUT_HELP) {
+            if(opts->output_options & BACKENDS_PROMETHEUS_OUTPUT_HELP) {
                 buffer_sprintf(opts->wb, "\n# COMMENT global host and chart variables\n");
             }
         }
 
         calculated_number value = rrdvar2number(rv);
         if(isnan(value) || isinf(value)) {
-            if(opts->output_options & PROMETHEUS_OUTPUT_HELP)
+            if(opts->output_options & BACKENDS_PROMETHEUS_OUTPUT_HELP)
                 buffer_sprintf(opts->wb, "# COMMENT variable \"%s\" is %s. Skipped.\n", rv->name, (isnan(value))?"NAN":"INF");
 
             return 0;
@@ -196,7 +196,7 @@ static int print_host_variables(RRDVAR *rv, void *data) {
 
         prometheus_name_copy(opts->name, rv->name, sizeof(opts->name));
 
-        if(opts->output_options & PROMETHEUS_OUTPUT_TIMESTAMPS)
+        if(opts->output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS)
             buffer_sprintf(opts->wb
                            , "%s_%s%s%s%s " CALCULATED_NUMBER_FORMAT " %llu\n"
                            , opts->prefix
@@ -223,7 +223,7 @@ static int print_host_variables(RRDVAR *rv, void *data) {
     return 0;
 }
 
-static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER *wb, const char *prefix, BACKEND_OPTIONS backend_options, time_t after, time_t before, int allhosts, PROMETHEUS_OUTPUT_OPTIONS output_options) {
+static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER *wb, const char *prefix, BACKEND_OPTIONS backend_options, time_t after, time_t before, int allhosts, BACKENDS_PROMETHEUS_OUTPUT_OPTIONS output_options) {
     rrdhost_rdlock(host);
 
     char hostname[PROMETHEUS_ELEMENT_MAX + 1];
@@ -231,13 +231,13 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
 
     char labels[PROMETHEUS_LABELS_MAX + 1] = "";
     if(allhosts) {
-        if(output_options & PROMETHEUS_OUTPUT_TIMESTAMPS)
+        if(output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS)
             buffer_sprintf(wb, "netdata_info{instance=\"%s\",application=\"%s\",version=\"%s\"} 1 %llu\n", hostname, host->program_name, host->program_version, now_realtime_usec() / USEC_PER_MS);
         else
             buffer_sprintf(wb, "netdata_info{instance=\"%s\",application=\"%s\",version=\"%s\"} 1\n", hostname, host->program_name, host->program_version);
 
         if(host->tags && *(host->tags)) {
-            if(output_options & PROMETHEUS_OUTPUT_TIMESTAMPS) {
+            if(output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS) {
                 buffer_sprintf(wb, "netdata_host_tags_info{instance=\"%s\",%s} 1 %llu\n", hostname, host->tags, now_realtime_usec() / USEC_PER_MS);
 
                 // deprecated, exists only for compatibility with older queries
@@ -255,13 +255,13 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
         snprintfz(labels, PROMETHEUS_LABELS_MAX, ",instance=\"%s\"", hostname);
     }
     else {
-        if(output_options & PROMETHEUS_OUTPUT_TIMESTAMPS)
+        if(output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS)
             buffer_sprintf(wb, "netdata_info{instance=\"%s\",application=\"%s\",version=\"%s\"} 1 %llu\n", hostname, host->program_name, host->program_version, now_realtime_usec() / USEC_PER_MS);
         else
             buffer_sprintf(wb, "netdata_info{instance=\"%s\",application=\"%s\",version=\"%s\"} 1\n", hostname, host->program_name, host->program_version);
 
         if(host->tags && *(host->tags)) {
-            if(output_options & PROMETHEUS_OUTPUT_TIMESTAMPS) {
+            if(output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS) {
                 buffer_sprintf(wb, "netdata_host_tags_info{%s} 1 %llu\n", host->tags, now_realtime_usec() / USEC_PER_MS);
 
                 // deprecated, exists only for compatibility with older queries
@@ -277,7 +277,7 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
     }
 
     // send custom variables set for the host
-    if(output_options & PROMETHEUS_OUTPUT_VARIABLES){
+    if(output_options & BACKENDS_PROMETHEUS_OUTPUT_VARIABLES){
         struct host_variables_callback_options opts = {
                 .host = host,
                 .wb = wb,
@@ -299,7 +299,7 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
         char family[PROMETHEUS_ELEMENT_MAX + 1];
         char units[PROMETHEUS_ELEMENT_MAX + 1] = "";
 
-        prometheus_label_copy(chart, (output_options & PROMETHEUS_OUTPUT_NAMES && st->name)?st->name:st->id, PROMETHEUS_ELEMENT_MAX);
+        prometheus_label_copy(chart, (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && st->name)?st->name:st->id, PROMETHEUS_ELEMENT_MAX);
         prometheus_label_copy(family, st->family, PROMETHEUS_ELEMENT_MAX);
         prometheus_name_copy(context, st->context, PROMETHEUS_ELEMENT_MAX);
 
@@ -316,14 +316,14 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                     homogeneous = 0;
             }
             else {
-                if(BACKEND_OPTIONS_DATA_SOURCE(backend_options) == BACKEND_SOURCE_DATA_AVERAGE && !(output_options & PROMETHEUS_OUTPUT_HIDEUNITS))
-                    prometheus_units_copy(units, st->units, PROMETHEUS_ELEMENT_MAX, output_options & PROMETHEUS_OUTPUT_OLDUNITS);
+                if(BACKEND_OPTIONS_DATA_SOURCE(backend_options) == BACKEND_SOURCE_DATA_AVERAGE && !(output_options & BACKENDS_PROMETHEUS_OUTPUT_HIDEUNITS))
+                    prometheus_units_copy(units, st->units, PROMETHEUS_ELEMENT_MAX, output_options & BACKENDS_PROMETHEUS_OUTPUT_OLDUNITS);
             }
 
-            if(unlikely(output_options & PROMETHEUS_OUTPUT_HELP))
+            if(unlikely(output_options & BACKENDS_PROMETHEUS_OUTPUT_HELP))
                 buffer_sprintf(wb, "\n# COMMENT %s chart \"%s\", context \"%s\", family \"%s\", units \"%s\"\n"
                                , (homogeneous)?"homogeneous":"heterogeneous"
-                               , (output_options & PROMETHEUS_OUTPUT_NAMES && st->name) ? st->name : st->id
+                               , (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && st->name) ? st->name : st->id
                                , st->context
                                , st->family
                                , st->units
@@ -354,18 +354,18 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                             // all the dimensions of the chart, has the same algorithm, multiplier and divisor
                             // we add all dimensions as labels
 
-                            prometheus_label_copy(dimension, (output_options & PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
+                            prometheus_label_copy(dimension, (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
 
-                            if(unlikely(output_options & PROMETHEUS_OUTPUT_HELP))
+                            if(unlikely(output_options & BACKENDS_PROMETHEUS_OUTPUT_HELP))
                                 buffer_sprintf(wb
                                                , "# COMMENT %s_%s%s: chart \"%s\", context \"%s\", family \"%s\", dimension \"%s\", value * " COLLECTED_NUMBER_FORMAT " / " COLLECTED_NUMBER_FORMAT " %s %s (%s)\n"
                                                , prefix
                                                , context
                                                , suffix
-                                               , (output_options & PROMETHEUS_OUTPUT_NAMES && st->name) ? st->name : st->id
+                                               , (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && st->name) ? st->name : st->id
                                                , st->context
                                                , st->family
-                                               , (output_options & PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id
+                                               , (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id
                                                , rd->multiplier
                                                , rd->divisor
                                                , h
@@ -373,7 +373,7 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                                                , t
                                 );
 
-                            if(unlikely(output_options & PROMETHEUS_OUTPUT_TYPES))
+                            if(unlikely(output_options & BACKENDS_PROMETHEUS_OUTPUT_TYPES))
                                 buffer_sprintf(wb, "# COMMENT TYPE %s_%s%s %s\n"
                                                , prefix
                                                , context
@@ -381,7 +381,7 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                                                , t
                                 );
 
-                            if(output_options & PROMETHEUS_OUTPUT_TIMESTAMPS)
+                            if(output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS)
                                 buffer_sprintf(wb
                                                , "%s_%s%s{chart=\"%s\",family=\"%s\",dimension=\"%s\"%s} " COLLECTED_NUMBER_FORMAT " %llu\n"
                                                , prefix
@@ -411,19 +411,19 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                             // the dimensions of the chart, do not have the same algorithm, multiplier or divisor
                             // we create a metric per dimension
 
-                            prometheus_name_copy(dimension, (output_options & PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
+                            prometheus_name_copy(dimension, (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
 
-                            if(unlikely(output_options & PROMETHEUS_OUTPUT_HELP))
+                            if(unlikely(output_options & BACKENDS_PROMETHEUS_OUTPUT_HELP))
                                 buffer_sprintf(wb
                                                , "# COMMENT %s_%s_%s%s: chart \"%s\", context \"%s\", family \"%s\", dimension \"%s\", value * " COLLECTED_NUMBER_FORMAT " / " COLLECTED_NUMBER_FORMAT " %s %s (%s)\n"
                                                , prefix
                                                , context
                                                , dimension
                                                , suffix
-                                               , (output_options & PROMETHEUS_OUTPUT_NAMES && st->name) ? st->name : st->id
+                                               , (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && st->name) ? st->name : st->id
                                                , st->context
                                                , st->family
-                                               , (output_options & PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id
+                                               , (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id
                                                , rd->multiplier
                                                , rd->divisor
                                                , h
@@ -431,7 +431,7 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                                                , t
                                 );
 
-                            if(unlikely(output_options & PROMETHEUS_OUTPUT_TYPES))
+                            if(unlikely(output_options & BACKENDS_PROMETHEUS_OUTPUT_TYPES))
                                 buffer_sprintf(wb, "# COMMENT TYPE %s_%s_%s%s %s\n"
                                                , prefix
                                                , context
@@ -440,7 +440,7 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                                                , t
                                 );
 
-                            if(output_options & PROMETHEUS_OUTPUT_TIMESTAMPS)
+                            if(output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS)
                                 buffer_sprintf(wb
                                                , "%s_%s_%s%s{chart=\"%s\",family=\"%s\"%s} " COLLECTED_NUMBER_FORMAT " %llu\n"
                                                , prefix
@@ -480,21 +480,21 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                             else if(BACKEND_OPTIONS_DATA_SOURCE(backend_options) == BACKEND_SOURCE_DATA_SUM)
                                 suffix = "_sum";
 
-                            prometheus_label_copy(dimension, (output_options & PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
+                            prometheus_label_copy(dimension, (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
 
-                            if (unlikely(output_options & PROMETHEUS_OUTPUT_HELP))
+                            if (unlikely(output_options & BACKENDS_PROMETHEUS_OUTPUT_HELP))
                                 buffer_sprintf(wb, "# COMMENT %s_%s%s%s: dimension \"%s\", value is %s, gauge, dt %llu to %llu inclusive\n"
                                                , prefix
                                                , context
                                                , units
                                                , suffix
-                                               , (output_options & PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id
+                                               , (output_options & BACKENDS_PROMETHEUS_OUTPUT_NAMES && rd->name) ? rd->name : rd->id
                                                , st->units
                                                , (unsigned long long)first_t
                                                , (unsigned long long)last_t
                                 );
 
-                            if (unlikely(output_options & PROMETHEUS_OUTPUT_TYPES))
+                            if (unlikely(output_options & BACKENDS_PROMETHEUS_OUTPUT_TYPES))
                                 buffer_sprintf(wb, "# COMMENT TYPE %s_%s%s%s gauge\n"
                                                , prefix
                                                , context
@@ -502,7 +502,7 @@ static void rrd_stats_api_v1_charts_allmetrics_prometheus(RRDHOST *host, BUFFER
                                                , suffix
                                 );
 
-                            if(output_options & PROMETHEUS_OUTPUT_TIMESTAMPS)
+                            if(output_options & BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS)
                                 buffer_sprintf(wb, "%s_%s%s%s{chart=\"%s\",family=\"%s\",dimension=\"%s\"%s} " CALCULATED_NUMBER_FORMAT " %llu\n"
                                                , prefix
                                                , context
@@ -581,7 +581,7 @@ inline static void remote_write_split_words(char *str, char **words, int max_wor
     }
 }
 
-void rrd_stats_remote_write_allmetrics_prometheus(
+void backends_rrd_stats_remote_write_allmetrics_prometheus(
         RRDHOST *host
         , const char *__hostname
         , const char *prefix
@@ -595,7 +595,7 @@ void rrd_stats_remote_write_allmetrics_prometheus(
     char hostname[PROMETHEUS_ELEMENT_MAX + 1];
     prometheus_label_copy(hostname, __hostname, PROMETHEUS_ELEMENT_MAX);
 
-    add_host_info("netdata_info", hostname, host->program_name, host->program_version, now_realtime_usec() / USEC_PER_MS);
+    backends_add_host_info("netdata_info", hostname, host->program_name, host->program_version, now_realtime_usec() / USEC_PER_MS);
 
     if(host->tags && *(host->tags)) {
         char tags[PROMETHEUS_LABELS_MAX + 1];
@@ -605,10 +605,10 @@ void rrd_stats_remote_write_allmetrics_prometheus(
 
         remote_write_split_words(tags, words, PROMETHEUS_LABELS_MAX_NUMBER);
 
-        add_host_info("netdata_host_tags_info", hostname, NULL, NULL, now_realtime_usec() / USEC_PER_MS);
+        backends_add_host_info("netdata_host_tags_info", hostname, NULL, NULL, now_realtime_usec() / USEC_PER_MS);
 
         for(i = 0; words[i] != NULL && words[i + 1] != NULL && (i + 1) < PROMETHEUS_LABELS_MAX_NUMBER; i += 2) {
-            add_tag(words[i], words[i + 1]);
+            backends_add_tag(words[i], words[i + 1]);
         }
     }
 
@@ -667,7 +667,7 @@ void rrd_stats_remote_write_allmetrics_prometheus(
                             prometheus_label_copy(dimension, (backend_options & BACKEND_OPTION_SEND_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
                             snprintf(name, PROMETHEUS_LABELS_MAX, "%s_%s%s", prefix, context, suffix);
 
-                            add_metric(name, chart, family, dimension, hostname, rd->last_collected_value, timeval_msec(&rd->last_collected_time));
+                            backends_add_metric(name, chart, family, dimension, hostname, rd->last_collected_value, timeval_msec(&rd->last_collected_time));
                             (*count_dims)++;
                         }
                         else {
@@ -677,7 +677,7 @@ void rrd_stats_remote_write_allmetrics_prometheus(
                             prometheus_name_copy(dimension, (backend_options & BACKEND_OPTION_SEND_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
                             snprintf(name, PROMETHEUS_LABELS_MAX, "%s_%s_%s%s", prefix, context, dimension, suffix);
 
-                            add_metric(name, chart, family, NULL, hostname, rd->last_collected_value, timeval_msec(&rd->last_collected_time));
+                            backends_add_metric(name, chart, family, NULL, hostname, rd->last_collected_value, timeval_msec(&rd->last_collected_time));
                             (*count_dims)++;
                         }
                     }
@@ -697,7 +697,7 @@ void rrd_stats_remote_write_allmetrics_prometheus(
                             prometheus_label_copy(dimension, (backend_options & BACKEND_OPTION_SEND_NAMES && rd->name) ? rd->name : rd->id, PROMETHEUS_ELEMENT_MAX);
                             snprintf(name, PROMETHEUS_LABELS_MAX, "%s_%s%s%s", prefix, context, units, suffix);
 
-                            add_metric(name, chart, family, dimension, hostname, value, last_t * MSEC_PER_SEC);
+                            backends_add_metric(name, chart, family, dimension, hostname, value, last_t * MSEC_PER_SEC);
                             (*count_dims)++;
                         }
                     }
@@ -710,7 +710,7 @@ void rrd_stats_remote_write_allmetrics_prometheus(
 }
 #endif /* ENABLE_PROMETHEUS_REMOTE_WRITE */
 
-static inline time_t prometheus_preparation(RRDHOST *host, BUFFER *wb, BACKEND_OPTIONS backend_options, const char *server, time_t now, PROMETHEUS_OUTPUT_OPTIONS output_options) {
+static inline time_t prometheus_preparation(RRDHOST *host, BUFFER *wb, BACKEND_OPTIONS backend_options, const char *server, time_t now, BACKENDS_PROMETHEUS_OUTPUT_OPTIONS output_options) {
     if(!server || !*server) server = "default";
 
     time_t after  = prometheus_server_last_access(server, host, now);
@@ -726,7 +726,7 @@ static inline time_t prometheus_preparation(RRDHOST *host, BUFFER *wb, BACKEND_O
         after = now - global_backend_update_every;
     }
 
-    if(output_options & PROMETHEUS_OUTPUT_HELP) {
+    if(output_options & BACKENDS_PROMETHEUS_OUTPUT_HELP) {
         char *mode;
         if(BACKEND_OPTIONS_DATA_SOURCE(backend_options) == BACKEND_SOURCE_DATA_AS_COLLECTED)
             mode = "as collected";
@@ -751,7 +751,7 @@ static inline time_t prometheus_preparation(RRDHOST *host, BUFFER *wb, BACKEND_O
     return after;
 }
 
-void rrd_stats_api_v1_charts_allmetrics_prometheus_single_host(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, PROMETHEUS_OUTPUT_OPTIONS output_options) {
+void backends_rrd_stats_api_v1_charts_allmetrics_prometheus_single_host(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, BACKENDS_PROMETHEUS_OUTPUT_OPTIONS output_options) {
     time_t before = now_realtime_sec();
 
     // we start at the point we had stopped before
@@ -760,7 +760,7 @@ void rrd_stats_api_v1_charts_allmetrics_prometheus_single_host(RRDHOST *host, BU
     rrd_stats_api_v1_charts_allmetrics_prometheus(host, wb, prefix, backend_options, after, before, 0, output_options);
 }
 
-void rrd_stats_api_v1_charts_allmetrics_prometheus_all_hosts(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, PROMETHEUS_OUTPUT_OPTIONS output_options) {
+void backends_rrd_stats_api_v1_charts_allmetrics_prometheus_all_hosts(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, BACKENDS_PROMETHEUS_OUTPUT_OPTIONS output_options) {
     time_t before = now_realtime_sec();
 
     // we start at the point we had stopped before
@@ -774,7 +774,7 @@ void rrd_stats_api_v1_charts_allmetrics_prometheus_all_hosts(RRDHOST *host, BUFF
 }
 
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
-int process_prometheus_remote_write_response(BUFFER *b) {
+int backends_process_prometheus_remote_write_response(BUFFER *b) {
     if(unlikely(!b)) return 1;
 
     const char *s = buffer_tostring(b);
diff --git a/backends/prometheus/backend_prometheus.h b/backends/prometheus/backend_prometheus.h
index d58d24004b..8c14ddc26c 100644
--- a/backends/prometheus/backend_prometheus.h
+++ b/backends/prometheus/backend_prometheus.h
@@ -5,22 +5,22 @@
 
 #include "backends/backends.h"
 
-typedef enum prometheus_output_flags {
-    PROMETHEUS_OUTPUT_NONE       = 0,
-    PROMETHEUS_OUTPUT_HELP       = (1 << 0),
-    PROMETHEUS_OUTPUT_TYPES      = (1 << 1),
-    PROMETHEUS_OUTPUT_NAMES      = (1 << 2),
-    PROMETHEUS_OUTPUT_TIMESTAMPS = (1 << 3),
-    PROMETHEUS_OUTPUT_VARIABLES  = (1 << 4),
-	PROMETHEUS_OUTPUT_OLDUNITS   = (1 << 5),
-	PROMETHEUS_OUTPUT_HIDEUNITS  = (1 << 6)
-} PROMETHEUS_OUTPUT_OPTIONS;
+typedef enum backends_prometheus_output_flags {
+    BACKENDS_PROMETHEUS_OUTPUT_NONE       = 0,
+    BACKENDS_PROMETHEUS_OUTPUT_HELP       = (1 << 0),
+    BACKENDS_PROMETHEUS_OUTPUT_TYPES      = (1 << 1),
+    BACKENDS_PROMETHEUS_OUTPUT_NAMES      = (1 << 2),
+    BACKENDS_PROMETHEUS_OUTPUT_TIMESTAMPS = (1 << 3),
+    BACKENDS_PROMETHEUS_OUTPUT_VARIABLES  = (1 << 4),
+    BACKENDS_PROMETHEUS_OUTPUT_OLDUNITS   = (1 << 5),
+    BACKENDS_PROMETHEUS_OUTPUT_HIDEUNITS  = (1 << 6)
+} BACKENDS_PROMETHEUS_OUTPUT_OPTIONS;
 
-extern void rrd_stats_api_v1_charts_allmetrics_prometheus_single_host(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, PROMETHEUS_OUTPUT_OPTIONS output_options);
-extern void rrd_stats_api_v1_charts_allmetrics_prometheus_all_hosts(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, PROMETHEUS_OUTPUT_OPTIONS output_options);
+extern void backends_rrd_stats_api_v1_charts_allmetrics_prometheus_single_host(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, BACKENDS_PROMETHEUS_OUTPUT_OPTIONS output_options);
+extern void backends_rrd_stats_api_v1_charts_allmetrics_prometheus_all_hosts(RRDHOST *host, BUFFER *wb, const char *server, const char *prefix, BACKEND_OPTIONS backend_options, BACKENDS_PROMETHEUS_OUTPUT_OPTIONS output_options);
 
 #if ENABLE_PROMETHEUS_REMOTE_WRITE
-extern void rrd_stats_remote_write_allmetrics_prometheus(
+extern void backends_rrd_stats_remote_write_allmetrics_prometheus(
         RRDHOST *host
         , const char *__hostname
         , const char *prefix
@@ -31,7 +31,7 @@ extern void rrd_stats_remote_write_allmetrics_prometheus(
         , size_t *count_dims
         , size_t *count_dims_skipped
 );
-extern int process_prometheus_remote_write_response(BUFFER *b);
+extern int backends_process_prometheus_remote_write_response(BUFFER *b);
 #endif
 
 #endif //NETDATA_BACKEND_PROMETHEUS_H
diff --git a/backends/prometheus/remote_write/remote_write.cc b/backends/prometheus/remote_write/remote_write.cc
index 8246feefa6..d74e7d8be9 100644
--- a/backends/prometheus/remote_write/remote_write.cc
+++ b/backends/prometheus/remote_write/remote_write.cc
@@ -1,25 +1,24 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include <snappy.h>
-#include "remote_write.pb.h"
+#include "../../../exporting/prometheus/remote_write/remote_write.pb.h"
 #include "remote_write.h"
 
 using namespace prometheus;
 
+static google::protobuf::Arena arena;
+static WriteRequest *write_request;
 
-google::protobuf::Arena arena;
-WriteRequest *write_request;
-
-void init_write_request() {
+void backends_init_write_request() {
     GOOGLE_PROTOBUF_VERIFY_VERSION;
     write_request = google::protobuf::Arena::CreateMessage<WriteRequest>(&arena);
 }
 
-void clear_write_request() {
+void backends_clear_write_request() {
     write_request->clear_timeseries();
 }
 
-void add_host_info(const char *name, const char *instance, const char *application, const char *version, const int64_t timestamp) {
+void backends_add_host_info(const char *name, const char *instance, const char *application, const char *version, const int64_t timestamp) {
     TimeSeries *timeseries;
     Sample *sample;
     Label *label;
@@ -52,7 +51,7 @@ void add_host_info(const char *name, const char *instance, const char *applicati
 }
 
 // adds tag to the last created timeseries
-void add_tag(char *tag, char *value) {
+void backends_add_tag(char *tag, char *value) {
     TimeSeries *timeseries;
     Label *label;
 
@@ -63,7 +62,7 @@ void add_tag(char *tag, char *value) {
     label->set_value(value);
 }
 
-void add_metric(const char *name, const char *chart, const char *family, const char *dimension, const char *instance, const double value, const int64_t timestamp) {
+void backends_add_metric(const char *name, const char *chart, const char *family, const char *dimension, const char *instance, const double value, const int64_t timestamp) {
     TimeSeries *timeseries;
     Sample *sample;
     Label *label;
@@ -97,7 +96,7 @@ void add_metric(const char *name, const char *chart, const char *family, const c
     sample->set_timestamp(timestamp);
 }
 
-size_t get_write_request_size(){
+size_t backends_get_write_request_size(){
 #if GOOGLE_PROTOBUF_VERSION < 3001000
     size_t size = (size_t)snappy::MaxCompressedLength(write_request->ByteSize());
 #else
@@ -107,7 +106,7 @@ size_t get_write_request_size(){
     return (size < INT_MAX)?size:0;
 }
 
-int pack_write_request(char *buffer, size_t *size) {
+int backends_pack_write_request(char *buffer, size_t *size) {
     std::string uncompressed_write_request;
     if(write_request->SerializeToString(&uncompressed_write_request) == false) return 1;
 
@@ -116,6 +115,6 @@ int pack_write_request(char *buffer, size_t *size) {
     return 0;
 }
 
-void protocol_buffers_shutdown() {
+void backends_protocol_buffers_shutdown() {
     google::protobuf::ShutdownProtobufLibrary();
 }
diff --git a/backends/prometheus/remote_write/remote_write.h b/backends/prometheus/remote_write/remote_write.h
index edcc477b8d..1307d72810 100644
--- a/backends/prometheus/remote_write/remote_write.h
+++ b/backends/prometheus/remote_write/remote_write.h
@@ -7,21 +7,21 @@
 extern "C" {
 #endif
 
-void init_write_request();
+void backends_init_write_request();
 
-void clear_write_request();
+void backends_clear_write_request();
 
-void add_host_info(const char *name, const char *instance, const char *application, const char *version, const int64_t timestamp);
+void backends_add_host_info(const char *name, const char *instance, const char *application, const char *version, const int64_t timestamp);
 
-void add_tag(char *tag, char *value);
+void backends_add_tag(char *tag, char *value);
 
-void add_metric(const char *name, const char *chart, const char *family, const char *dimension, const char *instance, const double value, const int64_t timestamp);
+void backends_add_metric(const char *name, const char *chart, const char *family, const char *dimension, const char *instance, const double value, const int64_t timestamp);
 
-size_t get_write_request_size();
+size_t backends_get_write_request_size();
 
-int pack_write_request(char *buffer, size_t *size);
+int backends_pack_write_request(char *buffer, size_t *size);
 
-void protocol_buffers_shutdown();
+void backends_protocol_buffers_shutdown();
 
 #ifdef __cplusplus
 }