Fix: message-id in postprocessor/gelf-chunking

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Fixes
 * gbq connector naming is now `gbq_writer` as it is documented
 * fix gbq connector url missing `/`
+* fix GELF message-id from auto-increment to random-id in postprocessor/gelf_chunking.rs 
 
 ## [0.13.0-rc.29]
 

tremor-interceptor/Cargo.toml

@@ -25,8 +25,7 @@ anyhow = { version = "1.0", default-features = true }
 thiserror = { version = "1.0", default-features = false }
 
 #gelf
-rand = { version = "0.8", optional = true, default-features = false, features = [
-] }
+rand = { version = "0.8", optional = true, default-features = false, features =  ["std_rng"] }
 
 # Compression
 brotli = { version = "6", optional = true, default-features = false, features = [

tremor-interceptor/src/postprocessor/gelf_chunking.rs

@@ -15,6 +15,8 @@
 //! Splits the data using [GELF chunking protocol](https://docs.graylog.org/en/3.0/pages/gelf.html#chunking).
 
 use super::Postprocessor;
+use std::time::{SystemTime, UNIX_EPOCH};
+use rand::{thread_rng,Rng};
 
 #[derive(Clone)]
 pub struct Gelf {
@@ -50,7 +52,46 @@
         if n > 128 {
             return Err(Error::ChunkCount(n));
         };
-        self.id += 1;
+
+
+        /*
+         * REFERENCE(/Explaination) TAKEN FROM: https://github.com/osiegmar/logback-gelf/blob/master/src/main/java/de/siegmar/logbackgelf/MessageIdSupplier.java#L61
+         * 
+         * 
+         * Idea is borrowed from logstash-gelf by <a href="https://github.com/mp911de">Mark Paluch</a>, MIT licensed
+         * <a href="https://github.com/mp911de/logstash-gelf/blob/a938063de1f822c8d26c8d51ed3871db24355017/src/main/java/biz/paluch/logging/gelf/intern/GelfMessage.java">GelfMessage.java</a>
+         *
+         * Considerations about generating the message ID: The GELF documentation suggests to
+         * "Generate from millisecond timestamp + hostname, for example.":
+         * https://go2docs.graylog.org/5-1/getting_in_log_data/gelf.html#GELFviaUDP
+         *
+         * However, relying on current time in milliseconds on the same system will result in a high collision
+         * probability if lots of messages are generated quickly. Things will be even worse if multiple servers send
+         * to the same log server. Adding the hostname is not guaranteed to help, and if the hostname is the FQDN it
+         * is even unlikely to be unique at all.
+         *
+         * The GELF module used by Logstash uses the first eight bytes of an MD5 hash of the current time as floating
+         * point, a hyphen, and an eight byte random number: https://github.com/logstash-plugins/logstash-output-gelf
+         * https://github.com/graylog-labs/gelf-rb/blob/master/lib/gelf/notifier.rb#L239 It probably doesn't have to
+         * be that clever:
+         *
+         * Using the timestamp plus a random number will mean we only have to worry about collision of random numbers
+         * within the same milliseconds. How short can the timestamp be before it will collide with old timestamps?
+         * Every second Graylog will evict expired messaged (5 seconds old) from the pool:
+         * https://github.com/Graylog2/graylog2-server/blob/master/graylog2-server/src/main/java/org/graylog2/inputs/codecs/
+         * GelfChunkAggregator.java Thus, we just need six seconds which will require 13 bits.
+         * Then we can spend the rest on a random number.
+         */
+
+
+        const BITS_13: u64 = 0b1_1111_1111_1111;
+
+        let message_id_current_epoch_time = SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_nanos() as u64;
+
+        let message_id_random_number = thread_rng().gen::<u64>();
+
+        self.id = (message_id_current_epoch_time & BITS_13) | (message_id_random_number & !BITS_13);
+
         Ok(chunks
             .enumerate()
             .map(|(i, chunk)| {