Add metadata ADR

README.md

@@ -30,6 +30,7 @@ This repo is used to capture architectural and design decisions as a reference o
 |[ADR-22](adr/ADR-22.md)|jetstream, client|JetStream Publish Retries on No Responders|
 |[ADR-31](adr/ADR-31.md)|jetstream, client, server|JetStream Direct Get|
 |[ADR-32](adr/ADR-32.md)|client|Service API|
+|[ADR-33](adr/ADR-33.md)|jetstream, client, server|Metadata for Stream and Consumer|
 
 ## Jetstream
 
@@ -50,6 +51,7 @@ This repo is used to capture architectural and design decisions as a reference o
 |[ADR-22](adr/ADR-22.md)|jetstream, client|JetStream Publish Retries on No Responders|
 |[ADR-28](adr/ADR-28.md)|jetstream, server|JetStream RePublish|
 |[ADR-31](adr/ADR-31.md)|jetstream, client, server|JetStream Direct Get|
+|[ADR-33](adr/ADR-33.md)|jetstream, client, server|Metadata for Stream and Consumer|
 
 ## Kv
 
@@ -79,21 +81,22 @@ This repo is used to capture architectural and design decisions as a reference o
 
 ## Server
 
-| Index                   |Tags|Description|
-|-------------------------|----|-----------|
-| [ADR-1](adr/ADR-1.md)   |jetstream, client, server|JetStream JSON API Design|
-| [ADR-2](adr/ADR-2.md)   |jetstream, server, client|NATS Typed Messages|
-| [ADR-3](adr/ADR-3.md)   |observability, server|NATS Service Latency Distributed Tracing Interoperability|
-| [ADR-4](adr/ADR-4.md)   |server, client|NATS Message Headers|
-| [ADR-5](adr/ADR-5.md)   |server, client|Lame Duck Notification|
-| [ADR-6](adr/ADR-6.md)   |server, client|Naming Rules|
-| [ADR-7](adr/ADR-7.md)   |server, client, jetstream|NATS Server Error Codes|
-| [ADR-9](adr/ADR-9.md)   |server, client, jetstream|JetStream Consumer Idle Heartbeats|
-| [ADR-10](adr/ADR-10.md) |server, client, jetstream|JetStream Extended Purge|
-| [ADR-28](adr/ADR-28.md) |jetstream, server|JetStream RePublish|
-| [ADR-30](adr/ADR-30.md) |server|Subject Transform|
-| [ADR-31](adr/ADR-31.md) |jetstream, client, server|JetStream Direct Get|
-| [ADR-26](adr/ADR-26.md) |server|NATS Authorization Callouts|
+|Index|Tags|Description|
+|-----|----|-----------|
+|[ADR-1](adr/ADR-1.md)|jetstream, client, server|JetStream JSON API Design|
+|[ADR-2](adr/ADR-2.md)|jetstream, server, client|NATS Typed Messages|
+|[ADR-3](adr/ADR-3.md)|observability, server|NATS Service Latency Distributed Tracing Interoperability|
+|[ADR-4](adr/ADR-4.md)|server, client|NATS Message Headers|
+|[ADR-5](adr/ADR-5.md)|server, client|Lame Duck Notification|
+|[ADR-6](adr/ADR-6.md)|server, client|Naming Rules|
+|[ADR-7](adr/ADR-7.md)|server, client, jetstream|NATS Server Error Codes|
+|[ADR-9](adr/ADR-9.md)|server, client, jetstream|JetStream Consumer Idle Heartbeats|
+|[ADR-10](adr/ADR-10.md)|server, client, jetstream|JetStream Extended Purge|
+|[ADR-26](adr/ADR-26.md)|server|NATS Authorization Callouts|
+|[ADR-28](adr/ADR-28.md)|jetstream, server|JetStream RePublish|
+|[ADR-30](adr/ADR-30.md)|server|Subject Transform|
+|[ADR-31](adr/ADR-31.md)|jetstream, client, server|JetStream Direct Get|
+|[ADR-33](adr/ADR-33.md)|jetstream, client, server|Metadata for Stream and Consumer|
 
 ## When to write an ADR
 

adr/ADR-33.md

@@ -0,0 +1,51 @@
+# Metadata for Stream and Consumer
+
+|Metadata|Value|
+|--------|-----|
+|Date    |2023-01-23|
+|Author  |@Jarema|
+|Status  |Approved|
+|Tags    |jetstream, client, server|
+
+## Context and Problem Statement
+
+Until now, there was no way to easily add additional information about Stream or Consumer.
+The only solution was using `Description` field, which is a not ergonomic workaround.
+
+## Server PR
+https://github.com/nats-io/nats-server/pull/3797
+
+## Design
+
+The solution is to add new `metadata` field to both `Consumer` and `Stream` config.
+The `metadata` field would by a map of `string` keys and `string` values.
+
+### JSON representation
+The map would be represented in json as object with nested key/value pairs, which is a default
+way to marshal maps/hashmaps in most languages.
+
+### Size limit
+To avoid abuse of the metadata, the size of it is limited to 128KB.
+Size is equal to len of all keys and values summed.
+
+### Reserved prefix
+`_nats` is a reserved prefix.
+Will be used for any potential internals of server or clients.
+Server can lock its metadata to be immutable and deny any changes.
+
+
+### Example
+```json
+{
+  "durable_name": "consumer",
+  ... // other consumer/stream fields
+  "metadata": {
+    "owner": "nack",
+    "domain": "product",
+    "_nats_created_version": "1.10.0"
+  }
+}
+
+```
+
+