Define ScyllaDB as drop-in replacement for Cassandra (jaegertracing#4353

)

## Which problem is this PR solving?

Defines that Jaeger server supports ScyllaDB as a storage backend as a
drop-in replacement for Cassandra

## Short description of the changes
Updated README.md

---------

Signed-off-by: Maxim Korolyov <[email protected]>
Signed-off-by: Maxim Korolyov <[email protected]>
Co-authored-by: Yuri Shkuro <[email protected]>

README.md

@@ -85,7 +85,8 @@ Jaeger can be used with a growing a number of storage backends:
 * It natively supports two popular open source NoSQL databases as trace storage backends: Cassandra and Elasticsearch.
 * It integrates via a gRPC API with other well known databases that have been certified to be Jaeger compliant: [TimescaleDB via Promscale](https://github.com/timescale/promscale), [ClickHouse](https://github.com/jaegertracing/jaeger-clickhouse).
 * There is embedded database support using [Badger](https://github.com/dgraph-io/badger) and simple in-memory storage for testing setups.
-* There are ongoing community experiments using other databases, such as ScyllaDB, InfluxDB, Amazon DynamoDB, YugabyteDB(YCQL).
+* ScyllaDB [can be used](https://github.com/jaegertracing/jaeger/blob/main/plugin/storage/scylladb/README.md) as a drop-in replacement for Cassandra since it uses the same data model and query language.
+* There are ongoing community experiments using other databases, such as InfluxDB, Amazon DynamoDB, YugabyteDB(YCQL).
 
 ### Modern Web UI
 

plugin/storage/scylladb/README.md

@@ -0,0 +1,43 @@
+## ScyllaDB as a storage backend
+Jaeger could be configured to use ScyllaDB as a storage backend. This is an experimental feature and this is not an officially supported backend, meaning that Jaeger team will not proactively address any issues that may arise from incompatibilities between the ScyllaDB and Cassandra databases (the team may still accept PRs).
+
+### Configuration
+
+Setup Jaeger server to use Cassandra database and just replace conn string to ScyllaDB cluster. No additional configuration is required.
+
+### Known issues
+
+#### Protocol version
+
+Jaeger server detects Cassandra protocol version automatically. At the date of the demo with specified versions server detects that it connected via protocol version 3 while it is actually 4. This leads to warn log in cassandra-schema container:
+```
+WARN: DESCRIBE|DESC was moved to server side in Cassandra 4.0. As a consequence DESRIBE|DESC will not work in cqlsh '6.0.0' connected to Cassandra '3.0.8', the version that you are connected to. DESCRIBE does not exist server side prior Cassandra 4.0.
+Cassandra version detected: 3
+```
+
+Otherwise, it should be fully compatible.
+
+### Demo
+
+Docker compose file consists of Jaeger server, Jaeger Cassandra schema writer, Jaeger UI, Jaeger Demo App `HotRod` and a ScyllaDB cluster.
+
+There is a known issue with docker compose network configuration and containers connectivity on Apple silicone. Sometimes it's helpful to manually create the docker network before running `docker compose up`:
+```shell
+docker network create --driver bridge jaeger-scylladb
+```
+
+#### Spin up all infrastructure:
+
+```shell
+docker compose up -d
+```
+Will:
+1. Create ScyllaDB cluster with 3 nodes(about 1 min to initialize)
+2. Generate the schema for jaeger key space
+3. Start Jaeger server, Jaeger UI and Jaeger Demo App `HotRod`
+
+#### Run demo app
+
+1. Wait till all containers are up and running
+2. Open Demo app in your browser: http://localhost:8080 and click some buttons.
+3. Open Jaeger UI in your browser: http://localhost:16686 and check traces

plugin/storage/scylladb/docker-compose.yml

@@ -0,0 +1,91 @@
+networks:
+  jaeger-scylladb:
+    external: true
+    driver: bridge
+
+services:
+  collector:
+    restart: unless-stopped
+    image: jaegertracing/jaeger-collector:1.43
+    environment:
+      SPAN_STORAGE_TYPE: cassandra
+      CASSANDRA_SERVERS: scylladb
+      CASSANDRA_KEYSPACE: jaeger_v1_test
+    networks:
+      - jaeger-scylladb
+    depends_on:
+      - cassandra-schema
+
+  web:
+    image: jaegertracing/jaeger-query:1.43
+    restart: unless-stopped
+    ports:
+      - 16686:16686
+      - 16687:16687
+    environment:
+      SPAN_STORAGE_TYPE: cassandra
+      CASSANDRA_SERVERS: scylladb
+      CASSANDRA_KEYSPACE: jaeger_v1_test
+    networks:
+      - jaeger-scylladb
+    depends_on:
+      - cassandra-schema
+
+  cassandra-schema:
+    image: jaegertracing/jaeger-cassandra-schema:1.43
+    environment:
+      CASSANDRA_PROTOCOL_VERSION: 4
+      CASSANDRA_VERSION: 4
+      CQLSH_HOST: scylladb
+      DATACENTER: test
+      MODE: test
+    networks:
+      - jaeger-scylladb
+    depends_on:
+      scylladb:
+        condition: service_healthy
+
+  scylladb:
+    restart: always
+    image: scylladb/scylla:5.1.7
+    ports:
+      - 9042:9042
+    volumes:
+      - .docker/scylladb/1:/var/lib/scylla
+    networks:
+      - jaeger-scylladb
+    healthcheck:
+      test: ["CMD", "cqlsh", "-e", "describe keyspaces"]
+      interval: 1s
+      retries: 120
+      timeout: 1s
+
+  scylladb2:
+    restart: always
+    image: scylladb/scylla:5.1.7
+    command: --seeds=scylladb
+    volumes:
+      - .docker/scylladb/2:/var/lib/scylla
+    networks:
+      - jaeger-scylladb
+
+  scylladb3:
+    restart: always
+    image: scylladb/scylla:5.1.7
+    command: --seeds=scylladb
+    volumes:
+      - .docker/scylladb/3:/var/lib/scylla
+    networks:
+      - jaeger-scylladb
+
+  hotrod:
+    image: jaegertracing/example-hotrod:latest
+    ports:
+      - 8080:8080
+    command: [ "all" ]
+    environment:
+      - OTEL_EXPORTER_JAEGER_ENDPOINT=http://collector:14268/api/traces
+    networks:
+      - jaeger-scylladb
+    depends_on:
+      - collector