redis.md in cpl-2.2.0

- old
+ new

@@ -1,17 +1,33 @@
-# Migrating Redis database from Heroku infrastructure
+# Migrating Redis databases
 
-**General considerations:**
+There are two templates examples in this repo:
+- `redis` - basic non-persistent template. It is good for review-apps or staging or where no persistence is required
+- `redis2` - basic persistent template. Good for production where persistence is needed, but cluster is overkill.
 
+## Option 1: use SLAVEOF (easier way)
+
+1. create a redis workload that will accept data
+2. execute `SLAVEOF source_host source_port`, if needed use `masterauth` to provide auth details
+3. wait for replication to pick up all changes (usually quickly), use `INFO` or `DBSIZE` to check progress
+4. stop app completely and ensure nothing is writing to any of redises
+5. execute `SLAVEOF no one` to disconnect replication
+6. switch `REDIS_URL` in the app to point to new server
+7. start the app
+
+## Option 2: use Redis-RIOT (harder way, where option 1 is not possible)
+
+### General considerations:
+
 1. Heroku uses self-signed TLS certificates, which are not verifiable. It needs special handling by setting
-TLS verification to `none`, otherwise most apps are not able to connect.
+The tool that satisfies those criteria is [Redis-RIOT](https://developer.redis.com/riot/riot-redis/index.html)
 
 2. We are moving to private Redis that don't have a public URL, so have to do it from a Control Plane GVC container.
 
 The tool that satisfies those criteria is [Redis-RIOT](https://developer.redis.com/riot/riot-redis/index.html)
 
-**Heroku Redis:**
+### Heroku Redis:
 
 As Redis-RIOT says, master redis should have keyspace-notifications set to `KA` to be able to do live replication.
 To do that:
 
 ```sh
@@ -21,11 +37,11 @@
 Connect to heroku Redis CLI:
 ```sh
 heroku redis:cli -a my-app
 ```
 
-**Control Plane Redis:**
+### Control Plane Redis:
 
 Connect to Control Plane Redis CLI:
 
 ```sh
 # open cpl interactive shell
@@ -34,24 +50,24 @@
 # install redis CLI if you don't have it in Docker
 apt-get update
 apt-get install redis -y
 
 # connect to local cloud Redis
-redis-cli -u MY_CONTROL_PLANE_REDIS_URL
+redis-cli -u MY_CONTROL_PLANE_REDIS_URL -p 6379
 ```
 
-**Useful Redis CLI commands:**
+### Useful Redis CLI commands:
 
 Quick-check keys qty:
 ```
 info keyspace
 
 # Keyspace
 db0:keys=9496,expires=2941,avg_ttl=77670114535
 ```
 
-**Create a Control Plane sync workload**
+### Create a Control Plane sync workload
 
 ```
 name: riot-redis
 
 suspend: true
@@ -74,10 +90,10 @@
   ...your_control_plane_redis_host...
   --mode
   live
 ```
 
-**Sync process**
+### Sync process
 
 1. open 1st terminal window with heroku redis CLI, check keys qty
 2. open 2nd terminal window with controlplane redis CLI, check keys qty
 3. start sync container
 4. open logs with `cpl logs -a my-app -w riot-redis`