Redict

Seamless migration between providers

We have tested a seamless migration from Redis to Redict on our production deployment. To reproduce:

We have deployed Redict to our production cluster.
- Defaults have been changed to:
```
with_redis: false
with_redict: true
```
  These can be changed in their respective vars/ files.
- Run
```
DEPLOYMENT=prod TAGS=redict make deploy
```
Using remote shell and redict-cli run:
```
replicaof redis 6379
```
This converts the Redict instance into a read-only replica of the Redis.
After the data exchange is done, change all references in variables to redis to point to the new hostname, in this case redis → redict.
- Run
```
DEPLOYMENT=prod TAGS=packit-service-beat,fedmsg,packit-worker,packit-service make deploy
```
Simultaneously run the deployment with the changed hostnames and via redict-cli run:
```
replicaof no one
```
to make the redict deployment the primary one.
(optional) For safety reasons and easier rollback, it's possible to convert the former Redis deployment into a replica of Redict, just in case it needs to be reverted without loss of data. For this you can run in redis-cli:
```
replicaof redict 6379
```

References to Redis

Redis is being referenced from: