Enable TLS support for Redis

Cargo.toml

@@ -63,7 +63,7 @@ num_cpus = "1.0"
 number_prefix = "0.4"
 percent-encoding = { version = "2", optional = true }
 rand = "0.8"
-redis = { version = "0.17", optional = true }
+redis = { version = "0.17", optional = true, default-features = false, features = ["aio", "tls", "tokio-comp", "tokio-tls-comp"] }
 regex = "1"
 reqwest = { version = "0.10", features = ["json", "blocking"], optional = true }
 retry = "1"

README.md

@@ -163,6 +163,8 @@ You can also define a prefix that will be prepended to the keys of all cache obj
 ### Redis
 Set `CACHEPOT_REDIS` to a [Redis](https://redis.io/) url in format `redis://[:<passwd>@]<hostname>[:port][/<db>]` to store the cache in a Redis instance. Redis can be configured as a LRU (least recently used) cache with a fixed maximum cache size. Set `maxmemory` and `maxmemory-policy` according to the [Redis documentation](https://redis.io/topics/lru-cache). The `allkeys-lru` policy which discards the *least recently accessed or modified* key fits well for the cachepot use case.
 
+Redis over TLS is supported. Use the [`rediss://`](https://www.iana.org/assignments/uri-schemes/prov/rediss) url scheme (note `rediss` vs `redis`). Append `#insecure` the the url to disable hostname verification and accept self-signed certificates (dangerous!). Note that this also disables [SNI](https://en.wikipedia.org/wiki/Server_Name_Indication).
+
 ### Memcached
 Set `CACHEPOT_MEMCACHED` to a [Memcached](https://memcached.org/) url in format `tcp://<hostname>:<port> ...` to store the cache in a Memcached instance.