Enable redis backend in 1.20.0

[mzarnowski]

Currently, there is no way to attach the Unbound Container to a Redis Database.
This change compiles the
The resulting image is marginally bigger: < 1%

Verification

Checkout code

cd /tmp
git clone https://github.com/mzarnowski/unbound-docker.git --branch=enable-redis-backend
cd unbound-docker/1.20.0/

Configure unbound

The unbound.conf includes two changes:

Enabled cachedb module:

module-config: "validator cachedb iterator"

Configured Redis connection

cachedb:
    backend: "redis"
    redis-server-host: 10.91.0.20

Start Containers

podman network create foo-net --subnet=10.91.0.0/24

podman run --detach --net=foo-net --name=foo-redis --ip=10.91.0.20 "docker.io/library/redis:7.4.1-alpine3.20" --save 60 1000 --loglevel warning --maxmemory 4mb --maxmemory-policy allkeys-lfu

podman run --detach --net=foo-net --name=foo-unbound -v /tmp/unbound-docker/1.20.0/unbound.conf:/opt/unbound/etc/unbound/unbound.conf:ro,z -p "5353:53/udp" -p "5353:53/tcp" -it localhost/unbound-redis

Observe that Unbound connects to Redis

podman logs foo-unbound

Observe that received DNS request is stored in Redis

dig +short wykop.pl @localhost -p 5353

podman exec -it foo-redis redis-cli keys '*'

Ovserve that after restart, Unbound consults Redis

podman restart foo-unbound
dig +short wykop.pl @localhost -p 5353
podman logs foo-unbound