Celery can't find Redis in Kubernetes

Question

I am running Celery in Kubernetes pod. It can't find the server:

ERROR/MainProcess] consumer: Cannot connect to redis://:**@redis-master:6379/1: Error -3 connecting to redis-master:6379. Lookup timed out.. Trying again in 4.00 seconds... (1/100)

If I connect to the very same pod via "kubectl exec -it" and run the command, I succeed:

redis-cli -u redis://:@redis-master:6379/1 keys '*'

(empty list or set)

How can I troubleshoot this problem?

---

UPDATE 1: Problem obviously in DNS:

If I set host to domain name:

export REDIS_HOST=redis-master.dev.svc.cluster.local
celery worker --app src
TIMEOUT

If I set host to domain name:

export REDIS_HOST=10.0.13.13
celery worker --app src
OK

Meanwhile:

# dig redis-master.dev.svc.cluster.local
; <<>> DiG 9.11.5-P4-5.1+deb10u1-Debian <<>> redis-master.dev.svc.cluster.local
;; global options: +cmd
;; Got answer:
;; WARNING: .local is reserved for Multicast DNS

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49071
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;redis-master.dev.svc.cluster.local. IN A

;; ANSWER SECTION:
redis-master.dev.svc.cluster.local. 30 IN A 10.0.13.13

;; SERVER: 10.0.0.10#53(10.0.0.10)

Thus, the problem is narrowed down to: Why Celery doesn't use DNS?

---

UPDATE 2: Problem in Python library dnspython. Version 2.0.0 - bug in resolving Version 1.16.0 - works like a charm

---

SOLUTION

pip install dnspython==1.16.0

Answer 1

Answering myself:

This is a dnspython bug. Solution:

pip install dnspython==1.16.0