Hello,
I installed Mailcow on a Testserver at Hetzer which I now wanted to use productive. I found that the certificate has been not renewed and isn’t valid now.
So I wanted to see why and found, that acme could not connect to REDIS. Before the setup ran wihtout problems for a about half a year.
I did a Upate to latest version now, but nothing changed - I don’t see any errors in the redis log.
Below are the logs.

Dovecot

root@Testmailserver:/opt/mailcow-dockerized# docker logs --tail=200 -f mailcowdockerized-dovecot-mailcow-1
Uptime: 0 Threads: 2 Questions: 1 Slow queries: 0 Opens: 17 Open tables: 10 Queries per second avg: 0.000
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- 0:00:04 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 1 seconds. 10 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:06 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 2 seconds. 9 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:05 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 4 seconds. 8 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:05 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 8 seconds. 7 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:05 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 16 seconds. 6 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:06 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 32 seconds. 5 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:06 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 64 seconds. 4 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:05 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 128 seconds. 3 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:05 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 256 seconds. 2 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:06 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Warning: Problem : timeout. Will retry in 512 seconds. 1 retries left.
0 0 0 0 0 0 0 0 --:--:-- 0:00:05 --:--:-- 0curl: (6) Could not resolve host: www.spamassassin.heinlein-support.de
Failed to download SA rules. Exiting.
2024-08-28 20:30:59,763 INFO Set uid to user 0 succeeded
2024-08-28 20:30:59,766 INFO supervisord started with pid 1
2024-08-28 20:31:00,770 INFO spawned: 'processes' with pid 603
2024-08-28 20:31:00,773 INFO spawned: 'dovecot' with pid 604
2024-08-28 20:31:00,775 INFO spawned: 'syslog-ng' with pid 605
Aug 28 20:31:00 6e85f366b77b syslog-ng[605]: syslog-ng starting up; version='4.7.1'
Aug 28 20:31:00 6e85f366b77b dovecot: master: Dovecot v2.3.21.1 (d492236fa0) starting up for imap, sieve, lmtp, pop3
2024-08-28 20:31:01,860 INFO success: processes entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2024-08-28 20:31:01,860 INFO success: dovecot entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2024-08-28 20:31:01,860 INFO success: syslog-ng entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
Aug 28 20:31:10 6e85f366b77b syslog-ng[605]: REDIS server error during connection; driver='d_redis_ui_log#0', error='Operation timed out', time_reopen='60'
Aug 28 20:31:10 6e85f366b77b syslog-ng[605]: REDIS server error during connection; driver='d_redis_f2b_channel#0', error='Operation timed out', time_reopen='60'
Aug 28 20:32:10 6e85f366b77b syslog-ng[605]: REDIS server error during connection; driver='d_redis_f2b_channel#0', error='Operation timed out', time_reopen='60'
Aug 28 20:32:10 6e85f366b77b syslog-ng[605]: REDIS server error during connection; driver='d_redis_ui_log#0', error='Operation timed out', time_reopen='60'
Aug 28 20:33:20 6e85f366b77b syslog-ng[605]: REDIS server error during connection; driver='d_redis_f2b_channel#0', error='Operation timed out', time_reopen='60'
Aug 28 20:33:20 6e85f366b77b syslog-ng[605]: REDIS server error during connection; driver='d_redis_ui_log#0', error='Operation timed out', time_reopen='60'

acme

root@Testmailserver:/opt/mailcow-dockerized# docker logs --tail=200 -f mailcowdockerized-acme-mailcow-1
Could not connect to Redis at redis:6379: Operation timed out
Waiting for Redis...
Could not connect to Redis at redis:6379: Operation timed out
Waiting for Redis...
Could not connect to Redis at redis:6379: Operation timed out
Waiting for Redis...
Waiting for Redis...
Could not connect to Redis at redis:6379: Operation timed out

Redis

root@Testmailserver:/opt/mailcow-dockerized# docker logs --tail=200 -f mailcowdockerized-redis-mailcow-1
1:C 28 Aug 2024 20:12:50.955 # WARNING Memory overcommit must be enabled! Without it, a background save or replication may fail under low memory condition. Being disabled, it can also cause failures without low memory condition, see https://github.com/jemalloc/jemalloc/issues/1328. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
1:C 28 Aug 2024 20:12:50.959 * oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
1:C 28 Aug 2024 20:12:50.959 * Redis version=7.4.0, bits=64, commit=00000000, modified=0, pid=1, just started
1:C 28 Aug 2024 20:12:50.959 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
1:M 28 Aug 2024 20:12:50.960 * monotonic clock: POSIX clock_gettime
1:M 28 Aug 2024 20:12:50.961 * Running mode=standalone, port=6379.
1:M 28 Aug 2024 20:12:50.961 * Server initialized
1:M 28 Aug 2024 20:12:50.961 * Loading RDB produced by version 7.4.0
1:M 28 Aug 2024 20:12:50.961 * RDB age 108 seconds
1:M 28 Aug 2024 20:12:50.961 * RDB memory usage when created 56.32 Mb
1:M 28 Aug 2024 20:12:51.049 * Done loading RDB, keys loaded: 35, keys expired: 0.
1:M 28 Aug 2024 20:12:51.049 * DB loaded from disk: 0.088 seconds
1:M 28 Aug 2024 20:12:51.051 * Ready to accept connections tcp
1:M 28 Aug 2024 20:17:51.101 * 100 changes in 300 seconds. Saving...
1:M 28 Aug 2024 20:17:51.104 * Background saving started by pid 21
21:C 28 Aug 2024 20:17:51.228 * DB saved on disk
21:C 28 Aug 2024 20:17:51.230 * Fork CoW for RDB: current 1 MB, peak 1 MB, average 0 MB
1:M 28 Aug 2024 20:17:51.307 * Background saving terminated with success
1:M 28 Aug 2024 20:29:54.235 * 100 changes in 300 seconds. Saving...
1:M 28 Aug 2024 20:29:54.238 * Background saving started by pid 22
22:C 28 Aug 2024 20:29:54.358 * DB saved on disk
22:C 28 Aug 2024 20:29:54.360 * Fork CoW for RDB: current 1 MB, peak 1 MB, average 0 MB
1:M 28 Aug 2024 20:29:54.441 * Background saving terminated with success

Please help me with this issue

Someone any Idea?
I installed all with the original documentation. Where can I look? Any settings to check?

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Are you sure you have all requirements met (like supported OS, enough memory)? Docker Version >=24, Docker compose >=2.x?
Considered Hetzner specific setup?
UFW and SELinux disabled?

Yes mentioned requirements are met.
As I wrote, it suddenly stopped. But worked before for about half a year withour problems…
I’ve a 4C/8GB RAM Server VPS.

Any more I can check? I’ts just not connecting to Redis…

    ptC7H12 I’ts just not connecting to Redis…

    Maybe some issue with the docker network. Can you open a socket from you host into the IP address 172.x.x.x of Redis container, port 6379?
    If not then something is wrong with your docker network.

        esackbauer Can you help me here? How can I check this? I couldn’t find any realy helpful…

        I found something like this: time docker exec mailcowdockerized-redis-mailcow-1 redis-benchmark -h 127.0.0.1 -p 6379
        This works and gives me results…

          7 days later

          How can I check the Redis connection, please?

          try using telnet, as I have written.

          I don’t see Telnet mentioned above, but thank you.
          I tried following also with localhost, both with same result:
          docker container inspect mailcowdockerized-redis-mailcow-1 | grep -i IPAddress
          this gave me the 172.22.1.249
          Then
          telnet 172.22.1.249 6379
          Result is:
          Trying 172.22.1.249...
          Connected to 172.22.1.249.
          Escape character is '^]'.
          ping
          +PONG

          This look good to me! How should I proceed now?

          I’ve completly reinstalled mailcow and now all works - couldn’t find out, what the problem was…

          No one is typing