squid with workers N setting permits http connections

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Environment

SUSE Linux Enterprise Server 12 Service Pack 2 (SLES 12 SP2)
SUSE Linux Enterprise Server 12 Service Pack 3 (SLES 12 SP3)
SUSE Linux Enterprise Server 15

Situation

Squid started with a workers N parameter does not accept connections via http anymore.

N is the number of workers (Squid process daemons) to enable SMP. If it is set to a number >1 (e.g. workers 3), http connections will fail.

After restarting squid, squid doesn't listen on port 3128 (http_port) and "systemctl status squid" and/or the squid/cache.log will show:

commBind: Cannot bind socket FD 20 to [::]: (2) No such file or directory

Resolution

The SLES12 SP3 squid update, squid-3.5.21-26.12.1 and SUSE Linux Enterprise Module for Server Applications 15) squid-4.4-5.3.2, both released November 2018 include the patch to resolve the problem.

Customers using SLES12 SP2 LTSS affected by this issue can alternatively contact SUSE Customer Care to request a PTF (temporary fix).

As a temporary workaround /var/run/squid (with squid:root ownership) can be manually added. However after reboot the directory will be missing again.

Cause

The /var/run/squid directory is missing, so squid can't create the IPC channel sockets (e.g. squid-kid-1.ipc) needed for communication between the processes.

Disclaimer

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