Apache proxy error states the worker name is too long

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Environment

SUSE Linux Enterprise Server 15 All Service Packs
SUSE Linux Enterprise Server 12 All Service Packs

Situation

An Apache server has the proxy module enabled with a proxy configuration similar to the following:

# cat /etc/apache2/vhosts.d/proxy.conf
<VirtualHost *:80>
    ServerName app.example.com
    ProxyPreserveHost On
    ProxyPass / http://<server>:<port>/<very_long_path>
    ProxyPassReverse / http://<server>:<port>/
</VirtualHost>

In addition to the proxy module, the Apache server could also have the proxy_balancer module enabled with a proxy configuration similar to the following:

# cat /etc/apache2/vhosts.d/proxy.conf
<VirtualHost *:80>
    ServerName app.example.com
    <Proxy "balancer://mycluster">
      BalancerMember "http://<server>:<port>/<very_long_path>"
      BalancerMember "http://<server>:<port>"
    </Proxy>
    ProxyPreserveHost On
    ProxyPass / http://<server>:<port>/<very_long_path>
    ProxyPassReverse / http://<server>:<port>/
</VirtualHost>

Running apachectl -t shows:

apachectl -t
ProxyPass worker name (http://<server>:<port>/<very_long_path>) too long

After starting Apache with systemctl start apache2 following alert is reported in the systemctl status apache2 and the /var/log/apache/error_log:

[<timestamp>] [proxy:error] [pid <number>] AH2808: Alert! worker name
(http://<server>:<port>/<very_long_path>) too long; truncated to: http://<server>:<port>/<shortened_path_to_length_96>

Resolution

Restrict the ProxyPass and/or BalanceMember URL length to 96 characters or less.

PTF can be requested through SUSE Customer Center

Cause

Apache is working as designed. The proxy and proxy_balancer modules have intentionally set PROXY_WORKER_MAX_NAME_SIZE and PROXY_BALANCER_MAX_NAME_SIZE to 96 characters.

Engineering is aware that a limit of 96 characters may be unrealistic and are considering options moving forward.

Status

Reported to Engineering

Disclaimer

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