Apache Web Servers
Reverse Proxy Apache Web Server and Local Apache Web Servers
SFX version 4 runs several Apache HTTP servers, including one for each instance and one that serves as a reverse proxy server, acting as a front end or gateway to the Apache servers of all of the instances. This allows each instance to have its own Apache server and for all instances to be contacted via similar URLs. For example, http://sfx.university.edu:3410/sfxlcl41 and
http://sfx.university.edu:3410/sfxtst41.
http://sfx.university.edu:3410/sfxtst41.
The following diagram illustrates the relationship between the different local Apache servers and the reverse Apache server.
Reverse Proxy Apache
Location of the Apache Configuration Files
The following table lists the location of several important configuration files:
| File | Location |
|---|---|
| Reverse Proxy Apache Configuration | exlibris/sfx_ver/sfx4_1/proxy/conf/httpd.conf |
| Reverse Proxy Apache Configuration (to reference all instances) | /exlibris/sfx_ver/sfx4_1/sfxglb41/config/reverse_proxy_httpd.config__ |
| Instance-specific Local Apache Configuration | /exlibris/sfx_ver/sfx4_1/ <instance_name>/config/ local_httpd.config |
| Instance-specific Apache Configuration | /exlibris/sfx_ver/sfx4_1/ <instance_name>/config/httpd.conf |
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The instance-specific Apache configuration file includes a local file, local_httpd.config, that may contain additions to Apache that are specific to the SFX instance.
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Apache Log Files
All local instance apache log files are stored in the following directory of each instance:
/exlibris/sfx_ver/sfx4_1/<instance>/logs/apache
The reverse proxy apache log files can be found in the following directory:
/exlibris/sfx_ver/sfx4_2/proxy/logs
The apache logs directory contains the following log files
- error_log – This is the place where Apache httpd sends diagnostic information and record any errors that it encounters in processing requests. It is the first place to look when a problem occurs with starting the server or with the operation of the server, since it often contains details of what went wrong and how to fix it.
- access_log – This file contains log records for all requests processed by the server.
Additionally, the sfxglb41 apache logs directory contains the following log file:
- rewrite.log – The purpose of this file is to record all redirections that occur in the apaches httpd. For example, when you change the name of an SFX instance, the log records all of the redirections.
More information about using Apache logs for debugging purposes can be found in Using the Apache Log Files.
For more information on cleaning Apache logs refer to Clean Apache and MySQL Logs and Maintenance Task Checklist.
Apache Error Log Rotation
It is possible to configure Apache to rotate log information based on either a specific time interval (rotation time) or the size of the log file (file size). During log rotation, the old log is kept as is, and a new log file is created, allowing you to save or remove old log information. This option can be used for both error and access logs in both the reverse proxy and local instance apache configuration files.
In the following example, SFX uses Apache's rotatelogs program in conjunction with Apache's piped logfile feature to rotate the reverse proxy Apache error_log file every 24 hours:
- Log on as sfxglb41:
|
vi /exlibris/sfx_ver/sfx4_1/proxy/conf/httpd.conf |
- Change the following line:
|
ErrorLog logs/error_log |
to:
|
ErrorLog "| /exlibris/sfx_ver/sfx4_1/app/apache/bin/rotatelogs /exlibris/sfx_ver/sfx4_1/proxy/logs/error_log.%Y-%m-%d 86400" |
- Save and close the file:
|
:wq |
This rotates the error_log file every 24 hours, creating a log file with the file name: error_log.YYYY-MM-DD.
The rotatelogs tool can be used with the following parameters::
|
rotatelogs [ -l ] [ -f ] logfile rotationtime|filesizeM |
The following are the parameters for this command:
- rotationtime – The time between log file rotations in seconds. The rotation occurs at the beginning of this interval. For example, if the rotation time is 3600, the log file is rotated at the beginning of every hour; if the rotation time is 86400, the log file is rotated every night at midnight. (If no data is logged during an interval, no file is created.)
- filesizeM – The maximum file size in megabytes followed by the letter M to specify size rather than time.