Migrating IBM HTTP Server 8.5 configurations to 9.0 in place

Steps

1. Stop IHS
2. Backup your IHS installation directory
3. Use IBM Installation Manager to uninstall IHS 8.5

   /opt/IBM/InstallationManager/eclipse/tools/imcl uninstall com.ibm.websphere.IHS.v85 -id /opt/IHS
4. Create an archive of the added and customized files left after uninstallation: 
    

   tar -C /opt  --exclude java --exclude logs \
      --exclude conf/postinst.properties  --exclude properties \
      -cvf /opt/IHSmigrate.tar IHS

   Windows: Windows 2019 and later includes tar. For earlier Windows releases, zip the installation root but omit the paths listed with --exclude in the example.
5. Remove the original IHS installation directory: 

   rm -rf /opt/IHS

   Windows: RD /S "\Program Files\IBM\IHS"
6. Install IHS 9.0 to the same directory:
    

   /opt/IBM/InstallationManager/eclipse/tools/imcl \
       install com.ibm.websphere.IHS.v90 com.ibm.java.jdk.v8 \
       -repositories https://www.ibm.com/software/repositorymanager/V9WASSupplements   \
       -id /opt/IHS -showProgress -prompt -acceptLicense

   In place of the URL argument to the -repositories flag (https://www.ibm.com/software/repositorymanager/V9WASSupplements), two local paths can be provided with a comma separator:

   1. A downloadable fix pack for the WebSphere supplements, such as 9.0.5-WS-IHSPLG-FP011.zip
   2. A downloadable fix pack for "IBM SDK Java Technology Edition Version 8.0 for WebSphere Application Server V9 and WebSphere Liberty using Installation Manager" from such as 8.0.7.6-JavaSE-SDK-linux-x64-repo.zip   
7. Unpack the archive created in step 4 to restore added and changed configuration files:

   tar -C /opt/ -xvf /opt/IHSmigrate.tar

8. At this stage, the overlayed config is not yet expected to work with IHS 9.0.  Append the following snippet to the bottom of conf/httpd.conf and conf/admin.conf (if used)
    

   # Snippet to aid in migration from an IHS 8.5.5 configuration to IHS 9.0 
   # The goal is to minimize the number of small in-line changes needed to update an 855 config.
   # Version 1.0.1
   
   <IfFile modules/mod_unixd.so>
     LoadModule unixd_module modules/mod_unixd.so
   </IfFile>
   
   <IfFile modules/mod_mpm_event.so>
     LoadModule mpm_event_module modules/mod_mpm_event.so
   </IfFile>
   
   # Delete this after purging Order, Deny, and Allow from the configuration
   LoadModule access_compat_module modules/mod_access_compat.so
   
   <IfModule !authn_core_module>
     LoadModule authn_core_module modules/mod_authn_core.so
   </IfModule>
   
   <IfModule !authnz_core_module>
     LoadModule authz_core_module modules/mod_authz_core.so
   </IfModule>
   
   <Files ~ "^\.ht">
      Require all denied
      Forbid
   </Files>
   
   <IfModule mod_access_compat.c>
     <Directory />
        Order allow,deny 
        deny from all
     </Directory>
    </IfModule>
   
   <IfModule !mod_access_compat.c>
     <Directory />
        require all denied
     </Directory>
   </IfModule>
   
   # Update some older defaults
   ServerSignature OFF
   LogFormat "%h %l %u %t \"%r\" %>s %b %D \"%{WAS}e\" %X" common
   <IfModule mod_mpmstat.c>
     TrackHooksOptions notice
   </IfModule>
9. Linux only:
   
   Remove the <IfModule worker.c> and the </IfModule> that follows it, leaving the contained directives. On Linux, IHS uses the "event" MPM and this stanza hides the MPM configuration and triggers a warning.
   
   Locate the existing  ServerLimit directive and double the value.  Nearby values  do not have to be adjusted and doubling the value should have no negative effects.  In 9.0, IHS uses the additional space above what would be needed (ThreadsPerChild  / MaxClients) to hold information about processes that are exiting.  
10. IHS 9.0.5.12 and earlier only:   
    
    Remove the line 'LoadModule authz_default_module modules/mod_authz_default.so' from conf/httpd.conf and conf/admin.conf.  9.0.5.13 and later silently handles this IHS 8.5.5 specific entry.
11. If the configuration contains "htpasswd" based authentication, add "AuthBasicProvider file" to each configuration stanza with "AuthUserFile"
12. Run a configuration test:

    /opt/IHS/bin/apachectl -t 

    
    If an error is reported, review the directive name in the list here and load the missing module: https://publib.boulder.ibm.com/httpserv/manual24/mod/directives.html
    If the error refers to missing symbols such as "ap_my_generation" or "ap_log_error" or referring to "expected signature 41503234 but saw 41503232 ", it is likely a path to a third-party module needs to be updated to compile against Apache 2.4.
    
    Windows: Use bin\httpd.exe -t
     
13. If the IHS admin server is used, repeat the preceding step with an additional argument of:  "-f conf/admin.conf"

    /opt/IHS/bin/apachectl -t -f conf/admin.conf

    Windows: Use bin\httpd.exe -t -f conf\admin.conf
     
14.  Replace deprecated access control (optional but recommended)
    
    Using a mix of `Require` and the deprecated "Order", "Allow", and "Deny" can have unexpected effects.  It is recommended to purge the configuration of the latter directives and comment out the LoadModule for mod_access_compat.  For more information, refer to https://publib.boulder.ibm.com/httpserv/manual24/upgrading.html#access
15. After the deprecated directives have been removed, add a "#" character to comment out "LoadModule access_compat_module modules/mod_access_compat.so" and re-test the configuration (apachectl -t) to catch any missed directives or typographical errors.
16. Once the config test runs successfully, start the server and test any paths that were updated
17. Migrate the WebSphere WebServer plug-in installation from 8.5 to 9.0
    1. Backup the contents of the WebSphere WebServer plug-in installation root
    2. Create an archive of the config directory:

       tar -C  /opt --exclude actionRegistry -cvf /opt/PLGmigrate.tar Plugins/config

    3. Uninstall the 8.5 WebSphere WebServer plug-in

       /opt/IBM/InstallationManager/eclipse/tools/imcl uninstall com.ibm.websphere.PLG.v85 -id /opt/Plugins

    4. Remove the 8.5 WebSphere WebServer plug-in installation directory

       rm -rf /opt/Plugins

    5. Install the 9.0 WebSphere WebServer Plugin to the same installation directory

       /opt/IBM/InstallationManager/eclipse/tools/imcl \
           install com.ibm.websphere.PLG.v90 com.ibm.java.jdk.v8 \
           -repositories https://www.ibm.com/software/repositorymanager/V9WASSupplements   \
           -id /opt/Plugins -showProgress -prompt -acceptLicense

    6. Restore the config directory from the archive

       tar -C /opt/ -xvf /opt/PLGmigrate.tar