Rules of AEM

Crypto Support in AEM (Syncing HMAC among AEM instances) AEM OOTB provides a feature where we can encrypt the secured and confidential data through OOTB AEM Crypto Support and store it in a code repository in the form of OSGi configuration. Crypto Support is based on keys (hmac and master files) which are unique for each AEM instance. Encrypted text generated for the same plain-text string on one AEM instance will be different from another instance. This can raise alarms in cases where we have the same OSGi configuration values shared among Author and Publish instances under the same topology. For e.g. /apps/project/config.prod/com.day.cq.db.dbservice.xml Here DB password for Default DB Service will be same across all Prod AEM instances. So, in order to make sure that the same encrypted value works on all Prod instances, we will have to sync hmac and master files among Prod Author and Publish instances. Vital Points to know before HMAC SYNC  Sync of HMAC/keys will break the AEM SSL and

LOGGING OF THE X-FORWARDED-FOR HEADER The dev-opes team , struggles to find the end user IP while working / troubleshooting the DOS, D-DOS attacks/issue.  To troubleshoot such issue first thing you need to do is , log the end user IP.  Please follow the steps to do the same.  In the Apache HTTP Server's access_log, add this to the httpd.conf file in the dispatcher servers: LogFormat "%{X-Forwarded-For}i %h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent In Microsoft IIS add X-Forwarded-For in the  "Advanced Logging"  configuration. That would log the correct end-user IP. Use the output showing the IP and User-Agent to analyse whether it is a malicious attack and block the offending IPs if it makes sense. 2. SET DISPATCHER.LOG'S LOG LEVEL TO DEBUG:

Prevent Denial of Service (DoS) Attacks : AEM  A denial of service (DoS) attack is an attempt to make a computer resource unavailable to its intended users. At the dispatcher level, there are two methods of configuring to prevent DoS attacks: Use the mod_rewrite module (for example,  Apache 2.4 ) to perform URL validations (if the URL pattern rules are not too complex). Prevent the dispatcher from caching URLs with spurious extensions by using  filters .  For example, change the caching rules to limit caching to the expected mime types, such as .html .jpeg .gif .swf .js .doc .pdf .ppt .... as per your project requirement. An example configuration file is given below,  for  this includes restrictions for mime types.      When configuring Dispatcher you should restrict external access as much as possible. The      following example provides example for the minimal access for external visitors, you can refer the default file.  /filter { # Deny everything first and then allow s

Upgrading the dispatcher module in AEM Often the AEM dev-ops team faces the challenge on Dispatcher upgradation. It is not clear anywhere how to do it and what precautions one should take while doing the same.  In this article we will cover these steps,  Upgrading the Dispatcher Module : Step 1 -  Download the required dispatcher module version from the  Adobe dispatcher download page  ,  Make sure you download the dispatcher version module as per the OS. https://experienceleague.adobe.com/docs/experience-manager-dispatcher/using/getting-started/release-notes.html?lang=en Step 2 -  Extract the dispatcher module at some location on server or local machine.                      tar -xvzf <dispatcher-xxxxxxxx.tar.gz> (linux)  Step 3 -  Copy the extracted dispatcher-xxxxxxxxxx.so file to the module folder of the server.                          Module folder location can vary based on OS, Installation Type. hence please make sure you find the correct module folder.  Step 4 - Set the

AWS: Pre-Warming the Load Balancer How to Resolve Load balancer request over flow for a sudden traffic spike ?  Load balancer is giving 504 error ? Load balancer is giving target connection  error ? If you are facing such issues ,  please read this article to get the solution.  Do you expect a spike in traffic? Let’s say your stakeholders expect a ramp of 20000 users in the first minutes of your website. How do you handle a scenario where you expect tens of thousands of users in the first minutes since the launch of your website? This is a great example of handling fault tolerance in AWS. If one wants to achieve fault tolerance in AWS, there a few options to do that: Use a Load Balancer – no matter how much the traffic increases, if you place your instances behind a Load Balancer it is always a great idea because the traffic is balanced across all the healthy instances. Use an Auto Scaling Group – Load balancer can scale up/down with as many instances as you want, this is a really po

How to Delete Dispatcher cache without logging into the Dispatcher servers? Our Authoring team faces day to day challenges while deleting/flush the dispatcher cache. when the changes are not visible on server. They have to be depended on the IT operations/Dev ops teams to do the same. Which some time get very much time consuming for a small work.  In this article we will see it can be configure and used by Author UI itself.  This will allow  AEM authors (or “super authors”) to flush parts of the dispatcher cache manually without the involvement of IT Operations. How to Use 1. Log in to AEM Author 2. Download the ACS commons tool from  ACS Commons Official page 3. Install the downloaded package via aem package manager.   4. Make sure you create the dispatcher flush agents on Author for all Dispatchers. from http://<<host:port>>/miscadmin#/etc/replication/agents.author, check the NOTE's part at the end of page. 5. Navigate to Tools 6. Under the acs-commmons/dispatcher-flu

 Managing AEM Repository Size Growth Managing your AEM repository size growth can be challenging for numerous reasons. What’s more, it may suddenly start to grow unexpectedly and fill up space in the assigned drive of your AEM application. In this post, I want to share a few AEM utilities & methods which can help you to not only manage the AEM repository size but also help to improve the AEM application performance. 1: Tar Compaction (also known as Revision Cleanup) By running the regular tar compaction, you can not only control the AEM repository size growth, but it will also help improve the AEM application performance. Tar compaction reclaims the disk space by removing the obsolete/redundant data from your AEM application. You can use both online and offline compaction. You can schedule online Tar compaction during weekdays after business hours & offline compaction on weekends (Non-business hours or during your designated Maintenance Window). 2: Garbage Collection By running

The dispatcher is used as a load balancing/caching tool by AEM. It can also be used to block anyone from accessing your AEM author instance. This is to ensure that no one outside the client’s network can access it. AEM Author and publisher should never be exposed directly. In most cases, clients may also require a block to be put on AEM pub dispatchers before going live. This is to ensure that no one can see the site except for the client so performance, penetration, and UAT testing can be performed before going live. In this article, we will see, 5 easy steps to enable IP whitelisting in Apache so only the allowed list of IPs have access to AEM through the dispatcher. 1) In Apache to enable whitelisting, the Require directive is used which is provided by the mod_authz_host module. Make sure that you have the module enabled first in  /dispatcher/src/conf.modules.do/00-base.conf LoadModule authz_host_module modules/mod_authz_host.so 2) In the ams default variable file /dispatcher/src/c

How to create AEM package via CURL  Most of our dev ops and AEM developers face issue while automating the AEM package creation via Curl.  I will explain the command and process for it.  in AEM package creation is a 3 steps process.  1- AEM package creation  2 - Filter addition  3- Package build Let's see all these 3 steps in detail -  AEM package creation  it is simple step -  curl -u admin:admin -X POST http://localhost:4502/crx/packmgr/service/.json/etc/packages/my_packages/testpackage?cmd=create \ -d packageName=testpackage \ -d groupName=my_packages Filter Addition  This is a complex step where you need to be careful while adding the parameters.  General command , in this " /content/my-site" is my package filter. You can also define the rule like exclude in exclude section.  curl -u admin:admin -X POST http://localhost:4502/crx/packmgr/update.jsp \ -F path=/etc/packages/my_packages/testpackage.zip -F packageName=testpackage \ -F groupName=my_packages \ -F filter=&q

How to Increase Apache Request Per Second ? By default, Apache web server is configured to support 160 requests per second. As your website traffic increases, Apache will start dropping additional requests and this will spoil customer experience.  Here’s how to increase Apache requests per second. 1. Install MPM module We need to install MPM Apache module to be able to increase Apache requests per second. You can use mpm_worker or mpm_event module for this, instead of mpm_prefork module which consumes a lot of memory. You can easily install MPM module in Apache with following command For CentOS7/RHEL7 : Adjust /etc/httpd/conf.modules.d/00-mpm.conf Comment the line LoadModule mpm_prefork_module modules/mod_mpm_prefork.so by adding # in front of it. Uncomment the line LoadModule mpm_worker_module modules/mod_mpm_worker.so by removing # in front of it. For Ubuntu/Debian :  Use a2dismod / a2enmod to disable mpm_prefork and enable mpm_worker 2. Increase Max Connections in Apache Open MP

ACL's and how they are evaluated ? AEM Developers, Infrastructure Engineers / Dev-ops teams working in any domain regularly come across a challenge for understanding the ACL & its evaluation mechanism.  Adobe Experience Manager is designed to cater for content authoring of multiple sites by multiple content authors. Naturally, this process needs to be controlled by strict Access Control Lists (ACLs) to manage. AEM WCM uses Access Control Lists (ACLs) to organise the permissions being applied to the various pages. This article addresses in a simple way on how to understand the ACL's , its different ways,  This article covers the following - How can we read and understand the ACL.  Evaluation of user permissions.  Concurrent Permission on ACL Access Control Lists are made up of the individual permissions and are used to determine the order in which these permissions are actually applied. The list is formed according to the hierarchy of the pages under consideration. How can w