Prometheus File Based Service Discovery

One of the challenges with having a pull model like Prometheus is that it needs to know where the targets are located so it can scrape the metrics. While we can configure static scrape targets in the Prometheus configuration file directly for our local environment I discovered anytime I want to make changes to these setting or add a new target I must restart Prometheus. This can be very annoying, as compared to my Sitecore containers, the Prometheus container takes much longer to stop and restart. So I needed to find a better solution for configuring these targets locally.

Service Discovery

Service Discovery helps solve the problem of identifying scrape targets which is really useful in an orchestrated environment as it will dynamically discover targets. There is support for several common services like:

There are several other methods of Service Discovery supported by Prometheus:

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Sitecore Personalization Rules Vs Caching

I recently ran into an issue with a personalization rule on a rendering that changed the data source for mobile devices, a common scenario if you want to reduce payload and improve mobile experience. However, I discovered if I hit a page with the component on a mobile device I was seeing the desktop version.

Using my SPE script to list component cache settings I discovered the component had “Vary By Data” enabled – could this be the problem? As it turns out it it was. You see Personalization rules enable dynamically changing of components and their data sources. However the “Vary By Data” option causes Sitecore to render cached html markup for the component without performing an actual rendering process. For the majority of scenarios applying personalization rules before retrieving output from cache would make caching almost pointless. But there are certain scenarios, like the one I described above, where this might be beneficial and improve performance. Thankfully, there is a solution using a custom “Vary By Personalized Data” covered here by Ahmed Okour.

It does feel like a gap in Sitecore’s implementation so you either Cache a component or you Personalize it. So this needs to be captured when defining requirements.

Is this component going to be personalized?

  • No – implement caching.
  • Yes – don’t implement caching.
  • Not sure – implement caching and disable it when the component needs to be personalized.
  • Need both – customize with Vary By Personalized Data.

Useful Info

Reset Sitecore Publish Service tables

We ran into an issue with the Sitecore publishing service whereby the following exceptions were being logged:

[Information] Executing Cleanup Task : "PublishOperationCleanupTask-60832bb9509e4a37855285a8346a6a53"

[Error] There was an error adding 1 publisher operations. - Error : "Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding." 

Following some investigation we discovered this was caused by the PublishOperationCleanUpTask running on the PublishService.

The PublishOperationCleanupTask works like the following:

  1. The “Publishing_TargetSyncState” table contains entries containing a publishing target, language, and timestamp
  2. These entries are updated when one of the following publishes is done:
    a. Incremental publish
    b. Publishing the root “sitecore” item with subitems
  3. The PublishOperationCleanupTask checks the entries in the “Publishing_PublisherOperation” table, and removes entries that are older than the timestamp in the “Publishing_TargetSyncState” specific to the language.
  4. This task runs by default once a day but can be configured to run as frequently as required.

So this job is suppose to cleanup Publishing_PublisherOperation table, however on inspection of this table we discovered it contained much older records that had not yet been removed. Indicating the job was having problems completing its task or at least it was not able to cleanout the records.

Part of the solution to resolve the Timeout Expired exception was to increase the <CommandTimeout> setting located in the sc.publishing.sqlazure.xml file. The default value is set to 120.

But what if you wanted to just cleanup the publishing service tables? The following tables are created in the Sitecore master database when you install and setup the publishing service:

  • Publishing_ActivationLock
  • Publishing_Data_Params_FieldIds
  • Publishing_Data_Params_Languages
  • Publishing_JobManifest
  • Publishing_JobMetadata
  • Publishing_JobQueue
  • Publishing_ManifestOperationResult
  • Publishing_ManifestStatus
  • Publishing_PublisherOperation
  • Publishing_TargetSyncState

To reset these tables you can run the following command from the Publish Service webroot: Sitecore.Framework.Publishing.Host schema reset –force

NOTE: The only risk in running this would be if you have any publishing jobs that are in-flight will need to be republished.

Useful Links

Happy Publishing!