The heartbeat page is a useful page in Sitecore as it shows if Sitecore can connect to it’s databases. If so it will return a 200 status. It can be found at /sitecore/service/heartbeat.aspx and it can be a good practice to point the load balancer’s health check to this page. This will avoid that any traffic is send to a server which cannot connect to its backend database.
Sitecore 9 has introduced a number of new connectionstrings with xConnect and the heartbeat page will fail on these. This can be avoided by adding the new connectionstrings to the excluded connections so the heartbeat page will not return an error while Sitecore’s databases are online. Below is the value which can be used to get the heartbeat page to work in Sitecore 9.
<setting name=”Sitecore.Services.Heartbeat.ExcludeConnection” value=”LocalSqlServer| xconnect.collection| xconnect.collection.certificate| xdb.referencedata.client| xdb.referencedata.client.certificate| xdb.marketingautomation.reporting.client| xdb.marketingautomation.reporting.client.certificate| xdb.marketingautomation.operations.client| xdb.marketingautomation.operations.client.certificate| EXM.CryptographicKey| EXM.AuthenticationKey| Session| sharedSession” />