How to configure multiple ports with App Health Checks
Article ID: 298381
Updated On:
Products
Issue/Introduction
According to the docs for "Using App Health Checks " , it states that if setting Health Check Type with port. See example below:
A health check makes a TCP connection to the port or ports configured for the app. For apps with multiple ports, a health check monitors each port.
You may question how to configure multiple ports to monitor them with App Health Checks. This article introduces how to configure multiple ports with App Health Checks.
Environment
Resolution
First, you will need to develop your target application to listen with multiple ports to be monitored on Tanzu Application Service. For examples, please suppose that your particular application listens with port 7777 and port 8888.
By default, App Health Checks are performed for port 8080 only. You must set the ports manually to monitor with App Health Checks feature as the cf command shows below:
cf curl /v2/apps/<TARGET_APP_GUID> -X PUT -d '{"ports": [7777,8888]}'
This modification is immediately applied. Now, you will see multiple heathcheck processes in Diego Cell VMs hosting the target application instances as shown below and you will see a health check monitors each port:
diego_cell/****97c3-**c0-**5f-**d3-**ec95a4411d:~# ps auxwww | grep healthcheck : 4294967+ 2735806 0.0 0.0 706260 4040 ? Ssl 07:26 0:00 /etc/cf-assets/healthcheck/healthcheck -port=8888 -timeout=1000ms -liveness-interval=30s 4294967+ 2735818 0.0 0.0 706260 4208 ? Ssl 07:26 0:00 /etc/cf-assets/healthcheck/healthcheck -port=7777 -timeout=1000ms -liveness-interval=30s
Once one of healthcheck processes fails to monitor the target port, the target application is considered as crashed.
If you want to check the actual monitoring behavior with multiple ports quickly, you can use the following sample go application which can listen with multiple ports.
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