Consul 1.2.1 defining health check using pipe in the command argument

Question

I'm using Consul version 1.2.1 and trying to implement health check that runs the command:

# echo ruok | nc localhost 2181
imok

Therefore, I defined the health check in this json file, however, I'm unable to locate any documentation that shows how to handle pipe in the command. Hashi Corp Consul documentation on defining health check is here.

This is what I have tried, but is not correct.

{
  "service": {
    "name": "testapp",
    "port": 2181,
    "check": [
        {
            "args": ["echo ruok | nc localhost 2181"],
            "interval": "15s",
            "timeout": "2s"
        }
    ]
  }
}

Answer 1

You should use script check, and format your json differently in the check section:

{
  "service": {
  "name": "testapp",
  "port": 2181,
  "check": {
             "script": "echo ruok | nc localhost 2181",
             "interval": "15s",
             "timeout": "2s"
           }
    }
}

Answer 2

The script key is deprecated, args is the correct method:

Args (array) - Specifies command arguments to run to update the status of the check. Prior to Consul 1.0, checks used a single Script field to define the command to run, and would always run in a shell. In Consul 1.0, the Args array was added so that checks can be run without a shell. The Script field is deprecated, and you should include the shell in the Args to run under a shell, eg. "args": ["sh", "-c", "..."].

So I have the line:

"args": ["bash", "-c", "/sbin/ss -l | grep vrrp"],

for a check command with a pipe to another command