无限循环等待变量值改变，每30秒检查一次mongo shell

Question

Writing a bash script where I connect to mongo-shell. I have the following output for rs.status() . I have to wait for one of the members to change the value of stateStr to Secondary . In the output below, you can see, right now it says Not active . I want to write an infinite loop which will iterate through the all the members, and check the stateStr every 30 seconds until the there is a Secondary .

"members" : [
  { "stateStr" : "Not active" },
  { "stateStr" : "PRIMARY" },
  { "stateStr" : "ARBITER" }
],

Here's what I have so far:

mongo --host ${other_host} ${ssl_mode} <<EOF
    while (true){
            for (i = 0; i <= 2; i++){
                    if (rs.status().members[i].stateStr == "SECONDARY") {
                            break;
                    }
            }
    }
    rs.status();
EOF

This however doesn't break out of the infinite loop. And I want to check every 30 seconds. How do I do that?

Answer 1

mongo --host ${other_host} ${ssl_mode} << EOF
  while (rs.status().members.every(e => e.stateStr != "SECONDARY")) {
    sleep(1000);  
  }
  rs.status();
  EOF

Note that I also added a sleep , to avoid busy waiting.

---

Update 1: If your mongo version is a little older, then you may not be able to use arrow functions and will need to spell it out like this:

  while (rs.status().members.every(function(e) { return e.stateStr != "SECONDARY"; })) {