ssh-wait

#!/bin/bash

# A script to wait for a list of ssh servers to come up
# Shamelessly stolen from https://serverfault.com/a/995377/254476

SCRIPT_DIR=$(dirname "${BASH_SOURCE[0]}")
# shellcheck disable=SC1090
. "$SCRIPT_DIR/poshlib/poshlib.sh" || exit 1
use strict
use utils

[[ "${1:-}" ]] || die 1 "Usage: $0 <host>[:<port>][,<host>[:<port]][,...] [<retries> [<retry_wait>]]"
HOSTS=$(tr , " " <<< "$1")

retries=${2:-30}
retry_wait=${3:-10}

for host in $HOSTS; do
  port=${host#*:}
  host=${host%%:*}
  [[ "$port" && "$port" != "$host" ]] || port=22

  result=1 # 0 upon success
  while :; do
    status=$(
        set +e
        # Disable all forms of authentication as we don't want to waste time
        SSH_AUTH_SOCK=/dev/null ssh -i /dev/null -l "" -o BatchMode=yes -o ConnectTimeout=5 "${host}" -P "${port}" echo ok 2>&1
        echo "result=$?"
    )
    result="${status#*result=}"
    if [[ $result -eq 0 ]]; then
        # this is not really expected but it could happen
        echo "logged in anonymously to $host"
        break
    fi
    if [[ $result -eq 255 ]]; then
        # connection refused also gets you here
        if [[ $status == *"Permission denied"* || $status == *"Host key verification failed"* ]] ; then
            # If we get any kind of authorisation error it counts as success
            echo "connected to $host"
            break
        fi
    fi
    retries=$((retries-1))
    if [[ $retries -eq 0 ]]; then
        die 2 "Too many retries; aborting"
    fi
    echo -n "."
    sleep "$retry_wait"
  done
done
echo
exit 0