Build ansible inventory from SSH config

build_inventory.sh

#!/usr/bin/env bash
keybasepath="$HOME/.ssh/"
cat $HOME/.ssh/config | awk -v RS= -v FS=\\n -v IGNORECASE=1 -v keybasepath="$keybasepath" '
    {
        ip = ""
        alias = ""
        id_file = ""
        username = ""
        port = ""
        result = ""
        for (j = 1; j <= NF; ++j) {
            split($j, tmp, " ")
            if (tmp[1] == "Host") { alias = tmp[2] }
            if (tmp[1] == "Hostname") { ip = tmp[2] }
            if (tmp[1] == "IdentityFile") { id_file = substr(tmp[2], 8) }
            if (tmp[1] == "User") { username = tmp[2] }
            if (tmp[1] == "Port") { port = tmp[2] }
        }
        if (ip || alias && alias != "*") {
            result = sprintf("%-35s ansible_host=%-25s ",alias,ip)
            if (username) result = sprintf("%s ansible_user=%-20s",result,username)
            if (port) result = sprintf("%s ansible_port=%-5s",result,port)
            if (id_file) result = sprintf("%s ansible_ssh_private_key_file=%s%s",result,keybasepath,id_file)
            printf "%s\n",result
        }
    }
' > hosts.txt