Shell dynamic variable as condition inside AWK - if-statement

Question

I have a sh (POSIX) script where I'm trying to choose a host from a list of hosts (SSH), this list have some interesting info along the hosts names, like free memory available, users already connected... I want the user of my script to choose what characteristics should have the script in consideration to choose a suitable host from said list.
As this characteristics are optional, what I thought was to build a conditional statment in a shell variable (just text) based in the options the user have chosen. Then, pass this variable to AWK to extract those suitable hosts and choose one of them randomly. By the moment, saild statment or FILTER could look like this:
FILTER='$6 <=MAXUSERS && $7 <=MAXUSERS'
FILTER='$6 <=MAXUSERS && $7 <=MAXUSERS && $9 >=10'
FILTER='$6 <=MAXUSERS && $7 <=MAXUSERS && $9 >=10 && $11 >=8'
($X are just positional parameters as characteristics of the host, I know theirs positions and should not change as long as the HTML source doesnt change either) I build those statments with this piece of code:
setUpFilter(){
FILTER='$6 <=MAXUSERS && $7 <=MAXUSERS'
if [ -n "$CPUNUM" ]; then
FILTER="${FILTER} && \$9 >=$CPUNUM"
fi
if [ -n "$FREEMEM" ]; then
FILTER="${FILTER} && \$12 >=$FREEMEM"
fi
}
Once the statment is built, I use this:
filterHosts(){
setUpFilter
for HOST in $(echo "$AVAILABLEHOSTS"); do # $AVAILABLEHOSTS is a list with only the hosts names
HOSTDATA=$(echo "$REPORTCLEAN" | egrep -A 11 "$HOST") # Report clean is a list of hosts and its data extracted from an HTML file
FILTEREDHOSTS=${FILTEREDHOSTS}$(echo $HOSTDATA | awk -v FILTER="$FILTER" -v MAXUSERS=5 '{
if (FILTER)
print $1 "\\n"
}')
done
}
However this does not work as expected since the "filter" seems like doing nothing, as all the hosts are stored in $FILTEREDHOSTS like the condition was true in all the iterations (And I'm not sure why), however when I manually set the condition inside the AWK script, the "filter" works as expected:
filterHosts(){
setUpFilter
for HOST in $(echo "$AVAILABLEHOSTS"); do # $AVAILABLEHOSTS is a list with only the hosts names
HOSTDATA=$(echo "$REPORTCLEAN" | egrep -A 11 "$HOST") # Report clean is a list of hosts and its data extracted from an HTML file
FILTEREDHOSTS=${FILTEREDHOSTS}$(echo $HOSTDATA | awk -v MAXUSERS=5 '{
if ($6 <=MAXUSERS && $7 <=MAXUSERS && $9 >=10)
print $1 "\\n"
}')
done
}
$HOSTDATA looks like this, btw: HOSTNAME PARAM2 PARAM3 ... PARAM12, so I want to retrieve $1 (The host name) based on some of the params matching some values.
I know that this second piece of code works because I checked the list manually after executing it.
I've tried to make AWK print FILTER, and apparently the statment is correct since it prints just like the firsts examples I wrote above, with nothing expanded or unexpected things, literally like the examples.
I'm not that good in AWK so I have no idea what could be happening, I'm not even sure if this is an issue of AWK at all. By the other hand, I'm wondering if this is the best approach I could get for what I'm trying to accomplish.
Thanks in advance.
UPDATE
As some users suggested, I moved the 'filter' built to the awk script itself, so I ended up with this:
filterHosts(){
for HOST in $(echo "$AVAILABLEHOSTS"); do
HOSTDATA=$(echo "$REPORTCLEAN" | egrep -A 11 "$HOST")
FILTEREDHOSTS=${FILTEREDHOSTS}$(echo $HOSTDATA | awk -v cpunum="$CPUNUM" -v freemem="$FREEMEM" -v MAXUSERS="$1" '{
filter = $6 <=MAXUSERS && $7 <=MAXUSERS
if (length(cpunum) != 0)
filter = filter && $9 >= cpunum
if (length(freemem) != 0)
filter = filter && $12 >= freemem
if (filter)
print $1 "\\n"
}')
done
}
Apparently this works with no issues at first glance, so I consider this issue 'semi-solved' since I not sure why the previous code did not work, but I have a different piece of code that works.