fix(scheduler): standardize metric descriptor label key from node to node_name - #2343

#!/bin/bash
set -euo pipefail

# Verify the resolved client_golang version and Desc.String() representation.
rg -n -C2 'github.com/prometheus/client_golang' go.mod go.sum
curl -fsSL https://raw.githubusercontent.com/prometheus/client_golang/v1.24.1/prometheus/desc.go |
  rg -n -A10 'func \(d \*Desc\) String'

#!/bin/bash
set -euo pipefail

# Inspect the metric descriptor output format and test predicates without running repository code.
FILE="cmd/scheduler/metrics_test.go"
if [ -f "$FILE" ]; then
  echo "== file lines 120-225 =="
  cat -n "$FILE" | sed -n '120,225p'
fi

echo "== relevant Prometheus Desc.String format examples =="
python3 - <<'PY'
# Directly model Prometheus github.com/prometheus/client_golang v1.24.1 Desc.String() variableLabels formatting.
# The implementation appends names with fmt.Sprintf("%s=%q", name, ...) joined by ", ".
def variable_labels_str(names):
    return ", ".join(f'{{name={n!r}}}' for n in names)

cases = [
    [],
    ["node"],
    ["node_name"],
    ["node_name", "node"],
    ["node", "node_name"],
    ["node", "other"],
]
for names in cases:
    s = f"Desc(dname=\"dname\", fqName: \"fqName\", help: \"\", variableLabels: {variable_labels_str(names)}, constLabelPairs: []constLabelPair, err: )"
    print("names=", names)
    print("contains_variableLabels: [node ", "variableLabels: [node " in s)
    print("contains_variableLabels: [node,", "variableLabels: [node," in s)
    print("contains_variableLabels: {node}", "variableLabels: " in s and "{node}" in s)
    print("contains node boundaries", any(tok in s for tok in ['{node}', ',node,']))
    print("contains exact node_name node substring", "node_name" in s and "node" in s)
    print()
PY

echo "== all occurrences of the old-label predicate =="
rg -n "variableLabels: \\[node" cmd/scheduler/metrics_test.go

#!/bin/bash
set -euo pipefail

python3 - <<'PY'
import urllib.request
url = "https://raw.githubusercontent.com/prometheus/client_golang/v1.24.1/prometheus/desc.go"
text = urllib.request.urlopen(url).read().decode()
start = text.find('func (d *Desc) String()')
end = text.find('\nfunc ', start + 1)
print(text[start:end if end != -1 else len(text)])
PY

echo "== raw URL source around variableLabels formatting =="
python3 - <<'PY'
import urllib.request
text = urllib.request.urlopen("https://raw.githubusercontent.com/prometheus/client_golang/v1.24.1/prometheus/desc.go").read().decode()
for i, line in enumerate(text.splitlines(), 1):
    if 'variableLabels' in line or 'names' in line:
        print(f"{i}: {line}")
PY

#!/bin/bash
set -euo pipefail

GOCACHE="$(go env GOCACHE 2>/dev/null || true)"
echo "GOCACHE=$GOCACHE"

find "$GOCACHE" \
  -path '*prometheus/client_golang@v1.24.1/prometheus/desc.go' \
  -type f 2>/dev/null | while read -r f; do
    echo "== $f =="
    sed -n '200,235p' "$f"
done

echo "== local module cache occurrences across downloaded tags =="
find "$GOCACHE" \
  -path '*/prometheus/client_golang@*/prometheus/desc.go' \
  -type f 2>/dev/null | while read -r f; do
    echo "-- $f --"
    rg -n 'variableLabels:|variableLabels\.names|variableLabels: \{' "$f" || true
done

echo "== deterministic model comparison =="
# Use the exact formatting from the v1.24.1 source snippet if it uses {name}.
declare -a inputs=("node" "node_name" "node_name,node" "node,node_name" "node,other")
for labels in "${inputs[@]}"; do
  s="Desc{fqName: \"hami_x\", help: \"\", variableLabels: {$labels}, constLabels: {}, constLabelPairs: []constLabelPair, err: }"
  echo "labels=$labels"
  echo "  contains variableLabels: [node space -> ${s#*(contains variableLabels: [node space -> *false, skipped)}"; if echo "$s" | grep -q 'variableLabels: \[node '; then echo "  bracket-space true"; else echo "  bracket-space false"; fi
  echo "  contains variableLabels: [node comma -> "; if echo "$s" | grep -q 'variableLabels: \[node,'; then echo "true"; else echo "false"; fi; echo
done