forked from wrenn/wrenn
pptx704
9acdbb5ae9
Samples /proc/{fc_pid}/stat (CPU%), /proc/{fc_pid}/status (VmRSS), and
stat() on CoW files at 500ms intervals per running sandbox. Three tiered
ring buffers downsample into 30s and 5min averages for 10min/2h/24h
retention. Metrics are flushed to DB on pause (all tiers) and destroy
(24h only). New GetSandboxMetrics and FlushSandboxMetrics RPCs on the
host agent, proxied through GET /v1/sandboxes/{id}/metrics?range= on
the control plane. Returns live data for running sandboxes, DB data for
paused, and 404 for stopped.
106 lines
3.3 KiB
Go
106 lines
3.3 KiB
Go
package sandbox
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import (
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"fmt"
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"os"
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"strconv"
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"strings"
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"syscall"
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)
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// findChildPID reads the direct child PID of a given parent process.
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// The Firecracker process is a direct child of the unshare wrapper because
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// the init script uses `exec ip netns exec ... firecracker`, which replaces
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// bash with ip-netns-exec, which in turn execs firecracker — same PID,
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// direct child of unshare.
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func findChildPID(parentPID int) (int, error) {
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path := fmt.Sprintf("/proc/%d/task/%d/children", parentPID, parentPID)
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data, err := os.ReadFile(path)
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if err != nil {
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return 0, fmt.Errorf("read children: %w", err)
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}
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fields := strings.Fields(string(data))
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if len(fields) == 0 {
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return 0, fmt.Errorf("no child processes found for PID %d", parentPID)
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}
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pid, err := strconv.Atoi(fields[0])
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if err != nil {
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return 0, fmt.Errorf("parse child PID %q: %w", fields[0], err)
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}
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return pid, nil
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}
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// cpuStat holds raw CPU jiffies read from /proc/{pid}/stat.
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type cpuStat struct {
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utime uint64
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stime uint64
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}
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// readCPUStat reads user and system CPU jiffies from /proc/{pid}/stat.
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// Fields 14 (utime) and 15 (stime) are 1-indexed in the man page;
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// after splitting on space, they are at indices 13 and 14.
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func readCPUStat(pid int) (cpuStat, error) {
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path := fmt.Sprintf("/proc/%d/stat", pid)
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data, err := os.ReadFile(path)
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if err != nil {
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return cpuStat{}, fmt.Errorf("read stat: %w", err)
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}
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// /proc/{pid}/stat format: pid (comm) state fields...
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// The comm field may contain spaces and parens, so find the last ')' first.
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content := string(data)
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idx := strings.LastIndex(content, ")")
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if idx < 0 {
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return cpuStat{}, fmt.Errorf("malformed /proc/%d/stat: no closing paren", pid)
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}
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// After ")" there is " state field3 field4 ... fieldN"
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// field1 after ')' is state (index 0), utime is field 11, stime is field 12
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// (0-indexed from after the closing paren).
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fields := strings.Fields(content[idx+2:])
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if len(fields) < 13 {
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return cpuStat{}, fmt.Errorf("malformed /proc/%d/stat: too few fields (%d)", pid, len(fields))
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}
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utime, err := strconv.ParseUint(fields[11], 10, 64)
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if err != nil {
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return cpuStat{}, fmt.Errorf("parse utime: %w", err)
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}
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stime, err := strconv.ParseUint(fields[12], 10, 64)
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if err != nil {
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return cpuStat{}, fmt.Errorf("parse stime: %w", err)
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}
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return cpuStat{utime: utime, stime: stime}, nil
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}
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// readMemRSS reads VmRSS from /proc/{pid}/status and returns bytes.
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func readMemRSS(pid int) (int64, error) {
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path := fmt.Sprintf("/proc/%d/status", pid)
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data, err := os.ReadFile(path)
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if err != nil {
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return 0, fmt.Errorf("read status: %w", err)
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}
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for _, line := range strings.Split(string(data), "\n") {
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if strings.HasPrefix(line, "VmRSS:") {
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fields := strings.Fields(line)
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if len(fields) < 2 {
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return 0, fmt.Errorf("malformed VmRSS line")
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}
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kb, err := strconv.ParseInt(fields[1], 10, 64)
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if err != nil {
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return 0, fmt.Errorf("parse VmRSS: %w", err)
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}
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return kb * 1024, nil
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}
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}
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return 0, fmt.Errorf("VmRSS not found in /proc/%d/status", pid)
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}
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// readDiskAllocated returns the actual allocated bytes (not apparent size)
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// of the file at path. This uses stat's block count × 512.
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func readDiskAllocated(path string) (int64, error) {
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var stat syscall.Stat_t
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if err := syscall.Stat(path, &stat); err != nil {
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return 0, fmt.Errorf("stat %s: %w", path, err)
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}
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return stat.Blocks * 512, nil
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}
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