open-consul/sdk/freeport/ephemeral_linux.go
R.B. Boyer 5c5f21088c sdk: add freelist tracking and ephemeral port range skipping to freeport
This should cut down on test flakiness.

Problems handled:

- If you had enough parallel test cases running, the former circular
approach to handling the port block could hand out the same port to
multiple cases before they each had a chance to bind them, leading to
one of the two tests to fail.

- The freeport library would allocate out of the ephemeral port range.
This has been corrected for Linux (which should cover CI).

- The library now waits until a formerly-in-use port is verified to be
free before putting it back into circulation.
2019-09-17 14:30:43 -05:00

37 lines
734 B
Go

//+build linux
package freeport
import (
"fmt"
"os/exec"
"regexp"
"strconv"
)
const ephemeralPortRangeSysctlKey = "net.ipv4.ip_local_port_range"
var ephemeralPortRangePatt = regexp.MustCompile(`^\s*(\d+)\s+(\d+)\s*$`)
func getEphemeralPortRange() (int, int, error) {
cmd := exec.Command("sysctl", "-n", ephemeralPortRangeSysctlKey)
out, err := cmd.Output()
if err != nil {
return 0, 0, err
}
val := string(out)
m := ephemeralPortRangePatt.FindStringSubmatch(val)
if m != nil {
min, err1 := strconv.Atoi(m[1])
max, err2 := strconv.Atoi(m[2])
if err1 == nil && err2 == nil {
return min, max, nil
}
}
return 0, 0, fmt.Errorf("unexpected sysctl value %q for key %q", val, ephemeralPortRangeSysctlKey)
}