/
parser.go
166 lines (143 loc) · 4.8 KB
/
parser.go
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package haproxy
import (
"fmt"
"io/ioutil"
"net/http"
"net/url"
"strings"
"time"
"github.com/github/freno/pkg/base"
"github.com/patrickmn/go-cache"
)
var csvCache = cache.New(time.Second, time.Second)
var HAProxyEmptyBody error = fmt.Errorf("Haproxy GET error: empty body")
var HAProxyEmptyStatus error = fmt.Errorf("Haproxy CSV parsing error: no lines found")
var HAProxyPartialStatus error = fmt.Errorf("Haproxy CSV parsing error: only got partial file")
var HAProxyMissingPool error = fmt.Errorf("Haproxy CSV parsing: pool not found")
var HAProxyAllUpHostsTransitioning error = fmt.Errorf("Haproxy: all host marked as UP are in transition. HAProxy is likely reloading")
var HAProxyAllHostsTransitioning error = fmt.Errorf("Haproxy: all hosts are in transition. HAProxy is likely reloading")
var MaxHTTPGetConcurrency = 2
var httpGetConcurrencyChan = make(chan bool, MaxHTTPGetConcurrency)
var httpClient *http.Client
func init() {
httpClient = base.SetupHttpClient(0)
}
// parseHeader parses the HAPRoxy CSV header, which lists column names.
// Returned is a header-to-index map
func parseHeader(header string) (tokensMap map[string]int) {
tokensMap = map[string]int{}
header = strings.TrimLeft(header, "#")
header = strings.TrimSpace(header)
tokens := strings.Split(header, ",")
for i, token := range tokens {
tokensMap[token] = i
}
return tokensMap
}
// Simple utility function to split CSV lines
func parseLines(csv string) []string {
return strings.Split(csv, "\n")
}
func ParseStatus(fullStatus string) (status BackendHostStatus, isTransitioning bool) {
// status can show up as:
// `UP`
// `UP 1/2` (transitioning)
// `NOLB`
// `DOWN`
// `DOWN (agent)`
// `no check`
// etc. See https://github.com/haproxy/haproxy/blob/a5de024d42c4113fc6e189ea1d0ba6335219e151/src/dumpstats.c#L4117-L4129
if ToBackendHostStatus(fullStatus) == StatusNoCheck {
return StatusNoCheck, isTransitioning
}
statusTokens := strings.Split(fullStatus, " ")
isTransitioning = (len(statusTokens) > 1 && strings.Contains(statusTokens[1], "/"))
return ToBackendHostStatus(statusTokens[0]), isTransitioning
}
// ParseHosts reads HAProxy CSV lines and returns lists of hosts participating in the given pool (backend)
// Returned are all non-disabled hosts in given backend. Thus, a NOLB is skipped; any UP or DOWN hosts are returned.
// Such list indicates the hosts which can be expected to be active, which is then the list freno will probe.
func ParseHosts(csvLines []string, poolName string) (backendHosts [](*BackendHost), err error) {
if len(csvLines) < 1 {
return backendHosts, HAProxyEmptyStatus
}
if len(csvLines) == 1 {
return backendHosts, HAProxyPartialStatus
}
var tokensMap map[string]int
poolFound := false
countHosts := 0
countUpHosts := 0
countTransitioningHosts := 0
countTransitioningUpHosts := 0
for i, line := range csvLines {
if i == 0 {
tokensMap = parseHeader(csvLines[0])
continue
}
tokens := strings.Split(line, ",")
if tokens[tokensMap["pxname"]] == poolName {
poolFound = true
if host := tokens[tokensMap["svname"]]; host != "BACKEND" && host != "FRONTEND" {
countHosts++
status, isTransitioning := ParseStatus(tokens[tokensMap["status"]])
backendHosts = append(backendHosts, NewBackendHost(host, status, isTransitioning))
if isTransitioning {
countTransitioningHosts++
}
if status == StatusUp {
countUpHosts++
if isTransitioning {
countTransitioningUpHosts++
}
}
}
}
}
if !poolFound {
return backendHosts, HAProxyMissingPool
}
if countTransitioningHosts == countHosts && countHosts > 0 {
return backendHosts, HAProxyAllHostsTransitioning
}
if countTransitioningUpHosts == countUpHosts && countUpHosts > 0 {
return backendHosts, HAProxyAllUpHostsTransitioning
}
return backendHosts, nil
}
// ParseCsvHosts reads HAProxy CSV text and returns lists of hosts participating in the given pool (backend).
// See comment for ParseHosts
func ParseCsvHosts(csv string, poolName string) (backendHosts [](*BackendHost), err error) {
csvLines := parseLines(csv)
return ParseHosts(csvLines, poolName)
}
func toCSVUrl(u url.URL) *url.URL {
u.Path = fmt.Sprintf("%s;csv;norefresh", u.Path)
return &u
}
// Read will read HAProxy URI and return with the CSV text
func Read(u *url.URL) (csv string, err error) {
httpGetConcurrencyChan <- true
defer func() { <-httpGetConcurrencyChan }()
haproxyUrl := toCSVUrl(*u).String()
if cachedCSV, found := csvCache.Get(haproxyUrl); found {
return cachedCSV.(string), nil
}
resp, err := httpClient.Get(haproxyUrl)
if resp != nil {
defer resp.Body.Close()
}
if err != nil {
return "", err
}
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return "", err
}
csv = string(body)
if csv == "" {
return "", HAProxyEmptyBody
}
csvCache.Set(haproxyUrl, csv, cache.DefaultExpiration)
return csv, nil
}