feat(cmd): add output matcher plugin

This commit is contained in:
Emmanuel BENOîT 2024-07-20 20:47:42 +02:00
parent 1f9be057b6
commit 09df5aa44e
Signed by: Emmanuel BENOîT
SSH key fingerprint: SHA256:l7PFUUF5TCDsvYeQC9OnTNz08dFY7Fvf4Hv3neIqYpg
3 changed files with 412 additions and 0 deletions

95
cmd/matches/cmdline.go Normal file
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@ -0,0 +1,95 @@
package matches // import nocternity.net/gomonop/cmd/matches
import (
"context"
"regexp"
"strings"
"time"
"github.com/karrick/golf"
"nocternity.net/gomonop/pkg/perfdata"
)
// pluginFlags represent command line flags that have been parsed.
type pluginFlags struct {
isFile bool // Are we reading from a file?
dataSource string // The file or command to read from
timeout time.Duration // A timeout for the command, or 0 to disable
matches []matchConfig // Configuration for the matches to check
strict bool // Reject lines that don't match anything
}
// matchConfig is the configuration for a single match to check.
type matchConfig struct {
isRegexp bool // Are we checking against a regular expression?
matchString string // The string or regexp to match
compiledRe *regexp.Regexp // The compiled regexp
warn *perfdata.Range // Warning range
crit *perfdata.Range // Critical range
}
// parseArguments parses command line arguments for the plugin.
func (p *pluginFlags) parseArguments() {
golf.BoolVarP(&p.isFile, 'f', "is-file", false, "Are we reading from a file?")
golf.StringVarP(&p.dataSource, 's', "source", "", "The file or command to read from")
golf.DurationVarP(&p.timeout, 'T', "timeout", 0, "A timeout for the command, or 0 to disable")
golf.BoolVarP(&p.strict, 'S', "strict", false, "Reject lines that do not match anything")
isRegexp := golf.BoolP('R', "no-regexp", true, "Following match argument will be a basic string")
golf.BoolVarP(isRegexp, 'r', "regexp", false, "Following match argument will be a regexp")
var wRange *perfdata.Range
golf.StringFuncP('w', "warn", "", "Warning range, in Nagios-compatible format", func(s string) error {
locRange, err := perfdata.ParseRange(s)
if err == nil {
wRange = locRange
}
return err
})
golf.BoolFuncP('W', "no-warn", false, "Clear warning range", func(bool) error {
wRange = nil
return nil
})
var cRange *perfdata.Range
golf.StringFuncP('c', "critical", "", "Critical range, in Nagios-compatible format", func(s string) error {
locRange, err := perfdata.ParseRange(s)
if err == nil {
cRange = locRange
}
return err
})
golf.BoolFuncP('C', "no-critical", false, "Clear warning range", func(bool) error {
cRange = nil
return nil
})
golf.StringFuncP('m', "match", "", "Match string", func(s string) error {
p.matches = append(p.matches, matchConfig{
isRegexp: *isRegexp,
matchString: s,
warn: wRange,
crit: cRange,
})
return nil
})
golf.Parse()
}
// makeContext generates a context based on the timeout, if one is set.
func (p *pluginFlags) makeContext() (context.Context, context.CancelFunc) {
if p.timeout == 0 {
return context.Background(), func() {}
}
return context.WithTimeout(context.Background(), p.timeout)
}
// matches check if the specified string matches a configuration.
func (p *matchConfig) matches(s string) bool {
if p.isRegexp {
return p.compiledRe.MatchString(s)
}
return strings.Contains(s, p.matchString)
}

315
cmd/matches/plugin.go Normal file
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@ -0,0 +1,315 @@
// The matches package contains the implementation of the `check_output_matches`
// plugin, which can be used to run an arbitrary command and check its output
// against various patterns. It can also be configured to do the same on an
// arbitrary file.
package matches // import nocternity.net/gomonop/cmd/matches
import (
"bufio"
"context"
"fmt"
"io"
"os"
"os/exec"
"regexp"
"strconv"
"strings"
"nocternity.net/gomonop/pkg/perfdata"
"nocternity.net/gomonop/pkg/plugin"
"nocternity.net/gomonop/pkg/results"
"nocternity.net/gomonop/pkg/status"
)
// Program data for the string matches plugin.
type matchesPlugin struct {
pluginFlags // Flags from the command line
results *results.Results // Plugin output state
counters []int // Counters for each match
unmatchedLines int // Number of lines that didn't match anything
}
// Initialise the plugin.
func NewPlugin() plugin.Plugin {
pluginInst := &matchesPlugin{
results: results.New("String matches counter"),
}
pluginInst.parseArguments()
return pluginInst
}
// Return the program's output value.
func (pluginInst *matchesPlugin) Results() *results.Results {
return pluginInst.results
}
// Check the values that were specified from the command line. Returns true
// if the arguments made sense.
func (pluginInst *matchesPlugin) CheckArguments() bool {
if pluginInst.dataSource == "" {
pluginInst.results.SetState(status.StatusUnknown, "no data source specified")
return false
}
if !pluginInst.strict && len(pluginInst.matches) == 0 {
pluginInst.results.SetState(status.StatusUnknown, "would match anything")
return false
}
for index := range pluginInst.matches {
if pluginInst.matches[index].matchString == "" {
pluginInst.results.SetState(status.StatusUnknown, "empty match string")
pluginInst.results.AddLinef("(At match %d)", index+1)
return false
}
if pluginInst.matches[index].isRegexp {
rexp, err := regexp.Compile(pluginInst.matches[index].matchString)
if err != nil {
pluginInst.results.SetState(status.StatusUnknown, "Invalid regular expression")
pluginInst.results.AddLine(err.Error())
pluginInst.results.AddLinef("(At match %d)", index+1)
return false
}
pluginInst.matches[index].compiledRe = rexp
}
}
return true
}
// readFromFile starts a goroutine that reads from the file and sends each line
// to the dataPipe.
func (pluginInst *matchesPlugin) readFromFile(ctx context.Context, donePipe chan error, dataPipe chan string) {
go func() {
file, err := os.Open(pluginInst.dataSource)
if err != nil {
donePipe <- err
return
}
defer file.Close()
scanner := bufio.NewScanner(file)
for scanner.Scan() {
select {
case <-ctx.Done():
donePipe <- ctx.Err()
return
case dataPipe <- scanner.Text():
}
}
donePipe <- scanner.Err()
}()
}
// startPipeCopy starts a goroutine that copies data from the reader to the
// dataPipe.
func startPipeCopy(reader io.Reader, dataPipe chan string) (aborter chan struct{}, readError chan error) {
aborter = make(chan struct{})
readError = make(chan error)
go func() {
scanner := bufio.NewScanner(reader)
for scanner.Scan() {
select {
case <-aborter:
return
case dataPipe <- scanner.Text():
}
}
readError <- scanner.Err()
}()
return
}
// readFromProgram starts a goroutine that controls the program, sending lines
// from both stderr and stdout to the dataPipe.
func (pluginInst *matchesPlugin) readFromProgram(ctx context.Context, donePipe chan error, dataPipe chan string) {
go func() {
cmd := exec.Command(pluginInst.dataSource) //nolint:gosec // Command is in fact user-provided
stdout, err := cmd.StdoutPipe()
if err != nil {
donePipe <- err
return
}
stderr, err := cmd.StderrPipe()
if err != nil {
donePipe <- err
return
}
if err := cmd.Start(); err != nil {
donePipe <- err
return
}
outAborter, outReadError := startPipeCopy(stdout, dataPipe)
errAborter, errReadError := startPipeCopy(stderr, dataPipe)
defer func() {
_ = stdout.Close()
_ = stderr.Close()
close(outAborter)
close(errAborter)
close(outReadError)
close(errReadError)
}()
abort := func(err error) {
outAborter <- struct{}{}
errAborter <- struct{}{}
_ = cmd.Process.Kill()
donePipe <- err
}
errComplete := false
outComplete := false
for !(errComplete && outComplete) {
select {
case <-ctx.Done():
abort(ctx.Err())
return
case err := <-outReadError:
if err != nil {
abort(err)
return
}
outComplete = true
case err := <-errReadError:
if err != nil {
abort(err)
return
}
errComplete = true
}
}
donePipe <- cmd.Wait()
}()
}
// startReading starts reading data from either a file or a program.
func (pluginInst *matchesPlugin) startReading(ctx context.Context, donePipe chan error, dataPipe chan string) {
if pluginInst.isFile {
pluginInst.readFromFile(ctx, donePipe, dataPipe)
} else {
pluginInst.readFromProgram(ctx, donePipe, dataPipe)
}
}
// processLine processes a single line obtained from the program or file.
func (pluginInst *matchesPlugin) processLine(line string) {
hadMatch := false
for index := range pluginInst.matches {
if pluginInst.matches[index].matches(line) {
pluginInst.counters[index]++
hadMatch = true
}
}
if !hadMatch {
pluginInst.unmatchedLines++
}
}
// processData processes data from either the program or the file.
func (pluginInst *matchesPlugin) processData() error {
ctx, cancel := pluginInst.makeContext()
defer cancel()
donePipe := make(chan error)
dataPipe := make(chan string)
pluginInst.startReading(ctx, donePipe, dataPipe)
defer func() {
close(donePipe)
close(dataPipe)
}()
for {
select {
case line := <-dataPipe:
pluginInst.processLine(line)
case err := <-donePipe:
return err
}
}
}
// checkResults checks the various counters against their configured thresholds,
// and the strict mode failure count.
func (pluginInst *matchesPlugin) checkResults(readError error) {
nWarns, nCrits, nUnknowns := 0, 0, 0
for index := range pluginInst.counters {
config := &pluginInst.matches[index]
var nature string
if config.isRegexp {
nature = "regexp"
} else {
nature = "substring"
}
label := fmt.Sprintf("#%2d : %s %s", index+1, nature, config.matchString)
value := strconv.Itoa(pluginInst.counters[index])
pdat := perfdata.New(label, perfdata.UomNone, value)
pdat.SetWarn(config.warn)
pdat.SetCrit(config.crit)
pluginInst.results.AddPerfData(pdat)
switch pdat.GetStatus() {
case status.StatusCritical:
nCrits++
case status.StatusWarning:
nWarns++
case status.StatusUnknown:
nUnknowns++
}
}
umlPdat := perfdata.New("unmatched", perfdata.UomNone, strconv.Itoa(pluginInst.unmatchedLines))
if pluginInst.strict {
umlPdat.SetCrit(perfdata.RangeMinMax("~", "0"))
}
switch umlPdat.GetStatus() {
case status.StatusCritical:
nCrits++
}
pluginInst.results.AddPerfData(umlPdat)
problems := []string{}
if nCrits > 0 {
problems = append(problems, fmt.Sprintf("%d value(s) critical", nCrits))
}
if nWarns > 0 {
problems = append(problems, fmt.Sprintf("%d value(s) warning", nWarns))
}
if nUnknowns > 0 {
problems = append(problems, fmt.Sprintf("%d value(s) unknown", nUnknowns))
}
if len(problems) == 0 {
problems = append(problems, "No match errors")
}
if readError != nil {
pluginInst.results.AddLinef("Error while reading data: %s", readError.Error())
nUnknowns++
}
var finalStatus status.Status
switch {
case nCrits > 0:
finalStatus = status.StatusCritical
case nWarns > 0:
finalStatus = status.StatusWarning
case nUnknowns > 0:
finalStatus = status.StatusUnknown
default:
finalStatus = status.StatusOK
}
pluginInst.results.SetState(finalStatus, strings.Join(problems, ", "))
}
// Run the check.
func (pluginInst *matchesPlugin) RunCheck() {
pluginInst.counters = make([]int, len(pluginInst.matches))
err := pluginInst.processData()
pluginInst.checkResults(err)
}

View file

@ -5,6 +5,7 @@ import (
"os"
"path/filepath"
"nocternity.net/gomonop/cmd/matches"
"nocternity.net/gomonop/cmd/sslcert"
"nocternity.net/gomonop/cmd/zoneserial"
"nocternity.net/gomonop/pkg/plugin"
@ -14,6 +15,7 @@ import (
var (
plugins map[string]plugin.Builder = map[string]plugin.Builder{
"check_output_matches": matches.NewPlugin,
"check_ssl_certificate": sslcert.NewProgram,
"check_zone_serial": zoneserial.NewProgram,
}