148 lines
4.2 KiB
Go
148 lines
4.2 KiB
Go
/*
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Copyright 2020 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package rest
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import (
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"fmt"
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"io"
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"net/http"
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"sync"
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"k8s.io/klog/v2"
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"k8s.io/apimachinery/pkg/util/net"
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)
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// WarningHandler is an interface for handling warning headers
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type WarningHandler interface {
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// HandleWarningHeader is called with the warn code, agent, and text when a warning header is countered.
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HandleWarningHeader(code int, agent string, text string)
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}
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var (
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defaultWarningHandler WarningHandler = WarningLogger{}
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defaultWarningHandlerLock sync.RWMutex
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)
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// SetDefaultWarningHandler sets the default handler clients use when warning headers are encountered.
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// By default, warnings are logged. Several built-in implementations are provided:
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// - NoWarnings suppresses warnings.
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// - WarningLogger logs warnings.
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// - NewWarningWriter() outputs warnings to the provided writer.
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func SetDefaultWarningHandler(l WarningHandler) {
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defaultWarningHandlerLock.Lock()
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defer defaultWarningHandlerLock.Unlock()
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defaultWarningHandler = l
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}
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func getDefaultWarningHandler() WarningHandler {
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defaultWarningHandlerLock.RLock()
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defer defaultWarningHandlerLock.RUnlock()
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l := defaultWarningHandler
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return l
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}
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// NoWarnings is an implementation of WarningHandler that suppresses warnings.
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type NoWarnings struct{}
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func (NoWarnings) HandleWarningHeader(code int, agent string, message string) {}
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// WarningLogger is an implementation of WarningHandler that logs code 299 warnings
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type WarningLogger struct{}
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func (WarningLogger) HandleWarningHeader(code int, agent string, message string) {
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if code != 299 || len(message) == 0 {
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return
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}
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klog.Warning(message)
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}
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type warningWriter struct {
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// out is the writer to output warnings to
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out io.Writer
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// opts contains options controlling warning output
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opts WarningWriterOptions
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// writtenLock guards written and writtenCount
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writtenLock sync.Mutex
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writtenCount int
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written map[string]struct{}
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}
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// WarningWriterOptions controls the behavior of a WarningHandler constructed using NewWarningWriter()
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type WarningWriterOptions struct {
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// Deduplicate indicates a given warning message should only be written once.
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// Setting this to true in a long-running process handling many warnings can result in increased memory use.
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Deduplicate bool
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// Color indicates that warning output can include ANSI color codes
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Color bool
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}
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// NewWarningWriter returns an implementation of WarningHandler that outputs code 299 warnings to the specified writer.
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func NewWarningWriter(out io.Writer, opts WarningWriterOptions) *warningWriter {
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h := &warningWriter{out: out, opts: opts}
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if opts.Deduplicate {
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h.written = map[string]struct{}{}
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}
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return h
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}
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const (
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yellowColor = "\u001b[33;1m"
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resetColor = "\u001b[0m"
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)
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// HandleWarningHeader prints warnings with code=299 to the configured writer.
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func (w *warningWriter) HandleWarningHeader(code int, agent string, message string) {
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if code != 299 || len(message) == 0 {
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return
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}
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w.writtenLock.Lock()
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defer w.writtenLock.Unlock()
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if w.opts.Deduplicate {
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if _, alreadyWritten := w.written[message]; alreadyWritten {
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return
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}
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w.written[message] = struct{}{}
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}
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w.writtenCount++
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if w.opts.Color {
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fmt.Fprintf(w.out, "%sWarning:%s %s\n", yellowColor, resetColor, message)
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} else {
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fmt.Fprintf(w.out, "Warning: %s\n", message)
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}
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}
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func (w *warningWriter) WarningCount() int {
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w.writtenLock.Lock()
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defer w.writtenLock.Unlock()
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return w.writtenCount
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}
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func handleWarnings(headers http.Header, handler WarningHandler) []net.WarningHeader {
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if handler == nil {
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handler = getDefaultWarningHandler()
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}
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warnings, _ := net.ParseWarningHeaders(headers["Warning"])
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for _, warning := range warnings {
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handler.HandleWarningHeader(warning.Code, warning.Agent, warning.Text)
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}
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return warnings
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}
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