85 lines
2.4 KiB
Go
85 lines
2.4 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package logknob provides a helpful wrapper that allows enabling logging
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// based on either an envknob or other methods of enablement.
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package logknob
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import (
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"slices"
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"sync/atomic"
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"tailscale.com/envknob"
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"tailscale.com/types/logger"
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)
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// TODO(andrew-d): should we have a package-global registry of logknobs? It
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// would allow us to update from a netmap in a central location, which might be
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// reason enough to do it...
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// LogKnob allows configuring verbose logging, with multiple ways to enable. It
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// supports enabling logging via envknob, via atomic boolean (for use in e.g.
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// c2n log level changes), and via capabilities from a NetMap (so users can
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// enable logging via the ACL JSON).
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type LogKnob struct {
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capName string
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cap atomic.Bool
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env func() bool
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manual atomic.Bool
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}
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// NewLogKnob creates a new LogKnob, with the provided environment variable
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// name and/or NetMap capability.
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func NewLogKnob(env, cap string) *LogKnob {
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if env == "" && cap == "" {
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panic("must provide either an environment variable or capability")
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}
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lk := &LogKnob{
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capName: cap,
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}
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if env != "" {
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lk.env = envknob.RegisterBool(env)
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} else {
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lk.env = func() bool { return false }
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}
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return lk
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}
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// Set will cause logs to be printed when called with Set(true). When called
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// with Set(false), logs will not be printed due to an earlier call of
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// Set(true), but may be printed due to either the envknob and/or capability of
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// this LogKnob.
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func (lk *LogKnob) Set(v bool) {
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lk.manual.Store(v)
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}
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// NetMap is an interface for the parts of netmap.NetworkMap that we care
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// about; we use this rather than a concrete type to avoid a circular
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// dependency.
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type NetMap interface {
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SelfCapabilities() []string
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}
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// UpdateFromNetMap will enable logging if the SelfNode in the provided NetMap
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// contains the capability provided for this LogKnob.
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func (lk *LogKnob) UpdateFromNetMap(nm NetMap) {
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if lk.capName == "" {
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return
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}
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lk.cap.Store(slices.Contains(nm.SelfCapabilities(), lk.capName))
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}
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// Do will call log with the provided format and arguments if any of the
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// configured methods for enabling logging are true.
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func (lk *LogKnob) Do(log logger.Logf, format string, args ...any) {
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if lk.shouldLog() {
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log(format, args...)
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}
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}
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func (lk *LogKnob) shouldLog() bool {
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return lk.manual.Load() || lk.env() || lk.cap.Load()
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}
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