916ec63af6
This is a new revision of the discovery server. Relevant changes and non-changes: - Protocol towards clients is unchanged. - Recommended large scale design is still to be deployed nehind nginx (I tested, and it's still a lot faster at terminating TLS). - Database backend is leveldb again, only. It scales enough, is easy to setup, and we don't need any backend to take care of. - Server supports replication. This is a simple TCP channel - protect it with a firewall when deploying over the internet. (We deploy this within the same datacenter, and with firewall.) Any incoming client announces are sent over the replication channel(s) to other peer discosrvs. Incoming replication changes are applied to the database as if they came from clients, but without the TLS/certificate overhead. - Metrics are exposed using the prometheus library, when enabled. - The database values and replication protocol is protobuf, because JSON was quite CPU intensive when I tried that and benchmarked it. - The "Retry-After" value for failed lookups gets slowly increased from a default of 120 seconds, by 5 seconds for each failed lookup, independently by each discosrv. This lowers the query load over time for clients that are never seen. The Retry-After maxes out at 3600 after a couple of weeks of this increase. The number of failed lookups is stored in the database, now and then (avoiding making each lookup a database put). All in all this means clients can be pointed towards a cluster using just multiple A / AAAA records to gain both load sharing and redundancy (if one is down, clients will talk to the remaining ones). GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4648
65 lines
2.2 KiB
Go
65 lines
2.2 KiB
Go
package logrus
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// The following code was sourced and modified from the
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// https://github.com/tebeka/atexit package governed by the following license:
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//
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// Copyright (c) 2012 Miki Tebeka <miki.tebeka@gmail.com>.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy of
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// this software and associated documentation files (the "Software"), to deal in
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// the Software without restriction, including without limitation the rights to
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// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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// the Software, and to permit persons to whom the Software is furnished to do so,
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// subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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import (
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"fmt"
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"os"
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)
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var handlers = []func(){}
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func runHandler(handler func()) {
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defer func() {
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if err := recover(); err != nil {
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fmt.Fprintln(os.Stderr, "Error: Logrus exit handler error:", err)
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}
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}()
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handler()
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}
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func runHandlers() {
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for _, handler := range handlers {
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runHandler(handler)
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}
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}
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// Exit runs all the Logrus atexit handlers and then terminates the program using os.Exit(code)
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func Exit(code int) {
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runHandlers()
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os.Exit(code)
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}
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// RegisterExitHandler adds a Logrus Exit handler, call logrus.Exit to invoke
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// all handlers. The handlers will also be invoked when any Fatal log entry is
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// made.
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//
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// This method is useful when a caller wishes to use logrus to log a fatal
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// message but also needs to gracefully shutdown. An example usecase could be
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// closing database connections, or sending a alert that the application is
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// closing.
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func RegisterExitHandler(handler func()) {
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handlers = append(handlers, handler)
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}
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