139 lines
3.9 KiB
Go
139 lines
3.9 KiB
Go
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// Copyright 2021 by the contributors.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package internalserver
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import (
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"fmt"
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"net/http"
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"net/http/pprof"
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"sort"
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"github.com/metalmatze/signal/healthcheck"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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// Handler is a http.ServeMux that knows about all endpoints to render a nice index page.
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type Handler struct {
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http.ServeMux
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endpoints []endpoint
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name string
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}
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// endpoint has a description to a pattern.
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type endpoint struct {
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Pattern string
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Description string
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}
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// NewHandler creates a new internalserver Handler.
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func NewHandler(options ...Option) *Handler {
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h := &Handler{name: "Internal"}
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for _, option := range options {
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option(h)
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}
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h.HandleFunc("/", h.index)
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return h
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}
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// AddEndpoint wraps HandleFunc for adding http handlers to add a meaningful description to the index page.
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func (h *Handler) AddEndpoint(pattern string, description string, handler http.HandlerFunc) {
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h.endpoints = append(h.endpoints, endpoint{
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Pattern: pattern,
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Description: description,
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})
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// Sort endpoints by pattern after adding a new one, to always show them in the same order.
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sort.Slice(h.endpoints, func(i, j int) bool {
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return h.endpoints[i].Pattern < h.endpoints[j].Pattern
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})
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h.HandleFunc(pattern, handler)
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}
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func (h *Handler) index(w http.ResponseWriter, r *http.Request) {
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html := fmt.Sprintf("<html><head><title>%s</title></head><body>\n", h.name)
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html += fmt.Sprintf("<h1>%s</h1>\n", h.name)
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for _, e := range h.endpoints {
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html += fmt.Sprintf("<p><a href='%s'>%s - %s</a></p>\n", e.Pattern, e.Pattern, e.Description)
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}
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html += `</body></html>`
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w.Header().Set("Content-Type", "text/html; charset=utf-8")
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_, _ = w.Write([]byte(html))
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}
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// Option is a func that modifies the configuration for the internalserver handler.
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type Option func(h *Handler)
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// WithName allows to set an application name for the internalserver handler.
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func WithName(name string) Option {
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return func(h *Handler) {
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h.name = name
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}
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}
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// WithHealthchecks adds the healthchecks endpoints /live and /ready to the internalserver.
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func WithHealthchecks(healthchecks healthcheck.Handler) Option {
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return func(h *Handler) {
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h.AddEndpoint(
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"/live",
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"Exposes liveness checks",
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healthchecks.LiveEndpoint,
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)
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h.AddEndpoint(
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"/ready",
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"Exposes readiness checks",
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healthchecks.ReadyEndpoint,
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)
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}
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}
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// WithPrometheusRegistry adds a /metrics endpoint to the internalserver.
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func WithPrometheusRegistry(registry *prometheus.Registry) Option {
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return func(h *Handler) {
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h.AddEndpoint(
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"/metrics",
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"Exposes Prometheus metrics",
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promhttp.HandlerFor(registry, promhttp.HandlerOpts{}).ServeHTTP,
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)
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}
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}
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// WithPProf adds all pprof endpoints under /debug to the internalserver.
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func WithPProf() Option {
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return func(h *Handler) {
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m := http.NewServeMux()
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m.HandleFunc("/debug/pprof/", pprof.Index)
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m.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
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m.HandleFunc("/debug/pprof/profile", pprof.Profile)
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m.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
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m.HandleFunc("/debug/pprof/trace", pprof.Trace)
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m.HandleFunc("/debug/", func(w http.ResponseWriter, r *http.Request) {
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http.Redirect(w, r, "/debug/pprof/", http.StatusMovedPermanently)
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})
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h.AddEndpoint(
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"/debug/",
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"Exposes pprof endpoints to consume via HTTP",
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m.ServeHTTP,
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)
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}
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}
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