mirror of
https://github.com/caddyserver/caddy.git
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118 lines
3.1 KiB
Go
118 lines
3.1 KiB
Go
// Copyright 2015 Matthew Holt and The Caddy Authors
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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 caddy
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import (
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"os"
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"path/filepath"
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"runtime"
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"strings"
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)
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// Replacer can replace values in strings.
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type Replacer interface {
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Set(variable, value string)
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Delete(variable string)
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Map(func() map[string]string)
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ReplaceAll(input, empty string) string
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}
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// NewReplacer returns a new Replacer.
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func NewReplacer() Replacer {
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rep := &replacer{
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static: make(map[string]string),
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}
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rep.providers = []ReplacementsFunc{
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defaultReplacements,
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func() map[string]string { return rep.static },
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}
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return rep
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}
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type replacer struct {
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providers []ReplacementsFunc
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static map[string]string
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}
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// Map augments the map of replacements with those returned
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// by the given replacements function. The function is only
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// executed at replace-time.
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func (r *replacer) Map(replacements func() map[string]string) {
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r.providers = append(r.providers, replacements)
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}
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// Set sets a custom variable to a static value.
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func (r *replacer) Set(variable, value string) {
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r.static[variable] = value
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}
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// Delete removes a variable with a static value
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// that was created using Set.
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func (r *replacer) Delete(variable string) {
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delete(r.static, variable)
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}
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// ReplaceAll replaces placeholders in input with their values.
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// Values that are empty string will be substituted with the
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// empty parameter.
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func (r *replacer) ReplaceAll(input, empty string) string {
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if !strings.Contains(input, phOpen) {
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return input
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}
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for _, replacements := range r.providers {
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for key, val := range replacements() {
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if val == "" {
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val = empty
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}
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input = strings.ReplaceAll(input, phOpen+key+phClose, val)
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}
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}
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return input
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}
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// ReplacementsFunc is a function that returns replacements,
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// which is variable names mapped to their values. The
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// function will be evaluated only at replace-time to ensure
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// the most current values are mapped.
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type ReplacementsFunc func() map[string]string
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var defaultReplacements = func() map[string]string {
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m := map[string]string{
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"system.hostname": func() string {
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// OK if there is an error; just return empty string
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name, _ := os.Hostname()
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return name
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}(),
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"system.slash": string(filepath.Separator),
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"system.os": runtime.GOOS,
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"system.arch": runtime.GOARCH,
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}
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// add environment variables
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for _, keyval := range os.Environ() {
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parts := strings.SplitN(keyval, "=", 2)
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if len(parts) != 2 {
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continue
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}
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m["env."+strings.ToUpper(parts[0])] = parts[1]
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}
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return m
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}
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// ReplacerCtxKey is the context key for a replacer.
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const ReplacerCtxKey CtxKey = "replacer"
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const phOpen, phClose = "{", "}"
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