xcaddy/environment.go

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// Copyright 2020 Matthew Holt
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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package xcaddy
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import (
"bytes"
"context"
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"fmt"
"html/template"
"io/ioutil"
"log"
"os"
"os/exec"
"path/filepath"
"strings"
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"time"
)
func (b Builder) newEnvironment(ctx context.Context) (*environment, error) {
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// assume Caddy v2 if no semantic version is provided
caddyModulePath := defaultCaddyModulePath
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if !strings.HasPrefix(b.CaddyVersion, "v") || !strings.Contains(b.CaddyVersion, ".") {
caddyModulePath += "/v2"
}
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caddyModulePath, err := versionedModulePath(caddyModulePath, b.CaddyVersion)
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if err != nil {
return nil, err
}
// clean up any SIV-incompatible module paths real quick
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for i, p := range b.Plugins {
b.Plugins[i].ModulePath, err = versionedModulePath(p.ModulePath, p.Version)
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if err != nil {
return nil, err
}
}
// create the context for the main module template
tplCtx := goModTemplateContext{
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CaddyModule: caddyModulePath,
}
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for _, p := range b.Plugins {
tplCtx.Plugins = append(tplCtx.Plugins, p.ModulePath)
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}
// evaluate the template for the main module
var buf bytes.Buffer
tpl, err := template.New("main").Parse(mainModuleTemplate)
if err != nil {
return nil, err
}
err = tpl.Execute(&buf, tplCtx)
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if err != nil {
return nil, err
}
// create the folder in which the build environment will operate
tempFolder, err := newTempFolder()
if err != nil {
return nil, err
}
defer func() {
if err != nil {
err2 := os.RemoveAll(tempFolder)
if err2 != nil {
err = fmt.Errorf("%w; additionally, cleaning up folder: %v", err, err2)
}
}
}()
log.Printf("[INFO] Temporary folder: %s", tempFolder)
// write the main module file to temporary folder
mainPath := filepath.Join(tempFolder, "main.go")
log.Printf("[INFO] Writing main module: %s", mainPath)
err = ioutil.WriteFile(mainPath, buf.Bytes(), 0644)
if err != nil {
return nil, err
}
env := &environment{
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caddyVersion: b.CaddyVersion,
plugins: b.Plugins,
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caddyModulePath: caddyModulePath,
tempFolder: tempFolder,
timeoutGoGet: b.TimeoutGet,
skipCleanup: b.SkipCleanup,
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}
// initialize the go module
log.Println("[INFO] Initializing Go module")
cmd := env.newCommand("go", "mod", "init", "caddy")
err = env.runCommand(ctx, cmd, 10*time.Second)
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if err != nil {
return nil, err
}
// specify module replacements before pinning versions
replaced := make(map[string]string)
for _, r := range b.Replacements {
log.Printf("[INFO] Replace %s => %s", r.Old, r.New)
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cmd := env.newCommand("go", "mod", "edit",
"-replace", fmt.Sprintf("%s=%s", r.Old, r.New))
err := env.runCommand(ctx, cmd, 10*time.Second)
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if err != nil {
return nil, err
}
replaced[r.Old] = r.New
}
// check for early abort
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
}
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// pin versions by populating go.mod, first for Caddy itself and then plugins
log.Println("[INFO] Pinning versions")
err = env.execGoGet(ctx, caddyModulePath, env.caddyVersion)
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if err != nil {
return nil, err
}
nextPlugin:
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for _, p := range b.Plugins {
// if module is locally available, do not "go get" it;
// also note that we iterate and check prefixes, because
// a plugin package may be a subfolder of a module, i.e.
// foo/a/plugin is within module foo/a.
for repl := range replaced {
if strings.HasPrefix(p.ModulePath, repl) {
continue nextPlugin
}
}
err = env.execGoGet(ctx, p.ModulePath, p.Version)
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if err != nil {
return nil, err
}
// check for early abort
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
}
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}
log.Println("[INFO] Build environment ready")
return env, nil
}
type environment struct {
caddyVersion string
plugins []Dependency
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caddyModulePath string
tempFolder string
timeoutGoGet time.Duration
skipCleanup bool
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}
// Close cleans up the build environment, including deleting
// the temporary folder from the disk.
func (env environment) Close() error {
if env.skipCleanup {
log.Printf("[INFO] Skipping cleanup as requested; leaving folder intact: %s", env.tempFolder)
return nil
}
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log.Printf("[INFO] Cleaning up temporary folder: %s", env.tempFolder)
return os.RemoveAll(env.tempFolder)
}
func (env environment) newCommand(command string, args ...string) *exec.Cmd {
cmd := exec.Command(command, args...)
cmd.Dir = env.tempFolder
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
return cmd
}
func (env environment) runCommand(ctx context.Context, cmd *exec.Cmd, timeout time.Duration) error {
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log.Printf("[INFO] exec (timeout=%s): %+v ", timeout, cmd)
if timeout > 0 {
var cancel context.CancelFunc
ctx, cancel = context.WithTimeout(ctx, timeout)
defer cancel()
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}
// start the command; if it fails to start, report error immediately
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err := cmd.Start()
if err != nil {
return err
}
// wait for the command in a goroutine; the reason for this is
// very subtle: if, in our select, we do `case cmdErr := <-cmd.Wait()`,
// then that case would be chosen immediately, because cmd.Wait() is
// immediately available (even though it blocks for potentially a long
// time, it can be evaluated immediately). So we have to remove that
// evaluation from the `case` statement.
cmdErrChan := make(chan error)
go func() {
cmdErrChan <- cmd.Wait()
}()
// unblock either when the command finishes, or when the done
// channel is closed -- whichever comes first
select {
case cmdErr := <-cmdErrChan:
// process ended; report any error immediately
return cmdErr
case <-ctx.Done():
// context was canceled, either due to timeout or
// maybe a signal from higher up canceled the parent
// context; presumably, the OS also sent the signal
// to the child process, so wait for it to die
select {
case <-time.After(15 * time.Second):
cmd.Process.Kill()
case <-cmdErrChan:
}
return ctx.Err()
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}
}
func (env environment) execGoGet(ctx context.Context, modulePath, moduleVersion string) error {
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mod := modulePath
if moduleVersion != "" {
mod += "@" + moduleVersion
}
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cmd := env.newCommand("go", "get", "-d", "-v", mod)
return env.runCommand(ctx, cmd, env.timeoutGoGet)
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}
type goModTemplateContext struct {
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CaddyModule string
Plugins []string
}
const mainModuleTemplate = `package main
import (
caddycmd "{{.CaddyModule}}/cmd"
// plug in Caddy modules here
_ "{{.CaddyModule}}/modules/standard"
{{- range .Plugins}}
_ "{{.}}"
{{- end}}
)
func main() {
caddycmd.Main()
}
`