tailscale/cmd/tsconnect/common.go
Mihai Parparita b763a12331 cmd/tsconnect: allow building static resources in a different directory
When using tsconnect as a module in another repo, we cannot write to
the ./dist directory (modules directories are read-only by default -
there is a -modcacherw flag for `go get` but we can't count on it).

We add a -distdir flag that is honored by both the build and serve
commands for where to place output in.

Somewhat tedious because esbuild outputs paths relative to the working
directory, so we need to do some extra munging to make them relative
to the output directory.

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
2022-07-20 10:14:43 -07:00

115 lines
3.4 KiB
Go

// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"log"
"os"
"os/exec"
"path"
"path/filepath"
"runtime"
"strconv"
esbuild "github.com/evanw/esbuild/pkg/api"
)
const (
devMode = true
prodMode = false
)
// commonSetup performs setup that is common to both dev and build modes.
func commonSetup(dev bool) (*esbuild.BuildOptions, error) {
// Change cwd to to where this file lives -- that's where all inputs for
// esbuild and other build steps live.
if _, filename, _, ok := runtime.Caller(0); ok {
if err := os.Chdir(path.Dir(filename)); err != nil {
return nil, fmt.Errorf("Cannot change cwd: %w", err)
}
}
if err := buildDeps(dev); err != nil {
return nil, fmt.Errorf("Cannot build deps: %w", err)
}
return &esbuild.BuildOptions{
EntryPoints: []string{"src/index.js", "src/index.css"},
Loader: map[string]esbuild.Loader{".wasm": esbuild.LoaderFile},
Outdir: *distDir,
Bundle: true,
Sourcemap: esbuild.SourceMapLinked,
LogLevel: esbuild.LogLevelInfo,
Define: map[string]string{"DEBUG": strconv.FormatBool(dev)},
Target: esbuild.ES2017,
}, nil
}
// buildDeps builds the static assets that are needed for the server (except for
// JS/CSS bundling, which is handled by esbuild).
func buildDeps(dev bool) error {
if err := copyWasmExec(); err != nil {
return fmt.Errorf("Cannot copy wasm_exec.js: %w", err)
}
if err := buildWasm(dev); err != nil {
return fmt.Errorf("Cannot build main.wasm: %w", err)
}
if err := installJSDeps(); err != nil {
return fmt.Errorf("Cannot install JS deps: %w", err)
}
return nil
}
// copyWasmExec grabs the current wasm_exec.js runtime helper library from the
// Go toolchain.
func copyWasmExec() error {
log.Printf("Copying wasm_exec.js...\n")
wasmExecSrcPath := filepath.Join(runtime.GOROOT(), "misc", "wasm", "wasm_exec.js")
wasmExecDstPath := filepath.Join("src", "wasm_exec.js")
contents, err := os.ReadFile(wasmExecSrcPath)
if err != nil {
return err
}
return os.WriteFile(wasmExecDstPath, contents, 0600)
}
// buildWasm builds the Tailscale wasm binary and places it where the JS can
// load it.
func buildWasm(dev bool) error {
log.Printf("Building wasm...\n")
args := []string{"build", "-tags", "tailscale_go,osusergo,netgo,nethttpomithttp2,omitidna,omitpemdecrypt"}
if !dev {
// Omit long paths and debug symbols in release builds, to reduce the
// generated WASM binary size.
args = append(args, "-trimpath", "-ldflags", "-s -w")
}
args = append(args, "-o", "src/main.wasm", "./wasm")
cmd := exec.Command(filepath.Join(runtime.GOROOT(), "bin", "go"), args...)
cmd.Env = append(os.Environ(), "GOOS=js", "GOARCH=wasm")
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
return cmd.Run()
}
// installJSDeps installs the JavaScript dependencies specified by package.json
func installJSDeps() error {
log.Printf("Installing JS deps...\n")
stdoutStderr, err := exec.Command("yarn").CombinedOutput()
if err != nil {
log.Printf("yarn failed: %s", stdoutStderr)
}
return err
}
// EsbuildMetadata is the subset of metadata struct (described by
// https://esbuild.github.io/api/#metafile) that we care about for mapping
// from entry points to hashed file names.
type EsbuildMetadata struct {
Outputs map[string]struct {
EntryPoint string `json:"entryPoint,omitempty"`
} `json:"outputs,omitempty"`
}