93 lines
2.2 KiB
Go
93 lines
2.2 KiB
Go
// Package main provides a utility program to launch the Dex container process with an optional
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// templating step (provided by gomplate).
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//
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// This was originally written as a shell script, but we rewrote it as a Go program so that it could
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// run as a raw binary in a distroless container.
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package main
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import (
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"fmt"
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"os"
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"os/exec"
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"strings"
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"syscall"
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)
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func main() {
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// Note that this docker-entrypoint program is args[0], and it is provided with the true process
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// args.
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args := os.Args[1:]
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if err := run(args, realExec, realWhich); err != nil {
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fmt.Println("error:", err.Error())
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os.Exit(1)
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}
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}
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func realExec(fork bool, args ...string) error {
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if fork {
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if output, err := exec.Command(args[0], args[1:]...).CombinedOutput(); err != nil {
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return fmt.Errorf("cannot fork/exec command %s: %w (output: %q)", args, err, string(output))
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}
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return nil
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}
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argv0, err := exec.LookPath(args[0])
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if err != nil {
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return fmt.Errorf("cannot lookup path for command %s: %w", args[0], err)
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}
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if err := syscall.Exec(argv0, args, os.Environ()); err != nil {
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return fmt.Errorf("cannot exec command %s (%q): %w", args, argv0, err)
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}
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return nil
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}
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func realWhich(path string) string {
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fullPath, err := exec.LookPath(path)
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if err != nil {
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return ""
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}
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return fullPath
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}
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func run(args []string, execFunc func(bool, ...string) error, whichFunc func(string) string) error {
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if args[0] != "dex" && args[0] != whichFunc("dex") {
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return execFunc(false, args...)
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}
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if args[1] != "serve" {
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return execFunc(false, args...)
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}
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newArgs := []string{}
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for _, tplCandidate := range args {
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if hasSuffixes(tplCandidate, ".tpl", ".tmpl", ".yaml") {
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tmpFile, err := os.CreateTemp("/tmp", "dex.config.yaml-*")
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if err != nil {
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return fmt.Errorf("cannot create temp file: %w", err)
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}
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if err := execFunc(true, "gomplate", "-f", tplCandidate, "-o", tmpFile.Name()); err != nil {
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return err
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}
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newArgs = append(newArgs, tmpFile.Name())
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} else {
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newArgs = append(newArgs, tplCandidate)
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}
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}
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return execFunc(false, newArgs...)
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}
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func hasSuffixes(s string, suffixes ...string) bool {
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for _, suffix := range suffixes {
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if strings.HasSuffix(s, suffix) {
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return true
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}
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}
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return false
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}
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