add support for resolving links locally

Specify a command line argument to resolve a link locally and exit. Also add a new flag, -resolve-from-backup, which loads a snapshot into an in-memory database and resolves the specified link.
contextco · Dec 6, 2022 · af7ceb5 · af7ceb5
1 parent 9d1e45f
commit af7ceb5
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Showing 3 changed files with 103 additions and 5 deletions.
diff --git a/README.md b/README.md
@@ -120,3 +120,7 @@ Only links that don't already exist in the database will be added.
  golink -snapshot links.json
 
 [JSON lines]: https://jsonlines.org/
+
+You can also resolve links locally using a snapshot file:
+
+ golink -resolve-from-backup links.json go/link
diff --git a/golink.go b/golink.go
@@ -36,11 +36,12 @@ import (
 const defaultHostname = "go"
 
 var (
- verbose = flag.Bool("verbose", false, "be verbose")
- sqlitefile = flag.String("sqlitedb", "", "path of SQLite database to store links")
- dev = flag.String("dev-listen", "", "if non-empty, listen on this addr and run in dev mode; auto-set sqlitedb if empty and don't use tsnet")
- snapshot = flag.String("snapshot", "", "file path of snapshot file")
- hostname = flag.String("hostname", defaultHostname, "service name")
+ verbose = flag.Bool("verbose", false, "be verbose")
+ sqlitefile = flag.String("sqlitedb", "", "path of SQLite database to store links")
+ dev = flag.String("dev-listen", "", "if non-empty, listen on this addr and run in dev mode; auto-set sqlitedb if empty and don't use tsnet")
+ snapshot = flag.String("snapshot", "", "file path of snapshot file")
+ hostname = flag.String("hostname", defaultHostname, "service name")
+ resolveFromBackup = flag.String("resolve-from-backup", "", "resolve a link from snapshot file and exit")
 )
 
 var stats struct {
@@ -66,6 +67,16 @@ var localClient *tailscale.LocalClient
 func Run() error {
  flag.Parse()
 
+ // if resolving from backup, set sqlitefile and snapshot flags to
+ // restore links into an in-memory sqlite database.
+ if *resolveFromBackup != "" {
+ *sqlitefile = ":memory:"
+ snapshot = resolveFromBackup
+ if flag.NArg() != 1 {
+ log.Fatal("--resolve-from-backup also requires a link to be resolved")
+ }
+ }
+
  if *sqlitefile == "" {
  if devMode() {
  tmpdir, err := ioutil.TempDir("", "golink_dev_*")
@@ -102,6 +113,16 @@ func Run() error {
  log.Printf("initializing stats: %v", err)
  }
 
+ // if link specified on command line, resolve and exit
+ if flag.NArg() > 0 {
+ destination, err := resolveLink(flag.Arg(0))
+ if err != nil {
+ log.Fatal(err)
+ }
+ fmt.Println(destination)
+ os.Exit(0)
+ }
+
  // flush stats periodically
  go flushStatsLoop()
 
@@ -588,3 +609,19 @@ func restoreLastSnapshot() error {
  }
  return bs.Err()
 }
+
+func resolveLink(link string) (string, error) {
+ // if link specified as "go/name", trim "go" prefix.
+ // Remainder will parse as URL with no scheme or host
+ link = strings.TrimPrefix(link, *hostname)
+ u, err := url.Parse(link)
+ if err != nil {
+ return "", err
+ }
+ short, remainder, _ := strings.Cut(strings.TrimPrefix(u.RequestURI(), "/"), "/")
+ l, err := db.Load(short)
+ if err != nil {
+ return "", err
+ }
+ return expandLink(l.Long, expandEnv{Now: time.Now().UTC(), Path: remainder})
+}
diff --git a/golink_test.go b/golink_test.go
@@ -87,3 +87,60 @@ func TestExpandLink(t *testing.T) {
  })
  }
 }
+
+func TestResolveLink(t *testing.T) {
+ var err error
+ db, err = NewSQLiteDB(":memory:")
+ if err != nil {
+ t.Fatal(err)
+ }
+ db.Save(&Link{Short: "meet", Long: "https://meet.google.com/lookup/"})
+ db.Save(&Link{Short: "cs", Long: "http://codesearch/{{with .Path}}search?q={{.}}{{end}}"})
+
+ tests := []struct {
+ link string
+ want string
+ }{
+ {
+ link: "meet",
+ want: "https://meet.google.com/lookup/",
+ },
+ {
+ link: "meet/foo",
+ want: "https://meet.google.com/lookup/foo",
+ },
+ {
+ link: "go/meet/foo",
+ want: "https://meet.google.com/lookup/foo",
+ },
+ {
+ link: "http://go/meet/foo",
+ want: "https://meet.google.com/lookup/foo",
+ },
+ {
+ // if absolute URL provided, host doesn't actually matter
+ link: "http://mygo/meet/foo",
+ want: "https://meet.google.com/lookup/foo",
+ },
+ {
+ link: "cs",
+ want: "http://codesearch/",
+ },
+ {
+ link: "cs/term",
+ want: "http://codesearch/search?q=term",
+ },
+ }
+ for _, tt := range tests {
+ name := "golink " + tt.link
+ t.Run(name, func(t *testing.T) {
+ got, err := resolveLink(tt.link)
+ if err != nil {
+ t.Error(err)
+ }
+ if got != tt.want {
+ t.Errorf("ResolveLink(%q) = %q; want %q", tt.link, got, tt.want)
+ }
+ })
+ }
+}