token-server: Warmup some local caches in /_ah/warmup.

tokenserver/appengine/impl/certchecker/warmup.go

Index: tokenserver/appengine/impl/certchecker/warmup.go
diff --git a/tokenserver/appengine/impl/certchecker/warmup.go b/tokenserver/appengine/impl/certchecker/warmup.go
index 8307d0aaac1f54b3999501e45d7eaec2d50e7f3c..c31a1824f54e30333eda53c56c78a973d1f6ffea 100644
--- a/tokenserver/appengine/impl/certchecker/warmup.go
+++ b/tokenserver/appengine/impl/certchecker/warmup.go
@@ -7,12 +7,27 @@ package certchecker
 import (
 	"golang.org/x/net/context"
 
+	"github.com/luci/luci-go/common/logging"
 	"github.com/luci/luci-go/server/warmup"
+	"github.com/luci/luci-go/tokenserver/appengine/impl/certconfig"
 )
 
 func init() {
 	warmup.Register("tokenserver/appengine/impl/certchecker", func(c context.Context) error {
-		// TODO
+		names, err := certconfig.ListCAs(c)
+		if err != nil {
+			return err
+		}
+		for _, cn := range names {
+			logging.Infof(c, "Warming up %q", cn)
+			checker, err := GetCertChecker(c, cn)
+			if err == nil {
+				_, err = checker.GetCA(c)
+			}
+			if err != nil {
+				logging.WithError(err).Warningf(c, "Failed to warm up %q", cn)

[nodir, 2017/03/29 21:45:06]

why it doesn't return err in this case but returns it @L19?

[Vadim Sh., 2017/03/29 21:49:30]

Because we don't want to do "return err" here, before checking all CAs, and I
didn't want to bother with MultiErrror handling :) Errors in warmup are not
really important.

[Vadim Sh., 2017/03/29 23:46:00]

Added MultiError.

+			}
+		}
 		return nil
 	})
 }