Fix nginx --dry-run (#4889)

* Revert "Don't save keys/csr on dry run (#4380)"

This reverts commit e034b50363.

* Don't save CSRs and keys during dry run

* Factor out _test_obtain_certificate_common

* Add test_obtain_certificate_dry_run

* Wrap key from make_key in util.Key

* Wrap result from make_csr in util.CSR

certbot/client.py

@@ -9,6 +9,7 @@ import OpenSSL
 import zope.component
 
 from acme import client as acme_client
+from acme import crypto_util as acme_crypto_util
 from acme import errors as acme_errors
 from acme import jose
 from acme import messages
@@ -319,9 +320,17 @@ class Client(object):
         domains = [d for d in domains if d in auth_domains]
 
         # Create CSR from names
-        key = crypto_util.init_save_key(
-            self.config.rsa_key_size, self.config.key_dir)
-        csr = crypto_util.init_save_csr(key, domains, self.config.csr_dir)
+        if self.config.dry_run:
+            key = util.Key(file=None,
+                           pem=crypto_util.make_key(self.config.rsa_key_size))
+            csr = util.CSR(file=None, form="pem",
+                           data=acme_crypto_util.make_csr(
+                               key.pem, domains, self.config.must_staple))
+        else:
+            key = crypto_util.init_save_key(
+                self.config.rsa_key_size, self.config.key_dir)
+            csr = crypto_util.init_save_csr(key, domains, self.config.csr_dir)
+
         certr, chain = self.obtain_certificate_from_csr(
             domains, csr, authzr=authzr)