Remove warning about logging in to ESGF (#2326)

doc/quickstart/configure.rst

@@ -382,8 +382,8 @@ corresponding command line arguments ``--search_esgf=when_missing`` or
  tool by pressing the ``Ctrl`` and ``C`` keys on your keyboard simultaneously
  several times, edit the recipe so it contains fewer datasets and try again.
 
-For downloading some files (e.g. those produced by the CORDEX project),
-you need to log in to be able to download the data.
+For downloading some files, you may need to log in to be able to download the
+data.
 
 See the
 `ESGF user guide <https://esgf.github.io/esgf-user-support/user_guide.html>`_

esmvalcore/config/_esgf_pyclient.py

@@ -12,7 +12,6 @@
 import logging
 import os
 import stat
-import textwrap
 from functools import lru_cache
 from pathlib import Path
 from types import ModuleType
@@ -30,59 +29,6 @@
 
 CONFIG_FILE = Path.home() / '.esmvaltool' / 'esgf-pyclient.yml'
 
-INSTRUCTIONS = textwrap.dedent("""
-ESGF credentials missing, only data that is accessible without
-logging in will be available.
-
-See https://esgf.github.io/esgf-user-support/user_guide.html
-for instructions on how to create an account if you do not have
-one yet.
-
-Next, configure your system so esmvaltool can use your
-credentials. This can be done using the keyring package, or
-you can just enter them in {cfg_file}.
-
-keyring
-=======
-First install the keyring package (requires a supported
-backend, see https://pypi.org/project/keyring/):
-$ pip install keyring
-
-Next, set your username and password by running the commands:
-$ keyring set ESGF hostname
-$ keyring set ESGF username
-$ keyring set ESGF password
-
-To check that you entered your credentials correctly, run:
-$ keyring get ESGF hostname
-$ keyring get ESGF username
-$ keyring get ESGF password
-
-configuration file
-==================
-You can store the hostname, username, and password or your OpenID
-account in a plain text in the file {cfg_file} like this:
-
-logon:
- hostname: "your-hostname"
- username: "your-username"
- password: "your-password"
-
-or your can configure an interactive log in:
-
-logon:
- interactive: true
-
-Note that storing your password in plain text in the configuration
-file is less secure. On shared systems, make sure the permissions
-of the file are set so only you can read it, i.e.
-
-$ ls -l {cfg_file}
-
-shows permissions -rw-------.
-
-""".format(cfg_file=CONFIG_FILE))
-
 
 def get_keyring_credentials():
  """Load credentials from keyring."""
@@ -172,14 +118,6 @@ def load_esgf_pyclient_config():
  cfg['search_connection']['cache'] = cache_file
  Path(cache_file).parent.mkdir(parents=True, exist_ok=True)
 
- missing_credentials = []
- for key in ['hostname', 'username', 'password']:
- if key not in cfg['logon']:
- missing_credentials.append(key)
-
- if missing_credentials and not cfg['logon'].get('interactive'):
- logger.warning(INSTRUCTIONS)
-
  return cfg