Update doc section Troubleshooting -> Login Error

New Firefox cookie import script, based on a comment in #615:
https://github.com/instaloader/instaloader/issues/615#issuecomment-630127064

docs/codesnippets/615_import_firefox_session.py

@@ -0,0 +1,53 @@
+from argparse import ArgumentParser
+from glob import glob
+from os.path import expanduser
+from platform import system
+from sqlite3 import OperationalError, connect
+
+try:
+    from instaloader import ConnectionException, Instaloader
+except ModuleNotFoundError:
+    raise SystemExit("Instaloader not found.\n  pip install [--user] instaloader")
+
+
+def get_cookiefile() -> str:
+    default_cookiefile = {
+        "Windows": "~/AppData/Roaming/Mozilla/Firefox/Profiles/*/cookies.sqlite",
+        "Darwin": "~/Library/Application Support/Firefox/Profiles/*.default/cookies.sqlite",
+    }.get(system(), "~/.mozilla/firefox/*.default/cookies.sqlite")
+    cookiefiles = glob(expanduser(default_cookiefile))
+    if not cookiefiles:
+        raise SystemExit("No Firefox cookies.sqlite file found. Use -c COOKIEFILE.")
+    return cookiefiles[0]
+
+
+def import_session(cookiefile, sessionfile):
+    print(f"Using cookies from {cookiefile}.")
+    conn = connect(cookiefile)
+    try:
+        cookie_data = conn.execute(
+            "SELECT name, value FROM moz_cookies WHERE baseDomain='instagram.com'"
+        )
+    except OperationalError:
+        cookie_data = conn.execute(
+            "SELECT name, value FROM moz_cookies WHERE host LIKE '%instagram.com'"
+        )
+    instaloader = Instaloader(max_connection_attempts=1)
+    instaloader.context._session.cookies.update(cookie_data)
+    username = instaloader.test_login()
+    if not username:
+        raise SystemExit("Not logged in. Are you logged in successfully in Firefox?")
+    print(f"Imported session cookie for {username}.")
+    instaloader.context.username = username
+    instaloader.save_session_to_file(sessionfile)
+
+
+if __name__ == "__main__":
+    p = ArgumentParser()
+    p.add_argument("-c", "--cookiefile")
+    p.add_argument("-f", "--sessionfile")
+    args = p.parse_args()
+    try:
+        import_session(args.cookiefile or get_cookiefile(), args.sessionfile)
+    except (ConnectionException, OperationalError) as e:
+        raise SystemExit(f"Cookie import failed: {e}")

docs/codesnippets/92_import_firefox_session.py

@@ -1,23 +0,0 @@
-from glob import glob
-from os.path import expanduser
-from sqlite3 import connect
-
-from instaloader import ConnectionException, Instaloader
-
-# FIREFOXCOOKIEFILE = "/home/alex/.mozilla/firefox/l96w6b90.default/cookies.sqlite"
-FIREFOXCOOKIEFILE = glob(expanduser("~/.mozilla/firefox/*.default/cookies.sqlite"))[0]
-
-instaloader = Instaloader(max_connection_attempts=1)
-instaloader.context._session.cookies.update(connect(FIREFOXCOOKIEFILE)
-                                            .execute("SELECT name, value FROM moz_cookies "
-                                                     "WHERE baseDomain='instagram.com'"))
-
-try:
-    username = instaloader.test_login()
-    if not username:
-        raise ConnectionException()
-except ConnectionException:
-    raise SystemExit("Cookie import failed. Are you logged in successfully in Firefox?")
-
-instaloader.context.username = username
-instaloader.save_session_to_file()

docs/conf.py

@@ -49,7 +49,22 @@ autodoc_member_order = 'bysource'
 intersphinx_mapping = {'python': ('https://docs.python.org/3', None),
                        'requests': ('https://requests.kennethreitz.org/en/master/', None)}
 
-extlinks = {'issue': ('https://github.com/instaloader/instaloader/issues/%s', 'issue #')}
+current_release = subprocess.check_output(["git", "describe", "--abbrev=0"]).decode("ascii")[1:-1]
+current_release_date = subprocess.check_output(
+    ["git", "log", "-1", "--tags", "--format=%ad", "--date=format:%e %b %Y"]).decode("ascii")[:-1]
+
+html_context = {'current_release': current_release, 'current_release_date': current_release_date}
+
+extlinks = {
+    'issue': (
+        'https://github.com/instaloader/instaloader/issues/%s',
+        'Issue #'
+    ),
+    'example': (
+        'https://raw.githubusercontent.com/instaloader/instaloader/v' + current_release + '/docs/codesnippets/%s',
+        'Example '
+    ),
+}
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
@@ -69,7 +84,7 @@ master_doc = 'index'
 
 # General information about the project.
 project = 'Instaloader'
-copyright = '2017, Alexander Graf and Andre Koch-Kramer'
+copyright = '2017-2020, Alexander Graf and Andre Koch-Kramer'
 author = 'Alexander Graf and Andre Koch-Kramer'
 
 # The version info for the project you're documenting, acts as replacement for
@@ -353,12 +368,6 @@ texinfo_documents = [
 # texinfo_no_detailmenu = False
 
 
-current_release = subprocess.check_output(["git", "describe", "--abbrev=0"]).decode("ascii")[1:-1]
-current_release_date = subprocess.check_output(["git", "log", "-1", "--tags", "--format=%ad", "--date=format:%e %b %Y"]).decode("ascii")[:-1]
-
-html_context = {'current_release': current_release, 'current_release_date': current_release_date}
-
-
 def setup(app):
     typing.TYPE_CHECKING = True
     app.add_stylesheet("instaloader.css")

docs/troubleshooting.rst

@@ -32,7 +32,7 @@ rate limit has almost been reached, according to Instaloader's own rate
 accounting mechanism. We regularly adjust this mechanism to match Instagram's
 current rate limiting.
 
-Login error
+Login Error
 -----------
 
 Instaloader's login *should* work fine, both with and without
@@ -40,21 +40,31 @@ Two-Factor-Authentication. It also supports handling the *checkpoint challenge*,
 issued when Instagram suspects authentication activity on your account, by
 pointing the user to an URL to be opened in a browser.
 
-Nevertheless, in :issue:`92` users report problems with logging in. To still use
+Nevertheless, in :issue:`92` and :issue:`615` users reported problems with
-Instaloader's logged-in functionality, you may use the following script to
+logging in. We recommend to always keep the sessionfile which Instaloader
-workaround login problems by importing the session cookies from Firefox and
+creates when using :option:`--login`. If a sessionfile is present,
-bypassing Instaloader's login.
+:option:`--login` does not make make use of the failure-prone login procedure.
+Also, sessionfiles usually do not expire and can be copied between different
+computers without any problems.
 
-.. literalinclude:: codesnippets/92_import_firefox_session.py
+If you do not have a sessionfile present, you may use the following script
+(:example:`615_import_firefox_session.py`) to workaround login problems by
+importing the session cookies from Firefox and bypassing Instaloader's login and
+so still use Instaloader's logged-in functionality.
 
-To use this,
+.. literalinclude:: codesnippets/615_import_firefox_session.py
 
-#. login to Instagram in Firefox, 
+To use this script,
 
-#. execute the snippet,
+#. Download the script: :example:`615_import_firefox_session.py`,
 
-#. then, ``instaloader -l USERNAME`` should work fine.
+#. Login to Instagram in Firefox,
 
-If you do not use your default firefox profile, or your operating system has the
+#. Execute the snippet, e.g. with ``python 615_import_firefox_session.py``,
-paths differently set up, you may have to alter the ``FIREFOXCOOKIEFILE``
+
-variable first.
+#. Then, ``instaloader -l USERNAME`` should work fine.
+
+This script also supports specifying a cookiefile path, which may be useful if
+you use multiple Firefox profiles or if your operating system has the directory
+structure differently set up. Also, you can specify an alternative sessionfile
+path.