From e521333b750abbf39f90c6011d693e3f6b15bdd0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9gis=20Behmo?= <regis@behmo.com>
Date: Fri, 27 Mar 2020 09:59:11 +0100
Subject: [PATCH] Fix tls certificate generation in cron jobs

tls renewal and generation was failing in cron jobs because of "The
input device is not a TTY" errors. This is because the "-it" docker
option does not work when a tty is not available.
---
 CHANGELOG.md              |  4 ++++
 tutor/commands/compose.py |  6 +++++-
 tutor/utils.py            | 12 +++++++++++-
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f43c7eb..589b233 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 Note: Breaking changes between versions are indicated by "💥".
 
+## Unreleased
+
+- [Bugfix] Fix tls certificate generation in cron jobs
+
 ## v3.11.6 (2020-03-13)
 
 - [Bugfix] Fix "Unable to resolve dependency" error during forum initialisation
diff --git a/tutor/commands/compose.py b/tutor/commands/compose.py
index 5bb5bd5..e0f7b1e 100644
--- a/tutor/commands/compose.py
+++ b/tutor/commands/compose.py
@@ -3,6 +3,7 @@ import click
 from .. import config as tutor_config
 from .. import fmt
 from .. import scripts
+from .. import utils
 
 
 class ScriptRunner(scripts.BaseRunner):
@@ -90,7 +91,10 @@ def restart(context, services):
 @click.pass_obj
 def run(context, args):
     config = tutor_config.load(context.root)
-    context.docker_compose(context.root, config, "run", "--rm", *args)
+    command = ["run", "--rm"]
+    if not utils.is_a_tty():
+        command.append("-T")
+    context.docker_compose(context.root, config, *command, *args)
 
 
 @click.command(
diff --git a/tutor/utils.py b/tutor/utils.py
index 979a652..03f73f2 100644
--- a/tutor/utils.py
+++ b/tutor/utils.py
@@ -4,6 +4,7 @@ import random
 import shutil
 import string
 import subprocess
+import sys
 
 import click
 
@@ -66,7 +67,10 @@ def walk_files(path):
 
 
 def docker_run(*command):
-    return docker("run", "--rm", "-it", *command)
+    args = ["run", "--rm"]
+    if is_a_tty():
+        args.append("-it")
+    return docker(*args, *command)
 
 
 def docker(*command):
@@ -92,6 +96,12 @@ def kubectl(*command):
         )
     return execute("kubectl", *command)
 
+def is_a_tty():
+    """
+    Return True if stdin is able to allocate a tty. Tty allocation sometimes cannot be
+    enabled, for instance in cron jobs
+    """
+    return os.isatty(sys.stdin.fileno())
 
 def execute(*command):
     click.echo(fmt.command(" ".join(command)))