fix: 502 error on request to lms with large header

According to [1], request to uwsgi with header
larger than the default value 4096 will end up
with below error as #426:
  invalid request block size: 4123 (max 4096)...skip
  hr_instance_read(): Connection reset by peer
  [plugins/http/http.c line 647]

This commit fixes it by changing the maximum
buffer size as 4096

Also: Similar issue was already identifed and
fixed in [2] on tutor-ecommerce

[1] https://uwsgi-docs.readthedocs.io/en/latest/ThingsToKnow.html
[2] 6df2c99362

Close #426

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Note: Breaking changes between versions are indicated by "💥".
 
+## unreleased
+
+- [Bugfix] Fix 502 error on request to lms with header larger than the maximum uwsgi buffer size
+
 ## v11.2.8 (2021-04-27)
 
 - [Bugfix] Fix parsing of YAML-formatted values in ``config save --set KEY=VALUE`` commands, in use for instance with Ecommerce.

tutor/templates/build/openedx/Dockerfile

@@ -214,4 +214,5 @@ CMD uwsgi \
     --single-interpreter \
     --enable-threads \
     --processes=${UWSGI_WORKERS:-2} \
+    --buffer-size=8192 \
     --wsgi-file ${SERVICE_VARIANT}/wsgi.py