aws elastic beanstalk "Request-URI Too Long" - apache

Question

I have a setup running a python flask app on elastic beanstalk. My Issue is that I'm getting this 414 error code. I have added LimitRequestLine 200000 to httpd.conf, and restarting with sudo httpd service restart on the shell of the ec2 instance, but it seems to not do the trick..
This works perfectly for an apache server running on ec2 not on elastic beanstalk. Maybe the load balancer is to blame?
I'd really appreciate any help on this...
another weird thing - if I restart httpd service from the shell on the ec2 instance, the long uri can pass once, and only once - second time I get the 414 again..
Thanks

Answer 1

A different way can be to directly modify the loadbalancer to increase the parameter "large_client_header_buffers". This might require an application load-balancer (compared to the default classic load-balancer).
E.g. create file files.config in the folder .ebextensions
files:
"/etc/nginx/conf.d/proxy.conf":
mode: "000755"
owner: root
group: root
content: |
large_client_header_buffers 16 1M;

Answer 2

LimitRequestLine should reside within <VirtualHost> section. Its quite tricky to do it in Elastic Beanstalk since you need to add this line to /etc/httpd/conf.d/wsgi.conf which is autogenerated after both commands and container_commands are run. Following idea from this blog, adding the following to config file under .ebextensions worked:
commands:
create_post_dir:
command: "mkdir -p /opt/elasticbeanstalk/hooks/appdeploy/post"
ignoreErrors: true
files:
"/opt/elasticbeanstalk/hooks/appdeploy/post/99_adjust_request_limit.sh":
mode: "000755"
owner: root
group: root
content: |
#!/usr/bin/env bash
sed -i.back '/<VirtualHost/aLimitRequestLine 100000' /etc/httpd/conf.d/wsgi.conf
supervisorctl -c /opt/python/etc/supervisord.conf restart httpd

Answer 3

None of the answers worked for me since I use the docker platform in EB, or maybe because things have changed lately. I solved it by grabbing the default nginx.conf from /etc/nginx/nginx.conf (in a running EB instance), then adding "large_client_header_buffers 16 1M;" in the proxy_pass directive that points to the docker app.
Then placing the nginx.conf file under .platform/nginx (since .ebextensions will be ignored for nginx config).
Your config file may differ so I suggest using that, but this is my working file:
# Elastic Beanstalk Nginx Configuration File
# For docker platform. Copied from /etc/nginx/nginx.conf
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;
worker_rlimit_nofile 67114;
events {
worker_connections 1024;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
access_log /var/log/nginx/access.log;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
include conf.d/*.conf;
map $http_upgrade $connection_upgrade {
default "upgrade";
}
server {
listen 80 default_server;
gzip on;
gzip_comp_level 4;
gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;
# Custom config to avoid http error 414 on large POST requests
large_client_header_buffers 16 1M;
access_log /var/log/nginx/access.log main;
location / {
proxy_pass http://docker;
proxy_http_version 1.1;
proxy_set_header Connection $connection_upgrade;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
# Include the Elastic Beanstalk generated locations
include conf.d/elasticbeanstalk/*.conf;
}
}