Recently, I've found myself unable to upload images to this blog, and for a while I thought it was some bug in my code as a result of updating some dependencies or something.

However, after some debugging it turned out that it was the way I have my infrastructure setup. The server that hosts www.jasonernst.com runs an nginx-proxy and this blog runs behind that. I also serve a few other websites from it as well (it also makes for an easy setup with letsenrypt).

When I tried to upload a file, I was getting a 413 Request Entity Too Large. At first I thought it was something related to gin-gonic, which this site is based on, and I increased the max size there to no effect. I then thought it might be some CORS related stuff, but nothing I tried there worked either (there have been some updates with how CORS and gin-gonic work together since I last took a look at this).

Finally, when I increased the javascript debugging, I noticed that the error was coming from nginx, and I realized what happened. Here's how I fixed it in my ansible setup:

- name: Create nginx directory on host
  tags: proxy
  become: true
  file:
    path: /etc/nginx/conf.d
    state: directory
    mode: '755'
    owner: root
    group: root

- name: Copy nginx config to host
  tags: proxy
  become: true
  copy:
    src: conf/proxy.conf
    dest: /etc/nginx/conf.d
    mode: '644'
    owner: root
    group: root

- name: pull and run the nginx reverse proxy
  tags: proxy
  vars:
    ansible_python_interpreter: "/usr/bin/env python3-docker"
  docker_container:
    name: nginx-proxy
    image: jwilder/nginx-proxy
    published_ports: 80:80,443:443
    volumes: /etc/nginx/conf.d:/etc/nginx/conf.d,vhost:/etc/nginx/vhost.d,html:/usr/share/nginx/html,dhparam:/etc/nginx/dhparam,certs:/etc/nginx/certs:ro,/var/run/docker.sock:/tmp/docker.sock:ro
    network_mode: bridge
    restart_policy: unless-stopped

(Created the directory on the host that is running the containers, added the config file defined in ansible, and then added a mapped volume from the config directory on the host into the container.

I then added a file in conf/proxy.conf at the same level as the task with these contents:

client_max_body_size 100m;