Modify http2_max_header_size for ddev-router

[mglaman]

Is there a way to increase http2_max_header_size for the ddev-router? We have instances where it needed to be bumped to 32k.

It looks like the only way is to create a new .ddev/router-compose.*.yml which adds a custom .conf in a volume mount to /etc/nginx/conf.d/.

I'm fine with it being a global change, but I was wondering if there was an easier way

[rfay]

Yes, ironically somebody has been working on this in recent days. You're exactly right about the technique.

It has to be global... if it's for the router.

[rfay]

BTW, we should probably just bump it, since two people have wanted that in recent days.

The other technique is to do a PR, we push the image with the changed value, and you add the image into your ~/.ddev/router-compose.newimage.yaml

[TravisWhitehead]

I think doubling http2_max_header_size in the router by default is reasonable. I'll open a PR.

In case this helps anyone-- I wanted to put my nginx config workaround for router in my project-level config (so devs working on a project would have the workaround applied w/o manual intervention), so I used pre-start hooks on the project-level to copy router-compose.override.yaml and related config files to the global ddev config dir. (Though some folks might prefer opting-in to something that touches their dotfiles instead of this happening automatically-- just a thought.)

Additional discussion on this topic found in Drupal Slack's #ddev channel: https://drupal.slack.com/archives/C5TQRQZRR/p1607733440364600

[rfay]

Related PR #2698

@TravisWhitehead if you got your workaround to work could you explain it and put it here?

[TravisWhitehead]

So I'm starting to doubt 32k as a solution (at least for our team's issue) because we're still exceeding the limit (just less frequently after increasing it). Apparently someone hit it even after increasing to 64k-- which makes me think there is an issue with our app accumulating cookies...

However it might still be a reasonable default for others.

My new workaround is to just disable HTTP/2 until I'll have time to dig into this more. A hack to disable HTTP/2 without having to mount over /etc/nginx/conf.d/ddev.conf (and without us having to maintain a downstream copy of nginx.tmpl):

# Disable HTTP/2 for Nginx in ddev-router
- exec-host: docker exec ddev-router sed -i 's/ http2//' /etc/nginx/conf.d/ddev.conf /tmp/https_ports.conf
- exec-host: docker exec ddev-router nginx -s reload

It's a fragile solution, it would probably be nicer to have the option of disabling HTTP/2 as a proper ddev configuration that propagates to nginx.tmpl.

[TravisWhitehead]

@TravisWhitehead if you got your workaround to work could you explain it and put it here?

Meanwhile, my previous workaround was to use router-compose.override.yaml to add Nginx config increasing the limits:

diff --git a/.ddev/config.yaml b/.ddev/config.yaml
index d1e3db99..cdc326a3 100644
--- a/.ddev/config.yaml
+++ b/.ddev/config.yaml
@@ -14,6 +14,10 @@ mariadb_version: ""
 mysql_version: "5.7"
 provider: default
 hooks:
+  pre-start:
+  # ddev-router config patching only works in global ddev config, so we copy files there
+  - exec-host: cp .ddev/nginx_http2_max_header_size.conf ~/.ddev/
+  - exec-host: cp .ddev/router-compose.nginx_http2_max_header_size_conf.yaml ~/.ddev/
   post-import-db:
   - exec: drush updb -y
   - exec: drush en stage_file_proxy devel module_filter permissions_helper -y
diff --git a/.ddev/nginx_http2_max_header_size.conf b/.ddev/nginx_http2_max_header_size.conf
new file mode 100644
index 00000000..a3943086
--- /dev/null
+++ b/.ddev/nginx_http2_max_header_size.conf
@@ -0,0 +1,4 @@
+# This file only works in global ddev config, so the pre-composer hook copies to there.
+# Double limits for when our cookies get too big
+http2_max_header_size 32k;
diff --git a/.ddev/router-compose.nginx_http2_max_header_size_conf.yaml b/.ddev/router-compose.nginx_http2_max_header_size_conf.yaml
new file mode 100644
index 00000000..ce3ddd74
--- /dev/null
+++ b/.ddev/router-compose.nginx_http2_max_header_size_conf.yaml
@@ -0,0 +1,7 @@
+# Add custom nginx config to ddev-router
+# This file only works in global ddev config, so the pre-composer hook copies to there.
+ version: '3.6'
+ services:
+   ddev-router:
+     volumes:
+     - ./nginx_http2_max_header_size.conf:/etc/nginx/conf.d/00_nginx_http2_max_header_size.conf

[rfay]

#2698 went in for this to double the http2_max_header_size and will be in v1.17 alphas and then v1.17, but people may need the technique above someday in the future as well.