LimitRequestFieldSize does not work - configuration

I'm tryingo to set LimitRequestFieldSize on apache 2.2 configuration, but it does not work.
I can set header which has 16kb of size, LimitRequestFieldSize is set to 150 and everything works, so how can I limit size of Http request header?
I'm running Debian 7

Related

ERR_HTTP2_PROTOCOL_ERROR in Chrome. Works in Firefox [duplicate]

I'm currently working on a website, which triggers a net::ERR_HTTP2_PROTOCOL_ERROR 200 error on Google Chrome. I'm not sure exactly what can provoke this error, I just noticed it pops out only when accessing the website in HTTPS. I can't be 100% sure it is related, but it looks like it prevents JavaScript to be executed properly.
For instance, the following scenario happens :
I'm accessing the website in HTTPS
My Twitter feed integrated via https://publish.twitter.com isn't loaded at all
I can notice in the console the ERR_HTTP2_PROTOCOL_ERROR
If I remove the code to load the Twitter feed, the error remains
If I access the website in HTTP, the Twitter feed appears and the error disappears
Google Chrome is the only web browser triggering the error: it works well on both Edge and Firefox.
(NB: I tried with Safari, and I have a similar kcferrordomaincfnetwork 303 error)
I was wondering if it could be related to the header returned by the server since there is this '200' mention in the error, and a 404 / 500 page isn't triggering anything.
Thing is the error isn't documented at all. Google search gives me very few results. Moreover, I noticed it appears on very recent Google Chrome releases; the error doesn't pop on v.64.X, but it does on v.75+ (regardless of the OS; I'm working on Mac tho).
Might be related to Website OK on Firefox but not on Safari (kCFErrorDomainCFNetwork error 303) neither Chrome (net::ERR_SPDY_PROTOCOL_ERROR)
Findings from further investigations are the following:
error doesn't pop on the exact same page if server returns 404 instead of 2XX
error doesn't pop on local with a HTTPS certificate
error pops on a different server (both are OVH's), which uses a different certificate
error pops no matter what PHP version is used, from 5.6 to 7.3 (framework used : Cakephp 2.10)
As requested, below is the returned header for the failing ressource, which is the whole web page. Even if the error is triggering on each page having a HTTP header 200, those pages are always loading on client's browser, but sometimes an element is missing (in my exemple, the external Twitter feed). Every other asset on the Network tab has a success return, except the whole document itself.
Google Chrome header (with error):
Firefox header (without error):
A curl --head --http2 request in console returns the following success:
HTTP/2 200
date: Fri, 04 Oct 2019 08:04:51 GMT
content-type: text/html; charset=UTF-8
content-length: 127089
set-cookie: SERVERID31396=2341116; path=/; max-age=900
server: Apache
x-powered-by: PHP/7.2
set-cookie: xxxxx=0919c5563fc87d601ab99e2f85d4217d; expires=Fri, 04-Oct-2019 12:04:51 GMT; Max-Age=14400; path=/; secure; HttpOnly
vary: Accept-Encoding
Trying to go deeper with the chrome://net-export/ and https://netlog-viewer.appspot.com tools is telling me the request ends with a RST_STREAM :
t=123354 [st=5170] HTTP2_SESSION_RECV_RST_STREAM
--> error_code = "2 (INTERNAL_ERROR)"
--> stream_id = 1
For what I read in this other post, "In HTTP/2, if the client wants to abort the request, it sends a RST_STREAM. When the server receives a RST_STREAM, it will stop sending DATA frames to the client, thereby stopping the response (or the download). The connection is still usable for other requests, and requests/responses that were concurrent with the one that has been aborted may continue to progress.
[...]
It is possible that by the time the RST_STREAM travels from the client to the server, the whole content of the request is in transit and will arrive to the client, which will discard it. However, for large response contents, sending a RST_STREAM may have a good chance to arrive to the server before the whole response content is sent, and therefore will save bandwidth."
The described behavior is the same as the one I can observe. But that would mean the browser is the culprit, and then I wouldn't understand why it happens on two identical pages with one having a 200 header and the other a 404 (same goes if I disable JS).
In my case it was - no disk space left on the web server.
For several weeks I was also annoyed by this "bug":
net :: ERR_HTTP2_PROTOCOL_ERROR 200
In my case, it occurred on images generated by PHP.
It was at header() level, and on this one in particular:
header ('Content-Length:'. Filesize($cache_file));
It did obviously not return the exact size, so I deleted it and everything works fine now.
So Chrome checks the accuracy of the data transmitted via the headers, and if it does not correspond, it fails.
EDIT
I found why content-length via filesize was being miscalculated: the GZIP compression is active on the PHP files, so excluding the file in question will fix the problem. Put this code in the .htaccess:
SetEnvIfNoCase Request_URI ^ / thumb.php no-gzip -vary
It works and we keep the header Content-length.
I am finally able to solve this error after researching some things I thought is causing the error for 24 errors. I visited all the pages across the web. And I am happy to say that I have found the solution.
If you are using NGINX, then set gzip to off and add proxy_max_temp_file_size 0; in the server block like I have shown below.
server {
...
...
gzip off;
proxy_max_temp_file_size 0;
location / {
proxy_pass http://127.0.0.1:3000/;
....
Why? Because what actually happening was all the contents were being compressed twice and we don't want that, right?!
The fix for me was setting minBytesPerSecond in IIS to 0. This setting can be found in system.applicationHost/webLimits in IIS's Configuration Editor. By default it's set to 240.
It turns out that some web servers will cut the connection to a client if the server's data throughput to the client passes below a certain limit. This is to protect against "slow drip" denial of service attacks. However, this limit can also be triggered in cases where an innocent user requests many resources all at once (such as lots of images on a single page), and the server is forced to ration the bandwidth for each request so much that it causes one or more requests to drop below the throughput limit, which causes the server to cut the connection and shows up as net::ERR_HTTP2_PROTOCOL_ERROR in Chrome.
For example, if you request 11 GIF images all at once, and each individual GIF is 10 megabytes (11 * 10 = 110 megabytes total), and the server is only able to serve at 100 megabytes per second (per thread), the server will have to slow the throughput on the last GIF image until the first 10 are finished. If the throughput on that last GIF is slowed so much that it drops below the minBytesPerSecond limit, it will cut the connection.
I was able to resolve this by following these steps:
I used Chrome's Network Log Export tool at chrome://net-export/ to see exactly what was behind the ERR_HTTP2_PROTOCOL_ERROR error. I started the log, reproduced the error, and stopped the log.
I imported the log into the log viewer at https://netlog-viewer.appspot.com/#import, and saw an interesting event titled HTTP2_SESSION_RECV_RST_STREAM, with error code 8 (CANCEL).
I did some Googling on the term "RST_STREAM" (which appears to be an abbreviated form of "reset stream") and found a discussion between some people talking about an IIS setting called minBytesPerSecond (discussion here: https://social.msdn.microsoft.com/Forums/en-US/aeb01c46-bcdf-40ed-a417-8a3558221137). I also found another discussion where there was some debate about whether minBytesPerSecond was intended to protect against slow HTTP DoS (slow drip) attacks (discussion here: IIS 8.5 low minBytesPerSecond not working against slow HTTP POST). In any case, I learned that IIS uses minBytesPerSecond to determine whether to cancel a connection if it cannot sustain the minimum throughput. This is relevant in cases where a single user makes many requests to a large resource, and each new connection ends up starving all the other unfinished ones, to the point where some may fall below the minBytesPerSecond threshold.
To confirm that the server was canceling requests due to a minBytesPerSecond error, I checked my server's HTTPERR log at c:\windows\system32\logfiles\httperr. Sure enough, I opened the file and did a text search for "MinBytesPerSecond" and there were tons of entries for it.
So after I changed the minBytesPerSecond to 0, I was no longer able to reproduce the ERR_HTTP2_PROTOCOL_ERROR error. So, it appears that the ERR_HTTP2_PROTOCOL_ERROR error was being caused by my server (IIS) canceling the request because the throughput rate from my server fell below the minBytesPerSecond threshold.
So for all you reading this right now, if you're not using IIS, maybe there is a similar setting related to minimum throughput rate you can play with to see if it gets rid of the ERR_HTTP2_PROTOCOL_ERROR error.
I experienced a similar problem, I was getting ERR_HTTP2_PROTOCOL_ERROR on one of the HTTP GET requests.
I noticed that the Chrome update was pending, so I updated the Chrome browser to the latest version and the error was gone next time when I relaunched the browser.
I encountered this because the http2 server closed the connection when sending a big response to the Chrome.
Why?
Because it is just a setting of the http2 server, named WriteTimeout.
I had this problem when having a Nginx server that exposing the node-js application to the external world. The Nginx made the file (css, js, ...) compressed with gzip and with Chrome it looked like the same.
The problem solved when we found that the node-js server is also compressed the content with gzip. In someway, this double compressing leading to this problem. Canceling node-js compression solved the issue.
I didn't figure out what exactly was happening, but I found a solution.
The CDN feature of OVH was the culprit. I had it installed on my host service but disabled for my domain because I didn't need it.
Somehow, when I enable it, everything works.
I think it forces Apache to use the HTTP2 protocol, but what I don't understand is that there indeed was an HTTP2 mention in each of my headers, which I presume means the server was answering using the right protocol.
So the solution for my very particular case was to enable the CDN option on all concerned domains.
If anyone understands better what could have happened here, feel free to share explanations.
I faced this error several times and, it was due to transferring large resources(larger than 3MB) from server to client.
This error is currently being fixed: https://chromium-review.googlesource.com/c/chromium/src/+/2001234
But it helped me, changing nginx settings:
turning on gzip;
add_header 'Cache-Control' 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0';
expires off;
In my case, Nginx acts as a reverse proxy for Node.js application.
We experienced this problem on pages with long Base64 strings. The problem occurs because we use CloudFlare.
Details: https://community.cloudflare.com/t/err-http2-protocol-error/119619.
Key section from the forum post:
After further testing on Incognito tabs on multiple browsers, then
doing the changes on the code from a BASE64 to a real .png image, the
issue never happened again, in ANY browser. The .png had around 500kb
before becoming a base64,so CloudFlare has issues with huge lines of
text on same line (since base64 is a long string) as a proxy between
the domain and the heroku. As mentioned before, directly hitting
Heroku url also never happened the issue.
The temporary hack is to disable HTTP/2 on CloudFlare.
Hope someone else can produce a better solution that doesn't require disabling HTTP/2 on CloudFlare.
In our case, the reason was invalid header.
As mentioned in Edit 4:
take the logs
in the viewer choose Events
chose HTTP2_SESSION
Look for something similar:
HTTP2_SESSION_RECV_INVALID_HEADER
--> error = "Invalid character in header name."
--> header_name = "charset=utf-8"
By default nginx limits upload size to 1MB.
With client_max_body_size you can set your own limit, as in
location /uploads {
...
client_max_body_size 100M;
}
You can set this setting also on the http or server block instead (See here).
This fixed my issue with net::ERR_HTTP2_PROTOCOL_ERROR
Just posting here to let people know that ERR_HTTP2_PROTOCOL_ERROR in Chrome can also be caused by an unexpected response to a CORS request.
In our case, the OPTIONS request was successful, but the following PUT that should upload an image to our infrastructure was denied with a 410 (because of a missing configuration allowing uploads) resulting in Chrome issuing a ERR_HTTP2_PROTOCOL_ERROR.
When checking in Firefox, the error message was much more helpful:
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://www.[...] (Reason: CORS header ‘Access-Control-Allow-Origin’ missing). Status code: 410.
My recommendation would be to check an alternative browser in this case.
I'm not convinced this was the issue but through cPanel I'd noticed the PHP version was on 5.6 and changing it to 7.3 seemed to fix it. This was for a WordPress site. I noticed I could access images and generic PHP files but loading WordPress itself caused the error.
Seems like many issues may cause ERR_HTTP2_PROTOCOL_ERROR: in my case it was a minor syntax error in a php-generated header, Content-Type : text/plain . You might notice the space before the colon... that was it. Works no problem when the colon is right next to the header name like Content-Type: text/plain. Only took a million hours to figure out... The error happens with Chrome only, Firefox loaded the object without complaint.
If simply restarting e.g., Chrome Canary, with a fresh profile fixes the problem, then one surely
is the "victim" of a failed Chrome Variation! Yes, there are ways to opt out of being a Guinea pig in Chrome's field testing.
In my case
header params can not set null or empty string
{
'Authorization': Authorization //Authorization can't use null or ''
}
I got the same issue (asp, c# - HttpPostedFileBase) when posting a file that was larger than 1MB (even though application doesn't have any limitation for file size), for me the simplification of model class helped. If you got this issue, try to remove some parts of the model, and see if it will help in any way. Sounds strange, but worked for me.
I have been experiencing this problem for the last week now as I've been trying to send DELETE requests to my PHP server through AJAX. I recently upgraded my hosting plan where I now have an SSL Certificate on my host which stores the PHP and JS files. Since adding an SSL Certificate I no longer experience this issue. Hoping this helps with this strange error.
I also faced this error and I believe there can be multiple reasons behind it. Mine was, ARR was getting timed-out.
In my case, browser was making a request to a reverse proxy site where I have set my redirection rules and that proxy site is eventually requesting the actual site. Now for huge data it was taking more than 2 minutes 5 seconds and Application Request Routing timeout for my server was set to 2 minutes. I fixed this by increasing the ARR timeout by below steps:
1. Go to IIS
2. Click on server name
3. Click on Application Request Routing Cache in the middle pane
4. Click Server Proxy settings in right pane
5. Increase the timeout
6. Click Apply
My team saw this on a single javascript file we were serving up. Every other file worked fine. We switched from http2 back to http1.1 and then either net::ERR_INCOMPLETE_CHUNKED_ENCODING or ERR_CONTENT_LENGTH_MISMATCH. We ultimately discovered that there was a corporate filter (Trustwave) that was erroneously detecting an "infoleak" (we suspect it detected something in our file/filename that resembled a social security number). Getting corporate to tweak this filter resolved our issues.
For my situation this error was caused by having circular references in json sent from the server when using an ORM for parent/child relationships. So the quick and easy solution was
JsonConvert.SerializeObject(myObject, new JsonSerializerSettings { ReferenceLoopHandling = ReferenceLoopHandling.Ignore })
The better solution is to create DTOs that do not contain the references on both sides (parent/child).
I had another case that caused an ERR_HTTP2_PROTOCOL_ERROR that hasn't been mentioned here yet. I had created a cross reference in IOC (Unity), where I had class A referencing class B (through a couple of layers), and class B referencing class A. Bad design on my part really. But I created a new interface/class for the method in class A that I was calling from class B, and that cleared it up.
I hit this issue working with Server Sent Events. The problem was solved when I noticed that the domain name I used to initiate the connection included a trailing slash, e.g. https://foo.bar.bam/ failed with ERR_HTTP_PROTOCOL_ERROR while https://foo.bar.bam worked.
In my case (nginx on windows proxying an app while serving static assets on its own) page was showing multiple assets including 14 bigger pictures; those errors were shown for about 5 of those images exactly after 60 seconds; in my case it was a default send_timeout of 60s making those image requests fail; increasing the send_timeout made it work
I am not sure what is causing nginx on windows to serve those files so slow - it is only 11.5MB of resources which takes nginx almost 2 minutes to serve but I guess it is subject for another thread
In my case, the problem was that Bitdefender provided me with a local ssl certificate, when the website was still without a certificate.
When I disabled Bitdefender and reloaded the page, the actual valid server ssl certificate was loaded, and the ERR_HTTP2_PROTOCOL_ERROR was gone.
In my case, it was WordPress that now requires PHP 7.4 and I was running 7.2.
As soon as I updated, the errors disappeared.
Happened again and this time it was the ad-blocker that didn't like the name of my images (yt.png, ig.png, url.png). I added a prefix and all loaded ok.
In my case, the time on my computer (browser client) was out of date, synced it using settings in windows, and then the error got away
I had line breaks in my Content-Security-Policy in my nginx.conf that produced this error when used in an docker container running in Kube in GCP (serving angular but I doubt that matters).
Putting them all back on the same line and the problem went away.
A curl -v helped diagnose.
http2 error: Invalid HTTP header field was received: frame type: 1, stream: 1, name: [content-security-policy], value: [script-src 'unsafe-inline' 'self....
It was much easier to edit on separate lines but never again!

Spring RestTemplate with JDK11 errors Posting data above certain limit

I am using OAuth2RestTemplate with JDK11 to make a POST request with Json data (860 lines and 26 KB). Strangely the code works fine with < 700 Json lines (or 20 KB) on production server and with < 500 lines (15 KB) on local machine. But as soon I increase few more data blocks in the JSON it start giving exception.
Exception is based on the HttpRequestFactory implementation used with RestTemplate.
In case I use HttpComponentsClientHttpRequestFactory then it is NoHttpResponseException XXX.XXX:443 failed to respond and if I use SimpleClientHttpRequestFactory then java.net.SocketException Unexpected end of file from server
restTemplate.postForEntity(Url, dataBytes, byte[].class);
Strangely this works with lower versions of JDK 8, 9 and 10. Also I have tried other Http client like Spring Webclient with JDK11 and same data works with it. Apart from that same data also works with Curl/Postman.
But not able to identify why it is creating issue with RestTemplate beyond certain data limit.
Below are some of the main dependencies I am using (Dependency wise can't change much in existing project).
Spring-core 5.1.6.RELEASE
org.apache.httpcomponents.httpclient 4.5.6
spring-security-core 5.1.4.RELEASE
spring-security-oauth2-client 5.1.4.RELEASE
JDK11
Any help or idea will be much appreciated. TIA
I have had the same issue with the following JDK11 versions:
IMPLEMENTOR="AdoptOpenJDK"
IMPLEMENTOR_VERSION="AdoptOpenJDK"
JAVA_VERSION="11.0.2"
IMPLEMENTOR="AdoptOpenJDK"
IMPLEMENTOR_VERSION="AdoptOpenJDK"
JAVA_VERSION="11.0.4"
but the issue no longer appears in 11.0.9.11. I have not yet found what the fix was

Limit size of the REST request (GET)

I use Act.Framework for long requests, but I've noticed that the (JSON) response is truncated.
Is there any limit in the response size?
Ahmed
ActFramework does not limit response size. If you keep getting the error, please fire a bug to https://github.com/actframework/actframework with the following information:
version of actframework
java version
operations sytem
hardware info, CPU, RAM
is your app running in DEV mode or PROD mode
Better come up with a sample project that can reproduce the issue

high availability replicated servers, tomcat session lost. Firefox and chrome use 60 segs as TTL and don't respect DNS defined TTL

I have 4 servers for an http service defined on my DNS servers:
app.speednetwork.in. IN A 63.142.255.107
app.speednetwork.in. IN A 37.247.116.68
app.speednetwork.in. IN A 104.251.215.162
app.speednetwork.in. IN A 192.121.166.40
for all of them the DNS server specify a TTL (time to live) of more than 10 hours:
$ttl 38400
speednetwork.in. IN SOA plugandplay.click. info.plugandplay.click. (
1454402805
3600
3600
1209600
38400 )
Firefox ignore TTL and make a new DNS query after each 60 secs, as seen on
about:config -> network.dnsCacheExpiration 60 and on about:networking -> DNS.
Chrome shows here chrome://net-internals/#dns a correct cached dns entry, with more that 10 hours until Expired:
apis.google.com IPV4 216.58.210.174 2016-04-12 11:07:07.618 [Expired]
app.speednetwork.in IPV4 192.121.166.40 2016-04-12 21:45:36.592
but ignore this entry and every minute requery the dns as discussed https://groups.google.com/a/chromium.org/forum/#!topic/chromium-discuss/655ZTdxTftA and seen on chrome://net-internals/#events
The conclusion and the problem: every minute both browsers query dns again, receive a new IP from the 4 configured on DNS, go for a new IP/server and LOST THE TOMCAT SESSION.
As config every user browser is not an option, my question is:
1) There is some other DNS config I can use for high availability?
2) There is some http header I can use to instruct the browsers to continue using the same IP/server for the day?
The DNS TTL value is the maximum time the information may be cached. There is no minimum time, nor any requirement to cache at all. The browser behavior you describe is entirely within the DNS specs, and the browsers are doing nothing wrong. If your server solution depends on the clients remembering a DNS lookup for a certain time, then you need to redesign it. As you have already discovered, it does not work.
Building a load-balancing cluster of Tomcat servers is hardly rocket science these days, and you can easily google a solution yourself.
Keep-Alive header can make the trick. Using a large value as 65 secs, browsers reuse http connection along all session and don't try a new dns query. This is true in my app, where there is a piggyback XMLHttpRequest connection to server every minute, maybe you'll need a bigger value. Apache default is 5 secs.
On using tomcat directly:
response.setHeader("Keep-Alive", " timeout=65");
On using apache (and mod_ajp) in front of tomcat:
nano /etc/apache2/apache2.conf:
MaxKeepAliveRequests 0
KeepAliveTimeout 65
But this was not a total solution. After disconnects http connection is closed, or under several concurrent server petitions, each one is open over several servers, so results are not under the same server session.
Finally I solve this implementing CORS (cross domain), fixing a server to work with (app1, app2, etc.) and go for it until this server fails.
CORS headers on both server and client let me exchange data no matter that initial files download was from app. (IE another domain).

Server response gets cut off half way through

I have a REST API that returns json responses. Sometimes (and what seems to be at completely random), the json response gets cut off half-way through. So the returned json string looks like:
...route_short_name":"135","route_long_name":"Secte // end of response
I'm pretty sure it's not an encoding issue because the cut off point keeps changing position, depending on the json string that's returned. I haven't found a particular response size either for which the cut off happens (I've seen 65kb not get cut off, whereas 40kbs would).
Looking at the response header when the cut off does happen:
{
"Cache-Control" = "must-revalidate, private, max-age=0";
Connection = "keep-alive";
"Content-Type" = "application/json; charset=utf-8";
Date = "Fri, 11 May 2012 19:58:36 GMT";
Etag = "\"f36e55529c131f9c043b01e965e5f291\"";
Server = "nginx/1.0.14";
"Transfer-Encoding" = Identity;
"X-Rack-Cache" = miss;
"X-Runtime" = "0.739158";
"X-UA-Compatible" = "IE=Edge,chrome=1";
}
Doesn't ring a bell either. Anyone?
I had the same problem:
Nginx cut off some responses from the FastCGI backend. For example, I couldn't generate a proper SQL backup from PhpMyAdmin. I checked the logs and found this:
2012/10/15 02:28:14 [crit] 16443#0: *14534527 open()
"/usr/local/nginx/fastcgi_temp/4/81/0000004814" failed (13: Permission
denied) while reading upstream, client: *, server: , request:
"POST / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host:
"", referrer: "http://*/server_export.php?token=**"
All I had to do to fix it was to give proper permissions to the /usr/local/nginx/fastcgi_temp folder, as well as client_body_temp.
Fixed!
Thanks a lot samvermette, your Question & Answer put me on the right track.
Looked up my nginx error.log file and found the following:
13870 open() "/var/lib/nginx/tmp/proxy/9/00/0000000009" failed (13: Permission denied) while reading upstream...
Looks like nginx's proxy was trying to save the response content (passed in by thin) to a file. It only does so when the response size exceeds proxy_buffers (64kb by default on 64 bits platform). So in the end the bug was connected to my request response size.
I ended fixing my issue by setting proxy_buffering to off in my nginx config file, instead of upping proxy_buffers or fixing the file permission issue.
Still not sure about the purpose of nginx's buffer. I'd appreciate if anyone could add up on that. Is disabling the buffering completely a bad idea?
I had similar problem with cutting response from server.
It happened only when I added json header before returning response header('Content-type: application/json');
In my case gzip caused the issue.
I solved it by specifying gzip_types in nginx.conf and adding application/json to list before turning on gzip:
gzip_types text/plain text/html text/css application/x-javascript text/xml application/xml application/xml+rss text/javascript application/json;
gzip on;
It's possible you ran out of inodes, which prevents NginX from using the fastcgi_temp directory properly.
Try df -i and if you have 0% inodes free, that's a problem.
Try find /tmp -mtime 10 (older than 10 days) to see what might be filling up your disk.
Or maybe it's another directory with too many files. For example, go to /home/www-data/example.com and count the files:
find . -print | wc -l
Thanks for the question and the great answers, it saved me a lot of time. In the end, the answer of clement and sam helped me solve my issue, so the credits go to them.
Just wanted to point out that after reading a bit about the topic, it seems it is not recommended to disable proxy_buffering since it could make your server stall if the clients (user of your system) have a bad internet connection for example.
I found this discussion very useful to understand more.
The example of Francis Daly made it very clear for me:
Perhaps it is easier to think of the full process as a chain of processes.
web browser talks to nginx, over a 1 MB/s link.
nginx talks to upstream server, over a 100 MB/s link.
upstream server returns 100 MB of content to nginx.
nginx returns 100 MB of content to web browser.
With proxy_buffering on, nginx can hold the whole 100 MB, so the
nginx-upstream connection can be closed after 1 s, and then nginx can
spend 100 s sending the content to the web browser.
With proxy_buffering off, nginx can only take the content from upstream at
the same rate that nginx can send it to the web browser.
The web browser doesn't care about the difference -- it still takes 100
s for it to get the whole content.
nginx doesn't care much about the difference -- it still takes 100 s to
feed the content to the browser, but it does have to hold the connection
to upstream open for an extra 99 s.
Upstream does care about the difference -- what could have taken it 1
s actually takes 100 s; and for the extra 99 s, that upstream server is
not serving any other requests.
Usually: the nginx-upstream link is faster than the browser-nginx link;
and upstream is more "heavyweight" than nginx; so it is prudent to let
upstream finish processing as quickly as possible.
We had a similar problem. It was caused by our REST server (DropWizard) having SO_LINGER enabled. Under load DropWizard was disconnecting NGINX before it had a chance to flush it's buffers. The JSON was >8kb and the front end would receive it truncated.
I've also had this issue – JSON parsing client-side was faulty, the response was being cut off or worse still, the response was stale and was read from some random memory buffer.
After going through some guides – Serving Static Content Via POST From Nginx as well as Nginx: Fix to “405 Not Allowed” when using POST serving static while trying to configure nginx to serve a simple JSON file.
In my case, I had to use:
max_ranges 0;
so that the browser doesn't get any funny ideas when nginx adds Accept-Ranges: bytes in the response header) as well as
sendfile off;
in my server block for the proxy which serves the static files. Adding it to the location block which would finally serve the found JSON file didn't help.
Another protip for serving static JSONs would also be not forgetting the response type:
charset_types application/json;
default_type application/json;
charset utf-8;
Other searches yielded folder permission issues – nginx is cutting the end of dynamic pages and cache it or proxy buffering issues – Getting a chunked request through nginx, but that was not my case.