What is HTTP/2?
As the name suggests, it’s an iteration on HTTP 1.1 that uses binary instead of plain text. The most important difference, to my mind is:
HTTP/2 is able to run multiple streams of data over the same TCP connection, avoiding the classic HTTP 1.1 head of blocking slow request and avoiding to re-instantiate TCP connections for each request/response (KeepAlive patched the problem in HTTP 1.1 but did not fully solve it). source
In essence, this means marginally faster websites. So, naturally, I wanted this on https://parabible.com.
How to Enable HTTP/2
The first step was to check that modules/mod_http2.so module was available. Parabible is hosted on a Bitnami server. So, the path I needed to check was /opt/bitnami/apache2/modules/mod_http2.so. Hurray! It’s there…
The next step is to make sure it’s loaded. So now we edit httpd.conf (which was in my apache2 folder). Here’s the key line I needed to uncomment (presumably you need to be sure that url is correct).
LoadModule http2_module modules/mod_http2.so
Finally, you’ve got to tell Apache to use HTTP/2. According to their guide, that means something like this:
Protocols http/1.1
<VirtualHost ...>
ServerName test.example.org
Protocols h2 http/1.1
</VirtualHost>
(note that the Protocols directive[?] can be nested)
For my bitnami server, though, I didn’t have any <VirtualHost> directives. Instead, I have a /opt/bitnami/apps/parabible/conf/httpd-prefix.conf file. Now, tbh, I’m not certain the Protocols line is supposed to go in there but that’s where I put it because that’s where I found my ServerName directive.
I used Protocols h2 http/1.1. This tells Apache to prefer h2 to HTTP/1. There is another HTTP/2 code—h2c. But, h2c does not require TLS and since everyone should be using TLS (and a lot of browsers don’t even support HTTP/2 if it’s not over TLS), h2 is preferable.
And voila, now I see “HTTP/2” all the way down my “Protocol” column in the dev tools. Success… Now to benchmark the performance changes.