Unit 1.23.0 Released§


I’m glad to announce a new release of NGINX Unit.

Nowadays, TLS is everywhere, while plain HTTP is almost nonexistent in the global network. We are fully aware of this trend and strive to simplify TLS configuration in Unit as much as possible. Frankly, there’s still much to do, but the introduction of smart SNI certificate selection marks yet another step in this direction.

Perhaps, you already know about Unit’s certificate storage API that uploads certificate bundles to a running instance. Otherwise, if you’re not yet fully informed but still curious, here’s a decent overview:

Basically, you just upload a certificate chain and a key under some name; after that, you can specify the name (mycert in the example below) with any listening socket to configure it for HTTPS:

    "listeners": {
        "*:443": {
            "tls": {
                "certificate": "mycert"

            "pass": "routes"

Unit’s API also enables informative introspection of uploaded certificate bundles so you can monitor their validity and benefit from service discovery.

You can also upload any number of certificate bundles to switch between them on the fly without restarting the server (yes, Unit’s dynamic nature is exactly like that). Still, with this release, there are even more options, as you can supply any number of certificate bundle names with a listener socket:

    "certificate": [ "mycertA", "mycertB", ... ]

For each client, Unit automatically selects a suitable certificate from the list depending on the domain name the client connects to (and therefore supplies via the “Server Name Indication” TLS extension). Thus, you don’t even need to care about matching certificates to server names; Unit handles that for you. As a result, there’s almost no room for a mistake, which spares more time for stuff that matters.

As one can reasonably expect, you can always add more certs, delete them, or edit the cert list on the fly without compromising performance. That’s the Unit way!

In case you’re wondering whom to thank for this shiny new feature: give a warm welcome to Andrey Suvorov, a new developer on our team. He will continue working on TLS improvements in Unit, and his TODO list is already stacked. Still, if you’d like to suggest a concept or have a particular interest in some feature, just start a ticket on GitHub; we are open to your ideas:

Also, plenty of solid bug fixing work was done by the whole team. See the full change log below:

Changes with Unit 1.23.0                                         25 Mar 2021

    *) Feature: support for multiple certificate bundles on a listener via
       the Server Name Indication (SNI) TLS extension.

    *) Feature: "--mandir" ./configure option to specify the directory for
       man page installation.

    *) Bugfix: the router process could crash on premature TLS connection
       close; the bug had appeared in 1.17.0.

    *) Bugfix: a connection leak occurred on premature TLS connection close;
       the bug had appeared in 1.6.

    *) Bugfix: a descriptor and memory leak occurred in the router process
       when processing small WebSocket frames from a client; the bug had
       appeared in 1.19.0.

    *) Bugfix: a descriptor leak occurred in the router process when
       removing or reconfiguring an application; the bug had appeared in

    *) Bugfix: persistent storage of certificates might've not worked with
       some filesystems in Linux, and all uploaded certificate bundles were
       forgotten after restart.

    *) Bugfix: the controller process could crash while requesting
       information about a certificate with a non-DNS SAN entry.

    *) Bugfix: the controller process could crash on manipulations with a
       certificate containing a SAN and no standard name attributes in
       subject or issuer.

    *) Bugfix: the Ruby module didn't respect the user locale for defaults
       in the Encoding class.

    *) Bugfix: the PHP 5 module failed to build with thread safety enabled;
       the bug had appeared in 1.22.0.

Other notable features we are working on include:

  • statistics API
  • process control API
  • chrooting on a per-request basis during static file serving
  • MIME types filtering for static files
  • configuring ciphers and other OpenSSL settings

So much more to come!

Also, if you’d like to know more about Unit and prefer watching fun videos instead of reading tedious documentation, I’m happy to recommend Timo Stark, our own PM Engineer. Recently, he started regularly streaming on Twitch and YouTube:

Tomorrow (March 26), at 10 p.m. CET (or 2 p.m. PDT), he is going on air to livestream his using Unit’s brand-new SNI feature to automate the certbot setup:

Everyone is welcome!

wbr, Valentin V. Bartenev