• These are the highlights of new features or additions to existing features in v5.0.x and 5.1.x. For the complete list of all changes see this JIRA Release Notes.

New configuration options

• You can now force unsatisfiable Range: requests to go to origin even when read-while-writer is in effect. This can help avoid significant latency on large objects. The setting is overloaded on the existing proxy.config.cache.enable_read_while_writer configuration.

Jira: TS-2314, 

TLS

We continue to improve our TLS (HTTPS) features and support. Noteworthy in 5.2.x is:

• SSLv3 is now disabled by default!
• Dynamic TLS record size tuning. According to Ilya, this makes us the first server that is all Green. 
• Add forward secrecy support with DHE.
• Add ssl_pre_handshake hook for better plugin access to SSL handling.
• Improved session cache, for better performance and scalability.
• New configuration for OpenSSL session cache, proxy.config.ssl.session_cache.auto_clear.

...

The following improvements were made to existing plugins:

• The header_rewrite plugin no longer requires the Boost libraries.
• The stats_over_http plugin will now emit JSON numbers.
• The background_fetch plugin can now be controlled per remap-rule.

New following additions were also done to plugins:

• The mySQL remap plugin now actually builds, as part of experimental. This is technically not a new plugin, but it would not build before.

Jira: TS-2119, TS-3068, TS-3071, TS-2682, 

Plugin APIs

The following additions were made to the plugin APIs:

...