One of the key features of Apache Traffic Server™ is its modularity. Features that aren’t needed in the core simply aren’t there. This helps to provide an additional guarantee that our core can remain fast by concentrating on the things that we always provide: caching and proxying.

All other functionality can be moved into plugins and by offering a consistent C API, everyone can implement their own functionality, without having to touch the core.

Stable plugins

Plugins that are considered stable are installed by default in Traffic Server releases.

Delegates the authorization decision of a request to an external HTTP service.
AWS S3 Authentication
Support for Amazon S3 authentication features.
Background Fetch
Proactively fetch content from Origin in a way that it will fill the object into cache.
Cache Key and Parent Selection URL Manipulation
Allows some common cache key or parent selection URL manipulations based on various HTTP request elements.
Cache Promotion Policies
Allows for control over which assets should be written to cache, or not.
Combo Handler
Provides an intelligent way to combine multiple URLs into a single URL, and have Apache Traffic Server combine the components into one response.
Configuration Remap
Override configuration directives on a per-rule basis.
Implements the Edge Side Includes (ESI) specification.
Escalate: when the origin returns specific status codes, retry the request at a secondary origin (failover/fail-action)
Generate arbitrary response data.
Compress or deflate cache responses.
Header Rewrite
Modify requests and responses based on incoming and outgoing headers and other transaction attributes.
Health Checks
Define service health check links.
Allows plugins to be written in Lua instead of C code.
Regex Remap
Configure remapping rules using regular expressions.
Regex Revalidate
Configurable rules for forcing cache object revalidations using regular expressions.
Slice full file or range based requests into deterministic chunks, allowing large files to be spread across multiple cache stripes. Allows range requests to be satisfied by stitching these chunks together.
Stats over HTTP
Provide an HTTP interface to all Traffic Server statistics.
Log TCP metrics at various points of the HTTP processing pipeline.
Allows HTTP clients to debug the operation of the Traffic Server cache using the X-Debug header.

Experimental plugins

Plugins that are considered experimental are located in the plugins/experimental directory of the Traffic Server source tree. Experimental plugins can be compiled by passing the –enable-experimental-plugins option to configure:

$ autoconf -i
$ ./configure --enable-experimental-plugins
$ make
Access Control
Access control plugin that handles various access control use-cases.
Balances requests across multiple origin servers.
Buffer Upload
Buffers POST data before connecting to the Origin server.
Manages and/or generates certificates for incoming HTTPS requests.
Allows to Collapse multiple Concurrent requests by downloading once from the Origin and serving all clients in parallel.
FQ Pacing
FQ Pacing: Rate Limit TCP connections using Linux’s Fair Queuing queue discipline
Deny or allow requests based on the source IP geo-location.
Header Frequency
Count the frequency of headers.
Adds support for HTTP Pipes.
Implements the memcache protocol for cache contents.
Implements the Metalink download description format in order to try not to download the same file twice.
Money Trace
Allows Trafficserver to participate in a distributed tracing system based upon the Comcast Money library.
MP4 streaming media.
Multiplex inbound requests to multiple upstream destinations. This is useful for requests that are beacons or other metric gathering requests, to report to multiple upstreams. Alternatively this can be used to do A/B testing by sending a duplicated slice of inbound production traffic to experimental upstreams.
MySQL Remap
Allows dynamic remaps from a MySQL database.
Pre-fetch objects based on the requested URL path pattern.
Remap Purge
This remap plugin allows the administrator to easily setup remotely controlled PURGE for the content of an entire remap rule.
Signed URLs
Adds support for verifying URL signatures for incoming requests to either deny or redirect access.
SSL Headers
Populate request headers with SSL session information.
System Stats
Inserts system statistics in to the stats list
Traffic Dump
Dumps traffic data into a JSON format file which can be used to replay traffic.
WebP Transform
Converts jpeg and png images to webp format.