Plugins

Overview

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.

AuthProxy: 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.
Cache Range Requests: Cache ranges by adding the range request header to the cache key.
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.
ESI: Implements the Edge Side Includes (ESI) specification.
Escalate: Escalate: when the origin returns specific status codes, retry the request at a secondary origin (failover/fail-action)
Generator: Generate arbitrary response data.
Compress: 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.
HTTP Stats: A remap-based plugin that provides an HTTP interface to all Traffic Server statistics.
Lua: 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.
Stats over HTTP: Provide an HTTP interface to all Traffic Server statistics.
TCPInfo: Log TCP metrics at various points of the HTTP processing pipeline.
XDebug: 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.
Block Errors: Blocks or downgrades new connections when the server receives too many errors from an IP address.
Certifier: Manages and/or generates certificates for incoming HTTPS requests.
Cert Reporting Tool: Examines and logs information on loaded certificates.
Collapsed-Forwarding: 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
GeoIP ACL: Deny or allow requests based on the source IP geo-location.
Header Frequency: Count the frequency of headers.
ICAP: Pass response data to external server for further processing using the ICAP protocol.
JA3 Fingerprint: Calculates JA3 Fingerprints for incoming SSL traffic.
MaxMind ACL: ACL based on the maxmind geo databases (GeoIP2 mmdb and libmaxminddb)
Memcache: Implements the memcache protocol for cache contents.
Metalink: 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: MP4 streaming media.
Multiplexer: 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.
OpenTelemetry Tracer: Allows Trafficserver to participate in OpenTelemetry distributed tracing system
Prefetch: Pre-fetch objects based on the requested URL path pattern.
Parent Select: This remap plugin allows selection of parent proxies or origins during requests. This provides the same functionality as the core parent.config and strategies.yaml config files.
Rate Limit: Simple transaction rate limiting.
Remap Stats: This global plugin adds remap stats to the stats.
Remap Purge: This remap plugin allows the administrator to easily setup remotely controlled PURGE for the content of an entire remap rule.
URI Signing: Adds support for verifying URL signatures for incoming requests to either deny or redirect access, implementing the IETF URI Signing draft RFC.
Legacy Signed URLs: Adds support for verifying URL signatures for incoming requests to either deny or redirect access.

Note

URL Sig is old and unlikely to be standardized. Prefer URI Signing.
Slice: Slice full file or range based requests into deterministic chunks, allowing large files to be spread across multiple cache stripes. Allows arbitrary range requests to be satisfied by stitching these chunks together.
SSL Session Reuse: Coordinates Session ID and ticket based TLS session resumption between a group of ATS machines.
SSL Headers: Populate request headers with SSL session information.
STEK Share: Coordinates STEK (Session Ticket Encryption Key) between ATS instances running in a group.
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.