Below is a list of changes for each TwitterServer release.

Note that PHAB_ID=# and RB_ID=# correspond to associated messages in commits.



No Changes


No Changes


  • During warmup, the /health route will respond with a more informative “warming up” message, previously an empty message was used. PHAB_ID=D949333

Runtime Behavior Changes

  • util: Bump version of logback to 1.2.11. PHAB_ID=D1026765


  • Admin HTTP server is now on Finagle’s default HTTP protocol version, which supports HTTP/1.1, HTTP/2 cleartext protocol upgrade, HTTP/2 prior-knowledge, and ALPN. PHAB_ID=D920963


No Changes


  • Update the twitter-server/slf4j-jdk14 Logging trait to ensure it defines a Logger to handle the cases where a class the trait is mixed into has redefined the logger. PHAB_ID=D854365

Runtime Behavior Changes

  • Bump version of Jackson to 2.13.2. PHAB_ID=D848592


No Changes


Runtime Behavior Changes

  • Bump version of Jackson to 2.13.1. PHAB_ID=D808049


No Changes


No Changes


No Changes


Runtime Behavior Changes

  • Bump version of Logback to 1.2.6. PHAB_ID=D742405

  • Bump version of Jackson to 2.11.4. PHAB_ID=D727879

  • Bump version of logback to 1.2.5. PHAB_ID=D729767

21.8.0 (No 21.7.0 Release)

Admin Endpoint Versions

  • Bump metric_metadata.json to version 3.2: CounterishGauge now exports with “kind”: “counterish_gauge”, instead of “counterish_gauge”: “true” PHAB_ID=D700353.

  • Bump expressions.json to version 1.1: the labels field in the Metric Metadata Expressions output to return a dictionary instead of a well-defined JSON object. However, the existing fields in labels will be preserved for now. PHAB_ID=D700065

Runtime Behavior Changes

  • Update ScalaCheck to version 1.15.4 PHAB_ID=D691691


Runtime Behavior Changes

  • Sort sublinks from Admin UI alphabetically. PHAB_ID=D684429

  • Added more information on how to enable/disable tracing in admin/tracing UI. PHAB_ID=D687337

  • Resize stack module description table based on the width of the window in Downstream Clients and Listening Servers pages in Admin UI. PHAB_ID=D686836


No Changes


  • Change Metrics Metadata Endpoint to return a histogram’s metadata when queried using the /admin/metrics.json full (suffixed) histogram name as the value for the name argument. PHAB_ID=D640725


Breaking API Changes

  • com.twitter.server.util.JsonConverter is divided into two Json mappers, JsonConverter and AdminJsonConverter. JsonConverter keeps the minimum configuration, for json mapping to/from twitter-server admin endpoints, AdminJsonConverter is configured to do so. PHAB_ID=D634550

  • Json.scala and JsonConverter are merged, removed the Json.deserialize() methods. PHAB_ID=D634550

Runtime Behavior Changes


  • Change Metrics Metadata histogram buckets field to be an object mapping from names (min, max, etc) and percentiles to the suffix for the metric name representing that portion of the histogram. Bump the endpoint’s version number to 3.0. PHAB_ID=D627870


  • Add separator_char field to the top level of the Metrics Metadata endpoint and bump the endpoints version number to 2.1. PHAB_ID=D591106


  • Escape user-provided string from the returned text. This removes a potential vector for an XSS attack. PHAB_ID=D574844


No Changes


No Changes

  • Bump version of Jackson to 2.11.2. PHAB_ID=D538440

  • Encode the request URL names in /admin/clients/<client_name> and /admin/servers/<server_name>. PHAB_ID=D540543

  • If a client connecting to an instance of TwitterServer is sending a client certificate, its expiry date (i.e. Not After) is now included as part of the information listed. PHAB_ID=D528982.

Breaking API Changes

  • Add relative_name field to metrics in the Metrics Metadata endpoint and bump the endpoints version number to 2.0. PHAB_ID=D552357


  • Check SecurityManager permissions in the ContentHandler to ensure that contention snapshotting is allowed. PHAB_ID=D531873

20.8.0 (DO NOT USE)

No Changes


Breaking API Changes

  • Make Lifecycle and Lifecycle.Warmup self-typed to TwitterServer. Lifecycle was previously self-typed to and Lifecycle.Warmup previously had no self-type restrictions. These traits can now only be mixed into instances of TwitterServer. The Lifecycle.DetatchedWarmup trait is introduced to allow users to transition to it, where they were previously extending Lifecycle.Warmup without mixing into a TwitterServer. Lifecycle.DetatchedWarmup is immediately deprecated and will be removed in a future release. PHAB_ID=D507392


No Changes


  • Make lookup of Admin LoggingHandler more resilient when multiple implementations are detected. Now instead of perhaps using an incorrect handler the server will instead emit a lint rule violation and not attempt to install a logging handler ensuring that only when a single LoggingHandler is located that the functionality is enabled. PHAB_ID=D484965

Runtime Behavior Changes

  • Bump jackson version to 2.11.0. PHAB_ID=D457496


No Changes

20.4.0 (DO NOT USE)

No Changes


No Changes


  • Add c.t.server.AbstractTwitterServer#onExitLast to allow Java users to easily register a final exit function. PHAB_ID=D433874



  • Upgrade logback to 1.2.3 PHAB_ID=D415888


  • Upgrade to jackson 2.9.10 and jackson-databind PHAB_ID=D410846

  • Multiple changes have happened around query parameter retrieval in order to remove duplicated functionality from Twitter Server that exists in Finagle. Users are encouraged to use finagle-http’s Uri class within their own code to retrieve params. PHAB_ID=D398387 * The parse method of HttpUtils has been removed. * The protected getParams method of TwitterHandler has been removed. * The signature of the getGraceParam method of ShutdownHandler has

    been changed to take a Request.

  • Add a disableAdminHttpServer property to the AdminHttpServer that can be used to prevent the AdminHttpServer from starting by default on a TwitterServer. PHAB_ID=D397925

  • The ResourceHandler companion object is no longer a JavaSingleton. PHAB_ID=D399947

  • Update ScalaTest to 3.0.8, and ScalaCheck to 1.14.0. PHAB_ID=D408331


  • Add initial support for JDK 11 compatibility. PHAB_ID=D365075

  • The endpoints section of the clients page has been fixed to no longer render an incorrect html line break tag. PHAB_ID=D391907


No Changes


  • Changed com.twitter.server.AdminHttpServer.routes from a setter to getter, use it to get all admin http server Routes. Use com.twitter.server.AdminHttpServer.addAdminRoute to add a Route and com.twitter.server.AdminHttpServer.addAdminRoutes to add many Routes. PHAB_ID=D354013



  • Upgrade to Jackson 2.9.9. PHAB_ID=D345969



  • Remove c.t.server.util.TwitterStats as it is dead code. PHAB_ID=D330013



  • Remove the TwitterServer dependency on Netty 3. PHAB_ID=D328148

New Features

  • Added an admin page, /admin/servers/connections.json with details about incoming connections, including encryption status and remote principal PHAB_ID=D329940


No Changes



  • Add DuplicateFlagDefinitions lint rule which is violated when multiple Flags with the same name are added to the underlying instance. PHAB_ID=D314410



  • Remove deprecated uses of c.t.server.ShadowAdminServer. PHAB_ID=D269149

  • Mix in the c.t.finagle.DtabFlags to allow servers to append to the “base” c.t.finagle.Dtab delegation table. Users can now call c.t.finagle.DtabFlags#addDtabs() when they want to append the parsed Flag value to the Dtab.base delegation table. Users should note to only call this method _after_ Flag parsing has occurred (which is after init and before premain).

    We also update the c.t.server.handler.DtabHandler to always return a proper JSON response of the currently configured c.t.finagle.Dtab.base. PHAB_ID=D297596


  • Change the /admin/histograms?h=…-style endpoints to return data in the same style as /admin/histograms.json. This should make it easier to use tools to parse data from either endpoint. PHAB_ID=D279779


No Changes


  • Propagate the admin server’s shutdown to the handlers that are registered with the admin server. PHAB_ID=D254656


No Changes


No Changes



  • Deprecate c.t.server.AdminHttpServer#routes. Routes should be added to the AdminHttpServer via c.t.server.AdminHttpServer#addAdminRoutes. PHAB_ID=D230247

Runtime Behavior Changes

  • Update BuildProperties to not emit a warning when no file can be located. PHAB_ID=D229586


No Changes


Runtime Behavior Changes

  • Move logic to parse the server file out the c.t.server.handler.ServerInfoHandler and into a utility object, c.t.server.BuildProperties to allow for accessing by other server logic such that the properties do not need to be re-parsed anytime access is desired. Failure to load the properties can result in the server not starting in the case of a Fatal exception being thrown. PHAB_ID=D201207

  • Update TwitterServer trait to override the inherited ShutdownTimer to be the Finagle DefaultTimer instead of the c.t.util.JavaTimer defined by default in Also update the overridden suppressGracefulShutdownErrors in TwitterServer to be a val since it is constant (instead of a def). PHAB_ID=D212896


New Features

  • Add onExit lifecycle callback to c.t.server.Hook (which is now an abstract class) to allow implemented hooks to execute functions in the App#onExit lifecycle phase. Note: c.t.server.Hook#premain now has a default implementation and requires the override modifier. PHAB_ID=D198379


No Changes


New Features

  • Added an admin page at “/admin/balancers.json” with details about client load balancers, including both configuration and current status. PHAB_ID=D171589


Runtime Behavior Changes

  • Overloaded c.t.server.AdminHttpServer#isolate to accept a Service[Request, Response]. PHAB_ID=D157891


No Changes


No Changes



  • Removed ‘finagle-zipkin-core’ as a depdendency since there was no code in twitter-server which used it. PHAB_ID=D129515


No Changes


Bug Fixes

  • Treat as an idle thread on “/admin/threads”. This method is observed when using Netty 4’s native transport. PHAB_ID=D115058


Breaking API Changes

  • Change to apply JUL log format in the c.t.server.logging.Logging trait constructor instead of in premain to apply format as early in the logging stack as possible. However, this means that users overriding the def defaultFormatter will not be able to use any flags to configure their formatting, note: the default LogFormatter does not use flags. PHAB_ID=D106534


Release Version Format

  • From now on, release versions will be based on release date in the format of YY.MM.x where x is a patch number. PHAB_ID=D101244

Runtime Behavior Changes

  • All admin endpoints except ping + healthcheck are now by-default served outside the global worker pool. PHAB_ID=D96633

Breaking API Changes

  • Rename AdminHttpServer#defaultHttpPort to AdminHttpServer#defaultAdminPort. PHAB_ID=D97394


Breaking API Changes

  • Removed code related to util-events including EventSink, JsonSink, TraceEventSink. The corresponding “/admin/events” and “/admin/events/record/” admin HTTP endpoints are also removed. PHAB_ID=D82346


No Changes


Runtime Behavior Changes

  • The admin server now waits for other registered closables to shut down before commencing its own shutdown. RB_ID=916421

Breaking API Changes

  • Removed c.t.server.Closer trait. Behavior has been moved to RB_ID=915485


No Changes



  • Bump guava to 19.0. RB_ID=907807


New Features

  • Add lint error warning on admin summary page. RB_ID=898202


Bug Fixes

  • Server graphs are now displaying again on the Twitter Server Summary page. RB_ID=898422


New Features

  • Add ability to specify admin interface UI grouping, alias, and path for admin handlers using the newly added Route and RouteUi. RB_ID=886829

Runtime Behavior Changes

  • Removed scala-xml dependency. RB_ID=890315


No Changes


No Changes


New Features

  • No longer need to add an additional resolver that points to RB_ID=878967

Runtime Behavior Changes

  • ShutdownHandler and AbortHandler accept only POST requests and ignore non-POST requests. RB_ID=848212


Bug Fixes

  • Escape user input that is rendered in HTML, and make bin/travisci publish finagle-toggle. RB_ID=848579

New Features

  • Add optional HTTP request parameter filter to /admin/registry.json allowing for simple filtering of the returned JSON. RB_ID=842784

  • Add admin endpoint, /admin/toggles, for c.t.finagle.toggle.StandardToggleMap registered Toggles. RB_ID=847434

Breaking API Changes

  • Removed AdminHttpServer#mkRoutex method. This method was created during the migration away from direct usage of netty http types and is now redundant. RB_ID=835083

  • Builds are now only for Java 8 and Scala 2.11. See the blog post for details. RB_ID=828898


Runtime Behavior Changes

  • Introduce a new lifecycle event prebindWarmup for warmup code which needs to run before the service handles traffic. GC has moved from warmupComplete to prebindWarmup. RB_ID=819411

New Features

  • Update to register TwitterServer as library in /admin/registry.json. RB_ID=825129

  • Add a FailFast lint rule for Memcached client. RB_ID=808727


New Features

  • Add AdminHttpServer#boundAddress to expose the bound address of the AdminHttpServer. RB_ID=798322


New Features

  • Add new admin endpoint “/” which redirects requests to “/admin”. RB_ID=777247





New Features

  • Add new admin endpoint “/admin/lint” which checks for possible issues with performance or configuration. RB_ID=754348

Runtime Behavior Changes

  • We no longer export a “scheduler/productivity” stat because various implementation details made it difficult to report reliably.



  • Converted to finagle-httpx. Projects that depend transitively on finagle-http through twitter-server will need to switch to finagle-httpx. RB_ID=741454 RB_ID=740731



  • Enable syntax highlighting in the docs


New Features

  • Introduce AbstractTwitterServer, a Java-friendly version of TwitterServer. RB_ID=661878


New Features

  • TwitterServer collects a statically allocated ring of runtime events, which be viewed at /admin/events, and downloaded as JSON with a HTTP client like curl (or by simply omitting the User-Agent header in the request).

  • TwitterServer exports runtime configuration data about your service, which can be downloaded as json at /admin/registry.json.


  • Bumped many dependency versions.


New Features

  • Most noticeably, the admin server received a complete UI redesign. All http endpoints are now available via a navigation pane. We provide a simple API for service owners to include ad-hoc admin pages which will be part of the navigation pane. Note, it is still possible to join the admin server’s namespace via the global com.twitter.finagle.http.HttpMuxer.

  • When using the twitter Metrics library, the admin server now scrapes your stats to extract a quick summary of how your server is performing. This includes secondly success rates for your server and least performant downstreams. We provide a /admin/metrics endpoint which can watch stats (at secondly granularity) and extract them via http queries.

  • More recently, Finagle clients and servers began to retain information about their composition. This is useful in examining the modules and parameters that comprise a specific implementation. We now surface this information in the admin server via /admin/clients/<client_name> and /admin/servers/<server_name>

  • TwitterServer now exposes a /admin/registry.json endpoint, which speaks json and exposes the values from util-registry as labels. Most labels are long-lived, and tend to represent something about a process that is true for the entire lifetime, like the version of a library, or what a flag was set to.


  • Remove dependency on mustache for admin server in favor of templating via string interpolation. This is more hygienic for web applications and frameworks built atop twitter-server.


New Features

  • Add the ability to promote objects to old gen before serving

  • Export everything from at /admin/server_info

Runtime Behavior Changes

  • Add merge_base merge_base_commit_date and scm_repository to server_info

  • AdminHttpServer now disables tracing

  • Export gauge on eden allocations

  • Improve heuristic for returning html or not in WebHandler

  • Initial redesign of admin pages

Breaking API Changes

  • Remove ServerInfo class: export /admin/server_info directly from file


  • twitter-server: Add gauge on eden allocations

  • twitter-server: Do not trace the admin http server

  • twitter-server: JvmStats needs to call Allocations.start()

  • twitter-server: Log severely if a flag is read at the wrong time

  • twitter-server: Parameterize IndexHandler on a patterns: Seq[String]

  • twitter-server: Proper resource loading in admin pages

  • twitter-server: Redesign of twitter-server admin page


  • Add admin endpoint for per-client configuration

  • Add trace ID to twitter-server logging

  • Create a logging handler for on-the-fly logging updates


  • release finagle v6.18.0

  • release util v6.18.0

  • user guide: Add blurb about filtering out stats


  • Upgrade versions of all dependencies

  • Admin dtab handler: display base dtab

  • Change productivity stat to cpuTime/wallTime


  • Bump finagle to 6.16.1-SNAPSHOT

  • Bump util to 6.16.1-SNAPSHOT

  • Disable admin server stats


  • Define type for statsReceiver explicitly so that it can be overloaded

  • Store gauge references (otherwise only weakly referenced)

  • Enforce close grace period for

  • upgrade finagle/util to 6.15.0


  • Add and replace the use of org.jboss.netty.util.CharsetUtil

  • Fix twitter-server execution test


  • upgrade finagle to 6.13.1

  • upgrade util to 6.13.2


  • upgrade finagle version to 6.13.0

  • Implement application-level shutdown handling in App.

  • Bug-fix: Refresh JVM memory snapshots on stats collection Motivation

  • Bug-fix: set content-length when responding from TwitterHandler


  • update finable to 6.12.1

  • update util to 6.12.1


  • Add logging to TwitterHandlers

  • Report on deadlock conditions in admin/contentions

  • Twitter server handler for dumping the current dtab

  • TwitterHandler: non-root logger

  • update finagle version to 6.12.0

  • update util version to 6.12.0


  • Upgrade finagle to 6.11.1

  • Upgrade util to 6.11.1


  • Remove finagle-stats dependency so that alternate stats packages can be used such as ostrich

  • Add a hooking mechanism and expose an API to install the Dtab using the hooking mechanism

  • Upgrade finagle to 6.10.0

  • Upgrade util to 6.10.0


  • Upgrade finagle to 6.8.1

  • Upgrade util to 6.8.1


  • Upgrade finagle to 6.8.0

  • Upgrade util to 6.8.0

  • Adds a cautious registration to HttpMuxer / adds a default metrics endpoint to twitter-server

  • Docs: Pointed out that you need the finagle-stats jar on your classpath

  • Sync jackson versions in twitter-server

  • Revert ordering of TwitterServer mixins.

  • Mix in Closer by default… again.


  • Support staged names introduced in Finagle

  • Add glog-style log formatting

  • Remove finagle-stats as a dependency

  • Don’t stat admin endpoints


  • Add ability to defer /health endpoint registration

  • Add new stats for current memory usage.

  • Change twitter-server admin http server flag and symbol name

  • Enable zipkin

  • Make Logging trait more flexible for easy extension

  • New scheduler “productivity” stats, dispatches.


  • bump finagle to 6.5.2

  • bump util to 6.3.8


  • bump finagle to 6.5.1

  • bump util to 6.3.7


  • Initial Release