1.4.4

Linkerd 1.4.4 continues our focus on diagnostics, performance, and stability. This release features
several performance and diagnostics improvements, including better handling of HTTP/2 edge cases,
new watch state introspection for the Consul namer, and better isolation of admin page serving from
the primary data path. It also features a new, pluggable trace propagation module that allows for
easier integration with tracing systems like OpenTracing.

This release features contributions from Salesforce, Walmart, WePay, Comcast, ScalaConsultants,
OfferUp, Buoyant, and more. A big thank you to:

• Chris Goffinet
• Dan Vulpe
• Ivano Pagano
• Leo Liang
• Mantas Stoškus
• Mohsen Rezaei
• Nick K
• Priyasmita Bagchi
• Robert Panzer
• Ryan Michela

Full release notes:

• Distributed Tracing
  • Refactor Linkerd's trace propagation module to be pluggable. This allows better integration with
    tracing systems like OpenTracing and allows users to write Linkerd trace propagation plugins for
    arbitrary tracing systems.
• TLS
  • Deprecate the trustCerts config field in the client TLS section in favor of
    trustCertsBundle. This allows you to use multiple trust certs in one file and avoids the need
    for Linkerd to create temporary files.
• HTTP, HTTP/2
  • Fix an issue where Linkerd sometimes interprets HTTP/1.0 response with no Content-Length as a
    chunked response.
  • Improve error messages by adding contextual routing information to a ConnectionFailed
    exception sent back to a client via Linkerd.
  • Add a gRPC standard-compliant response classifier.
  • Fix an issue where Linkerd doesn't add an l5d-err header in an HTTP/2 response.
  • Fix an issue where Linkerd does not handle HTTP/2 requests with invalid HTTP status codes
    correctly.
• Consul
  • Add new watch state instrumentation feature to the io.l5d.consul namer.
  • Fix an issue where the io.l5d.consul namer sometimes does not retry ConnectionRefused
    exception.
  • Fix an issue where the io.l5d.consul namer returns a single IP for a service node instead of
    multiple IP addresses for a service node.
• Admin
  • Fix an issue where Linkerd may slow down data plane requests when the admin server is under
    heavy load.
  • Improve performance of the Prometheus telemeter when serving metrics for a high cardinality
    of services.
  • Fix an issue where the intepreter_state endpoint was not available for interpreters that
    contained a transformer.
  • Fix the namer_state endpoint to expose namers that use transformers.
• Namerd
  • Fix an issue where null values were accepted by the Dtab HTTP API.