## stable-2.9.1
This stable release contains a number of proxy enhancements: better support for
high-traffic workloads, improved performance by eliminating unnecessary endpoint
resolutions for TCP traffic and properly tearing down serverside connections
when errors occur, and reduced memory consumption on proxies which maintain many
idle connections (such as Prometheus' proxy).
On the CLI and control plane sides, it relaxes checks on root and intermediate
certificates (following X509 best practices), and fixes two issues: one that
prevented installation of the control plane into a custom namespace and one
which failed to update endpoint information when a headless service was
modified.
* Proxy:
* Addressed some issues reported around clients seeing max-concurrency errors
by increasing the default in-flight request limit to 100K pending requests
* Reduced the default idle connection timeout to 5s for outbound clients and
for inbound clients to reduce the proxy's memory footprint, especially on
Prometheus instances
* Fixed an issue where the proxy did not receive updated endpoint information
when a headless service was modified
* Added HTTP/2 keepalive PING frames
* Removed logic to avoid redundant TCP endpoint resolution
* Fixed an issue where serverside connections were not torn down when an error
occurred
* CLI / Helm / Control Plane:
* Fixed a CLI issue where the `linkerd-namespace` flag was not honored when
passed to the `install` and `upgrade` commands
* Fixed installing HA through the CLI (`linkerd install --ha`) that wasn't
honoring some of the default settings found in `values-ha.yml`
* Force the webhook pods (proxy-injector, sp-validator and tap) to be
restarted when upgrading through the CLI, if a secret they rely on changes
* Fixed multicluster installation using Helm
* Updated `linkerd check` so that it doesn't attempt to validate the subject
alternative name (SAN) on root and intermediate certificates. SANs for leaf
certificates will continue to be validated
* Fixed an issue in the destination service where endpoints always included a
protocol hint, regardless of the controller label being present or not
* Removed the `get` and `logs` command from the CLI
* No longer panic in rare cases when `linkerd-config` doesn't have an entry
for `Global` configs (thanks @hodbn!)