The Istio service mesh continues its quarterly release cadence with version 1.6. After major changes in release 1.5 to the control plane architecture, notably moving from a set of microservices to a monolithic Istiod service, and the introduction of a new, unified model for extending Istio and its Envoy proxies using WebAssembly, Istio 1.6 may seem tame in comparison, but it still offers a large number of smaller enhancements with a focus on operability. We will look at several of the highlights.
Installation and Configuration Management
Canary Support for Istio Upgrades
In order to reduce risk when performing version upgrades of the Istio control plane in a production cluster, users can now deploy multiple releases of Istiod in the same cluster and gradually migrate pods to the newer version. The
istioctl command-line tool supports assigning names to versions when installing new control plane versions. These names can then be used to assign workloads to a specific Istiod version running in the service mesh.
Istio Operator Support for Remote Control Planes
The Istio Operator and its Custom Resource Definition (CRD),
IstioOperator, now support the experimental ability to configure the data plane (Envoy proxy sidecar mesh) in one Kubernetes cluster to use the control plane (Istiod) in a remote cluster. A single control plane can support managing the data planes in multiple meshes.
preview Installation Profile for Experimental Features
istioctl now supports a
preview installation profile. This new profile enables experimental features to make it easier for users to try them.
Helm Installation Removed
istioctl and the operator still use Helm charts under the hood, release 1.6 removes the previously-deprecated support for users to deploy and manage their Istio meshes by using the
helm command-line tool directly.
Route Configuration Delegation for
VirtualService resource now has an optional
delegate parameter for HTTP path-based routes. This feature can be used as a kind of “namespace” boundary when defining a number of routes for one service.
For example, your service architecture may have a single endpoint which acts as a portal for multiple backends. Requests matching
https://portal.example.com/login may go to an authentication service.
https://portal.example.com/search requests would route to a search index frontend. A payment service may handle requests for
https://portal.example.com/checkout. These services are probably each managed by a separate team that needs permission to update the configuration for their endpoints but for no one else’s. In this case, cluster admins could create one top-level
VirtualService object for
portal.example.com which then delegates the configuration details for each of the URI paths to three separate
VirtualService objects. Kubernetes RBAC roles for each team could then grant them permission to change only their endpoint’s
VirtualService object’s specification.
WorkloadEntry for External Workloads
Release 1.6 adds a new resource type,
WorkloadEntry, to support workloads which lie outside an Istio mesh’s Kubernetes cluster. Users can install Envoy proxies on their virtual or physical servers to allow the workloads on these hosts to join an Istio mesh, enabling seamless interaction with all the workloads in the mesh.
Customized Proxy Configurations for Workloads
Users can now override the default configuration for their mesh’s default Envoy proxy on a per-workload basis by adding the annotation
proxy.istio.io/config to the workload’s
PodSpec and setting to an inline
The Istio control plane workloads and proxies now all have default annotations to configure metric scraping by Prometheus. Note that the defaults are set to work when installing Prometheus with
istioctl. This Prometheus configuration does not have application security features enabled. You should consider directly managing Prometheus in your production clusters to ensure its security and scalability.
Istio telemetry version 2 adds support for metrics customization options. Users can configure metric labels based on connection request and response attributes.
Istio 1.6 may not be quite as flashy as the monumental 1.5 release, but it still offers a number of solid improvements that add useful features to Istio while simultaneously improving its operability experience.