mirror of https://github.com/hashicorp/consul
83 lines
4.4 KiB
Markdown
83 lines
4.4 KiB
Markdown
---
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layout: intro
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page_title: Consul vs. Istio
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sidebar_title: 'Istio'
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sidebar_current: vs-other-istio
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description: >-
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Istio is a platform for connecting and securing microservices. This page
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describes the similarities and differences between Istio and Consul.
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---
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# Consul vs. Istio
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Istio is an open platform to connect, manage, and secure microservices.
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To enable the full functionality of Istio, multiple services must
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be deployed. For the control plane: Pilot, Mixer, and Citadel must be
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deployed and for the data plane an Envoy sidecar is deployed. Additionally,
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Istio requires a 3rd party service catalog from Kubernetes, Consul, Eureka,
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or others. Finally, Istio requires an external system for storing state,
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typically etcd. At a minimum, three Istio-dedicated services along with at
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least one separate distributed system (in addition to Istio) must be
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configured to use the full functionality of Istio.
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Istio provides layer 7 features for path-based routing, traffic shaping,
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load balancing, and telemetry. Access control policies can be configured
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targeting both layer 7 and layer 4 properties to control access, routing,
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and more based on service identity.
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Consul is a single binary providing both server and client capabilities, and
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includes all functionality for service catalog, configuration, TLS certificates,
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authorization, and more. No additional systems need to be installed to use
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Consul, although Consul optionally supports external systems such as Vault
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to augment behavior. This architecture enables Consul to be easily installed
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on any platform, including directly onto the machine.
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Consul uses an agent-based model where each node in the cluster runs a
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Consul Client. This client maintains a local cache that is efficiently updated
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from servers. As a result, all secure service communication APIs respond in
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microseconds and do not require any external communication. This allows us to
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do connection enforcement at the edge without communicating to central
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servers. Istio flows requests to a central Mixer service and must push
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updates out via Pilot. This dramatically reduces the scalability of Istio,
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whereas Consul is able to efficiently distribute updates and perform all
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work on the edge.
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Consul provides layer 7 features for path-based routing, traffic shifting,
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load balancing, and telemetry. Consul enforces authorization and identity to
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layer 4 only — either the TLS connection can be established or it can't.
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We believe service identity should be tied to layer 4, whereas layer 7 should be
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used for routing, telemetry, etc. We will be adding more layer 7 features to Consul in the future.
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The data plane for Consul is pluggable. It includes a built-in proxy with
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a larger performance trade off for ease of use. But you may also use third
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party proxies such as Envoy to leverage layer 7 features. The ability to use the
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right proxy for the job allows flexible heterogeneous deployments where
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different proxies may be more correct for the applications they're proxying. We
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encourage users leverage the pluggable data plane layer and use a proxy which
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supports the layer 7 features necessary for the cluster.
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In addition to third party proxy support, applications can natively integrate
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with the Connect protocol. As a result, the performance overhead of introducing
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Connect is negligible. These "Connect-native" applications can interact with
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any other Connect-capable services, whether they're using a proxy or are
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also Connect-native.
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Consul implements automatic TLS certificate management complete with rotation
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support. Both leaf and root certificates can be rotated automatically across
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a large Consul cluster with zero disruption to connections. The certificate
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management system is pluggable through code change in Consul and will be
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exposed as an external plugin system shortly. This enables Consul to work
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with any PKI solution.
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Because Consul's service connection feature "Connect" is built-in, it
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inherits the operational stability of Consul. Consul has been in production
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for large companies since 2014 and is known to be deployed on as many as
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50,000 nodes in a single cluster.
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This comparison is based on our own limited usage of Istio as well as
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talking to Istio users. If you feel there are inaccurate statements in this
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comparison, please click "Edit This Page" in the footer of this page and
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propose edits. We strive for technical accuracy and will review and update
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this post for inaccuracies as quickly as possible.
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