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Initial draft of connect production guide
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Paul Banks
Jack Pearkes
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---
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layout: "docs"
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page_title: "Connect in Production"
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sidebar_current: "docs-guides-connect-production"
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description: |-
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This guide describes best practices for running Consul Connect in production.
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---
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## Running Connect in Production
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Consul Connect can secure all inter-service communication via mutual TLS. It's
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designed to work with minimal configuration out of the box, but completing the
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[security checklist](/docs/connect/security.html) and understanding the [Consul
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security model](/docs/internals/security.html) are prerequisites for production
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deployments.
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This guide aims to walk step-by-step through a cluster setup that meets all of
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those security-related goals.
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We assume a cluster is already running with an appropriate number of servers and
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clients. To follow along with this guide in a dev environment you can follow our
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[getting started guide](/intro/getting-started/install.html). For an actual
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production cluster we expect other reference material like the
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[deployment](/docs/guides/deployment.html) and
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[performance](/docs/guides/performance.html) guides have been followed.
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The steps we need to take to get to a secure connect cluster are:
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1. [Configure ACLs](#configure-acls)
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1. [Configure Agent Transport Encryption](#configure-agent-transport-encryption)
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1. [Bootstrap Certificate Authority](#bootstrap-certificate-authority)
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1. [Setup Host Firewall](#setup-host-firewall)
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1. [Configure Service Instances](#configure-service-instances)
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## Configure ACLs
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Consul Connect's security is based on service identity. In practice the identity
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of the service is only enforcible with sufficiently restrictive ACLs.
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This section will not replace reading the full [ACL
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guide](/docs/guides/acl.html) but will highlight the specific requirements
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Connect relies on to ensure it's security properties.
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A service's identity, in the form of an x.509 certificate, will only be issued
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to an API client that has `service:write` permission for that service. In other
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words, any client that has permission to _register_ an instance of a service
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will be able to identify as that service and access all of resources that that
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service is allowed to access.
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A secure ACL setup must meet these criteria:
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1. **[ACL default
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policy](https://private-docs.consul.io/docs/agent/options.html#acl_default_policy)
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must be `deny`.** It is technically sufficient to keep default `allow` but
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add an explicit ACL denying anonymous `service:write`. Note however that in
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this case the Connect intention graph will also default to `allow` and
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explicit `deny` intentions will be needed to restrict service access. It is
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assumed for the remainder of this guide that ACL policy defaults to `deny`.
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2. **Each service must have a distinct ACL token** that is restricted to
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`service:write` only for the named service. Current Consul ACLs only support
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prefix matching but in a near-future release we will allow exact name
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matching. It is possible for all instances of the service to share the same
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token although best practices is for each instance to get a unique token as
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described below.
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### Fine Grained Enforcement
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Connect intentions manage access based only on service identity so it is
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sufficient for ACL tokens to only be unique per service and shared between
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instances.
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It is much better though if ACL tokens are unique per service _instance_ though.
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The reason for this is to limit the blast radius of a compromise.
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A future release of Connect will support revoking specific certificates that
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have been issued. For example if a single node in a datacenter has been
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compromised, it will be possible to find all certificates issued to the agent on
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that node and revoke them blocking access to the intruder without taking
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unaffected instances of the service(s) on that node offline too.
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While this will work with service-unique tokens, there is nothing stopping an
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attacker from obtaining certificates while spoofing the agent ID of another
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agent - these certificates will not appear to have been issued to the
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compromised agent and so will not be revoked. If every service instance has a
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unique token however, it will be possible to revoke all certificates that were
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requested under that token which denies access to any certificate the attacker
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could generate.
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In practice managing per-instance tokens requires automated ACL provisioning,
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for example using [HashiCorp's
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Vault](https://www.vaultproject.io/docs/secrets/consul/index.html).
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## Configure Agent Transport Encryption
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Consul's gossip (UDP) and RPC (TCP) communications need to be encrypted
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otherwise attackers may be able to see tokens and private keys while in flight
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between the server and client agents or between client agent and application.
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Follow the [encryption documentation](/docs/agent/encryption.html) to ensure
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both gossip encryption and RPC TLS are configured securely.
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## Bootstrap Certificate Authority
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Consul Connect comes with a built in Certificate Authority (CA) that will
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bootstrap by default when you first enable Connect on your servers.
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To use the built-in CA, enable it in the server's configuration.
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```text
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connect {
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enabled = true
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}
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```
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Note that server agents running in `-dev` mode have this enabled by default.
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This config change requires a restart which you can perform one server at a time
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to maintain availability in an existing cluster.
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As soon as a server that has Connect enabled becomes the leader, it will
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bootstrap a new CA and generate it's own private key which is written to the
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Raft state.
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Alternatively, an external private key can be provided via the [CA
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configuration](#TODO).
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### External CAs
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Connect has been designed with a pluggable CA component so external CAs can be
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integrated. We will expand the external CA systems that are supported in the
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future and will allow seamless online migration to a different CA or
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bootstrapping with an external CA.
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For production workloads we recommend using Vault as the CA such that the root
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key is not stored within Consul state at all.
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## Setup Host Firewall
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If using [managed proxies]() Consul will by default assign them ports from [a
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configurable range]() the default range is 20000 - 20255. If this feature is
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used, the agent assumes all ports in that range are both free to use (no other
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processes listening on them) and are exposed in the firewall to accept
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connections from other service hosts.
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TODO: could show example iptables rule but it seems kinda limited and obvious
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## Configure Service Instances
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TODO:
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- provide ACL token to API client/on disk
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- optionally configure manged proxy
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- notes about binding app only to localhost
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@ -305,6 +305,9 @@
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<li<%= sidebar_current("docs-guides-bootstrapping") %>>
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<a href="/docs/guides/bootstrapping.html">Bootstrapping</a>
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</li>
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<li<%= sidebar_current("docs-guides-connect-production") %>>
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<a href="/docs/guides/connect-production.html">Connect in Production</a>
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</li>
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<li<%= sidebar_current("docs-guides-consul-containers") %>>
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<a href="/docs/guides/consul-containers.html">Consul with Containers</a>
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</li>
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