90 lines
2.5 KiB
Plaintext
90 lines
2.5 KiB
Plaintext
---
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layout: docs
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page_title: Sentinel in Consul
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description: >-
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Consul Enterprise uses Sentinel to augment the built-in ACL system to provide
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advanced policy enforcement. Sentinel policies can currently execute on KV
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modify and service registration.
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---
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# Sentinel Overview
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<EnterpriseAlert />
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Consul 1.0 adds integration with [Sentinel](https://hashicorp.com/sentinel) for policy enforcement.
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Sentinel policies help extend the ACL system in Consul beyond the static "read", "write", and "deny"
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policies to support full conditional logic and integration with external systems.
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## Sentinel in Consul
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Sentinel policies are applied during writes to the KV Store.
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An optional `sentinel` field specifying code and enforcement level can be added to [ACL policy definitions](/docs/agent/acl-rules#sentinel-integration) for Consul KV. The following policy ensures that the value written during a KV update must end with "dc1".
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```text
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key "datacenter_name" {
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policy = "write"
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sentinel {
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code = <<EOF
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import "strings"
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main = rule { strings.has_suffix(value, "dc1") }
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EOF
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enforcementlevel = "soft-mandatory"
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}
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}
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```
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If the `enforcementlevel` property is not set, it defaults to "hard-mandatory".
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## Imports
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Consul imports all the [standard imports](https://docs.hashicorp.com/sentinel/imports/) from Sentinel _except_ [`http`](https://docs.hashicorp.com/sentinel/imports/http/). All functions in these imports are available to be used in policies.
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## Injected Variables
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Consul passes some context as variables into Sentinel, which are available to use inside any policies you write.
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#### Variables injected during KV store writes
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| Variable Name | Type | Description |
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| ------------- | -------- | ---------------------- |
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| `key` | `string` | Key being written |
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| `value` | `string` | Value being written |
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| `flags` | `uint64` | [Flags](/api/kv#flags) |
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## Sentinel Examples
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The following are two examples of ACL policies with Sentinel rules.
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### Required Key Suffix
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Any values stored under the key prefix "dc1" must end with "dev"
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```text
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key "dc1" {
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policy = "write"
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sentinel {
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code = <<EOF
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import "strings"
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main = rule { strings.has_suffix(value, "dev") }
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EOF
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}
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}
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```
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### Restricted Update Time
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The key "haproxy_version" can only be updated during business hours.
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```text
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key "haproxy_version" {
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policy = "write"
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sentinel {
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code = <<EOF
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import "time"
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main = rule { time.now.hour > 8 and time.now.hour < 17 }
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EOF
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}
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}
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```
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