251 lines
15 KiB
Plaintext
251 lines
15 KiB
Plaintext
---
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layout: docs
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page_title: Service Mesh Certificate Authority - Overview
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description: >-
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Consul uses a certificate authority (CA) to generate, use, manage, sign, and store certificates for your service mesh. Learn about certificate management, including configuration, root cert rotation, cross-signing, and regenerating the CA.
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---
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# Service Mesh Certificate Authority Overview
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Certificate management in Connect is done centrally through the Consul
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servers using the configured CA (Certificate Authority) provider. A CA provider
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manages root and intermediate certificates and performs certificate signing
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operations. The Consul leader orchestrates CA provider operations as necessary,
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such as when a service needs a new certificate or during CA rotation events.
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The CA provider abstraction enables Consul to support multiple systems for
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storing and signing certificates. Consul ships with a
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[built-in CA](/docs/connect/ca/consul) which generates and stores the
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root certificate and private key on the Consul servers. Consul also has
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support for using
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[Vault as a CA](/docs/connect/ca/vault). With Vault, the root certificate
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and private key material remain with the Vault cluster.
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### CA and Certificate relationship
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This diagram shows the relationship between the CA certificates in a Consul primary datacenter and a
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secondary Consul datacenter.
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Leaf certificates are created for two purposes:
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- the Leaf Cert Service is used by envoy proxies in the mesh to perform mTLS with other
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services.
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- the Leaf Cert Client Agent is created by auto-encrypt and auto-config. It is used by
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client agents for HTTP API TLS, and for mTLS for RPC requests to servers.
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Any secondary datacenters receive an intermediate certificate, signed by the Primary Root
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CA, which is used as the CA certificate to sign leaf certificates in the secondary
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datacenter.
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## CA Bootstrapping
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CA initialization happens automatically when a new Consul leader is elected
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as long as
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[Connect is enabled](/docs/connect/configuration#agent-configuration),
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and the CA system has not already been initialized. This initialization process
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will generate the initial root certificates and setup the internal Consul server
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state.
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For the initial bootstrap, the CA provider can be configured through the
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[Agent configuration](/docs/agent/config/config-files#connect_ca_config). After
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initialization, the CA can only be updated through the
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[Update CA Configuration API endpoint](/api-docs/connect/ca#update-ca-configuration).
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If a CA is already initialized, any changes to the CA configuration in the
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agent configuration file (including removing the configuration completely)
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will have no effect.
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If no specific provider is configured when Connect is enabled, the built-in
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Consul CA provider will be used and a private key and root certificate will
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be generated automatically.
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## Viewing Root Certificates
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Root certificates can be queried with the
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[list CA Roots endpoint](/api-docs/connect/ca#list-ca-root-certificates).
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With this endpoint, you can see the list of currently trusted root certificates.
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When a cluster first initializes, this will only list one trusted root. Multiple
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roots may appear as part of
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[rotation](#root-certificate-rotation).
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```shell-session
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$ curl http://localhost:8500/v1/connect/ca/roots
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{
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"ActiveRootID": "31:6c:06:fb:49:94:42:d5:e4:55:cc:2e:27:b3:b2:2e:96:67:3e:7e",
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"TrustDomain": "36cb52cd-4058-f811-0432-6798a240c5d3.consul",
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"Roots": [
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{
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"ID": "31:6c:06:fb:49:94:42:d5:e4:55:cc:2e:27:b3:b2:2e:96:67:3e:7e",
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"Name": "Consul CA Root Cert",
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"SerialNumber": 7,
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"SigningKeyID": "19:45:8b:30:a1:45:84:ae:23:52:db:8d:1b:ff:a9:09:db:fc:2a:72:39:ae:da:11:53:f4:37:5c:de:d1:68:d8",
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"ExternalTrustDomain": "a1499528-fbf6-df7b-05e5-ae81e1873fc4",
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"NotBefore": "2018-06-06T17:35:25Z",
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"NotAfter": "2028-06-03T17:35:25Z",
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"RootCert": "-----BEGIN CERTIFICATE-----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\nvC6jWPuqqMwmAiEAkvMadtwjtNU7m/AQRJrj1LeG3eXw7dWO8SlI2fEs0yY=\n-----END CERTIFICATE-----\n",
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"IntermediateCerts": null,
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"Active": true,
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"PrivateKeyType": "",
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"PrivateKeyBits": 0,
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"CreateIndex": 8,
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"ModifyIndex": 8
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}
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]
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}
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```
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## CA Configuration
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After initialization, the CA provider configuration can be viewed with the
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[Get CA Configuration API endpoint](/api-docs/connect/ca#get-ca-configuration).
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Consul will filter sensitive values from this endpoint depending on the
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provider in use, so the configuration may not be complete.
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```shell-session
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$ curl http://localhost:8500/v1/connect/ca/configuration
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{
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"Provider": "consul",
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"Config": {
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"LeafCertTTL": "72h",
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"IntermediateCertTTL": "8760h"
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},
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"CreateIndex": 5,
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"ModifyIndex": 5
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}
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```
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The CA provider can be reconfigured using the
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[Update CA Configuration API endpoint](/api-docs/connect/ca#update-ca-configuration).
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Specific options for reconfiguration can be found in the specific
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CA provider documentation in the sidebar to the left.
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## Root Certificate Rotation
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Whenever the CA's configuration is updated in a way that causes the root key to
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change, a special rotation process will be triggered in order to smoothly
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transition to the new certificate. This rotation is automatically orchestrated
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by Consul.
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~> If the current CA Provider doesn't support cross-signing, this process can't
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be followed. See [Forced Rotation Without
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Cross-Signing](#forced-rotation-without-cross-signing).
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This also automatically occurs when a completely different CA provider is
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configured (since this changes the root key). Therefore, this automatic rotation
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process can also be used to cleanly transition between CA providers. For example,
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updating Connect to use Vault instead of the built-in CA.
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During rotation, an intermediate CA certificate is requested from the new root,
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which is then cross-signed by the old root. This cross-signed certificate is
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then distributed alongside any newly-generated leaf certificates used by the
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proxies once the new root becomes active, and provides a chain of trust back to
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the old root certificate in the event that a certificate signed by the new root
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is presented to a proxy that has not yet updated its bundle of trusted root CA
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certificates to include the new root.
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After the cross-signed certificate has been successfully generated and the new root
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certificate or CA provider has been set up, the new root becomes the active one
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and is immediately used for signing any new incoming certificate requests.
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If we check the [list CA roots
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endpoint](/api-docs/connect/ca#list-ca-root-certificates) after updating the
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configuration with a new root certificate, we can see both the old and new root
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certificates are present, and the currently active root has an intermediate
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certificate which has been generated and cross-signed automatically by the old
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root during the rotation process:
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```shell-session
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$ curl localhost:8500/v1/connect/ca/roots
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{
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"ActiveRootID": "d2:2c:41:94:1e:50:04:ea:86:fc:08:d6:b0:45:a4:af:8a:eb:76:a0",
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"TrustDomain": "36cb52cd-4058-f811-0432-6798a240c5d3.consul",
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"Roots": [
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{
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"ID": "31:6c:06:fb:49:94:42:d5:e4:55:cc:2e:27:b3:b2:2e:96:67:3e:7e",
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"Name": "Consul CA Root Cert",
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"SerialNumber": 7,
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"SigningKeyID": "19:45:8b:30:a1:45:84:ae:23:52:db:8d:1b:ff:a9:09:db:fc:2a:72:39:ae:da:11:53:f4:37:5c:de:d1:68:d8",
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"ExternalTrustDomain": "a1499528-fbf6-df7b-05e5-ae81e1873fc4",
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"NotBefore": "2018-06-06T17:35:25Z",
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"NotAfter": "2028-06-03T17:35:25Z",
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"RootCert": "-----BEGIN CERTIFICATE-----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\nvC6jWPuqqMwmAiEAkvMadtwjtNU7m/AQRJrj1LeG3eXw7dWO8SlI2fEs0yY=\n-----END CERTIFICATE-----\n",
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"IntermediateCerts": null,
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"Active": false,
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"PrivateKeyType": "",
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"PrivateKeyBits": 0,
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"CreateIndex": 8,
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"ModifyIndex": 24
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},
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{
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"ID": "d2:2c:41:94:1e:50:04:ea:86:fc:08:d6:b0:45:a4:af:8a:eb:76:a0",
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"Name": "Consul CA Root Cert",
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"SerialNumber": 16238269036752183483,
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"SigningKeyID": "",
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"ExternalTrustDomain": "a1499528-fbf6-df7b-05e5-ae81e1873fc4",
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"NotBefore": "2018-06-06T17:37:03Z",
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"NotAfter": "2028-06-03T17:37:03Z",
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"RootCert": "-----BEGIN CERTIFICATE-----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\n-----END CERTIFICATE-----",
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"IntermediateCerts": [
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"-----BEGIN CERTIFICATE-----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\nAiEAwKBzEMcLd5kCBgFHNGyksRAMh/AGdEW859aL6z0u4gM=\n-----END CERTIFICATE-----\n"
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],
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"Active": true,
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"PrivateKeyType": "",
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"PrivateKeyBits": 0,
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"CreateIndex": 24,
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"ModifyIndex": 24
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}
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]
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}
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```
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The old root certificate will be automatically removed once enough time has elapsed
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for any leaf certificates signed by it to expire.
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### Forced Rotation Without Cross-Signing
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If the CA provider that is currently in use does not support cross-signing, then
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attempts to change the root key or CA provider will fail. This is to ensure
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operators don't make the change without understanding that there is additional
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risk involved.
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It is possible to force the change to happen anyway by setting the
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`ForceWithoutCrossSigning` field in the CA configuration to `true`.
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The downside is that all new certificates will immediately start being signed
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with the new root key, but it will take some time for agents throughout the
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cluster to observe the root CA change and reconfigure applications and proxies
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to accept certificates signed by this new root. This will mean connections made
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with a new certificate may fail for a short period after the CA change.
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Typically all connected agents will have observed the new roots within seconds
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even in a large deployment so the impact should be contained. But it is possible
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for a disconnected, overloaded or misconfigured agent to not see the new root
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for an unbounded amount of time during which new connections to services on that
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host will fail. The issue will resolve as soon as the agent can reconnect to
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servers.
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Currently both Consul and Vault CA providers _do_ support cross signing. As more
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providers are added this documentation will list any that this section applies
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to.
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### Recovering From Expired Certificates
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If the built-in CA provider is misconfigured or unavailable, Consul service mesh requests eventually
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stop functioning due to expiration of intermediate and root certificates. To recover manually, use the
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[CLI helper](/commands/tls/ca#consul-tls-ca-create) to generate CA certificates.
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#### Example - Regenerating the built in CA
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```shell-session
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$ consul tls ca create -cluster-id test -common-name "Consul Agent CA" -days=365 -domain consul
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==> Saved consul-agent-ca.pem
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==> Saved consul-agent-ca-key.pem
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```
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The example above generates a new CA with a validity of 365 days. The cluster-id argument is specific
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to each cluster and can be looked up by examining the `TrustDomain` field in
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the [List CA Roots](/api-docs/connect/ca#list-ca-root-certificates) endpoint.
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The contents of the generated cert and private key files from the above step should then be used with
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the [Update CA Configuration](/api-docs/connect/ca#update-ca-configuration) endpoint. Once the CA configuration is
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updated on the primary datacenter, all secondary datacenters will pick up the changes and regenerate their intermediate
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and leaf certificates, after which any new requests that require certificate verification will succeed.
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