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300 lines
12 KiB
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300 lines
12 KiB
Plaintext
---
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layout: docs
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page_title: Cloud Foundry - Auth Methods
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description: The cf auth method allows automated authentication of Cloud Foundry instances.
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---
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# Cloud Foundry (CF) Auth Method
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The `cf` auth method provides an automated mechanism to retrieve a Vault token
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for CF instances. It leverages CF's [App and Container Identity Assurance](https://content.pivotal.io/blog/new-in-pcf-2-1-app-container-identity-assurance-via-automatic-cert-rotation).
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At a high level, this works as follows:
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1. You construct a request to Vault including your `CF_INSTANCE_CERT`, signed by your `CF_INSTANCE_KEY`.
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2. Vault validates that the signature is no more than 300 seconds old, or 60 seconds in the future.
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3. Vault validates that the cert was issued by the CA certificate you've pre-configured.
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4. Vault validates that the request was signed by the private key for the `CF_INSTANCE_CERT`.
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5. Vault validates that the `CF_INSTANCE_CERT` application ID, space ID, and org ID presently exist.
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6. If all checks pass, Vault issues an appropriately-scoped token.
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## Known Risks
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This authentication engine uses CF's instance identity service to authenticate users to Vault. Because
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CF makes its CA certificate and private key available to certain users at any time, it's possible for
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someone with access to them to self-issue identity certificates that meet the criteria for a Vault role,
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allowing them to gain unintended access to Vault.
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For this reason, we recommend that if you enable this auth method, you carefully guard access to the
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private key for your instance identity CA certificate. In CredHub, it can be obtained through the
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following call: `$ credhub get -n /cf/diego-instance-identity-root-ca`.
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Take extra steps to limit access to that path in CredHub, whether it be through use of CredHub's ACL
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system, or through carefully limiting the users who can access CredHub.
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## Usage
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### Preparing to Configure the Plugin
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To configure this plugin, you'll need to gather the CA certificate that CF uses to issue each `CF_INSTANCE_CERT`,
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and you'll need to configure it to access the CF API.
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To gain your instance identity CA certificate, in the [cf dev](https://github.com/cloudfoundry-incubator/cfdev)
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environment it can be found using:
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```shell-session
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$ bosh int --path /diego_instance_identity_ca ~/.cfdev/state/bosh/creds.yml
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```
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In environments containing Ops Manager, it can be found in CredHub. To gain access to CredHub, first install
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[the PCF command-line utility](https://docs.pivotal.io/tiledev/2-2/pcf-command.html) and authenticate to it
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using the `metadata` file it describes. These instructions also use [jq](https://stedolan.github.io/jq/) for
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ease of drilling into the particular part of the response you'll need.
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Once those steps are complete, get the credentials you'll use for CredHub:
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```shell-session
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$ pcf settings | jq '.products[0].director_credhub_client_credentials'
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```
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SSH into your Ops Manager VM:
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```shell-session
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$ ssh -i ops_mgr.pem ubuntu@$OPS_MGR_URL
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```
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Please note that the above OPS_MGR_URL shouldn't be prepended with `https://`.
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Log into CredHub with the credentials you obtained earlier:
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```shell-session
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$ credhub login --client-name=director_to_credhub --client-secret=some-secret
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```
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And view the root certificate CF uses to issue instance identity certificates:
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```shell-session
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$ credhub get -n /cf/diego-instance-identity-root-ca
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```
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The output to that call will include two certificates and one RSA key. You will need to copy the certificate
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under `ca: |` and place it into a file on your local machine that's properly formatted. Here's an example of
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a properly formatted CA certificate:
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```shell-session
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$ cat ca.crt
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-----BEGIN CERTIFICATE-----
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MIIDNDCCAhygAwIBAgITPqTy1qvfHNEVuxsl9l1glY85OTANBgkqhkiG9w0BAQsF
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ADAqMSgwJgYDVQQDEx9EaWVnbyBJbnN0YW5jZSBJZGVudGl0eSBSb290IENBMB4X
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DTE5MDYwNjA5MTIwMVoXDTIyMDYwNTA5MTIwMVowKjEoMCYGA1UEAxMfRGllZ28g
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SW5zdGFuY2UgSWRlbnRpdHkgUm9vdCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEP
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ADCCAQoCggEBALa8xGDYT/q3UzEKAsLDajhuHxPpIPFlCXwp6u8U5Qrf427Xof7n
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rXRKzRu3g7E20U/OwzgBi3VZs8T29JGNWeA2k0HtX8oQ+Wc8Qngz9M8t1h9SZlx5
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fGfxPt3x7xozaIGJ8p4HKQH1ZlirL7dzun7Y+7m6Ey8cMVsepqUs64r8+KpCbxKJ
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rV04qtTNlr0LG3yOxSHlip+DDvUVL3jSFz/JDWxwCymiFBAh0QjG1LKp2FisURoX
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GY+HJbf2StpK3i4dYnxQXQlMDpipozK7WFxv3gH4Q6YMZvlmIPidAF8FxfDIsYcq
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TgQ5q0pr9mbu8oKbZ74vyZMqiy+r9vLhbu0CAwEAAaNTMFEwHQYDVR0OBBYEFAHf
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pwqBhZ8/A6ZAvU+p5JPz/omjMB8GA1UdIwQYMBaAFAHfpwqBhZ8/A6ZAvU+p5JPz
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/omjMA8GA1UdEwEB/wQFMAMBAf8wDQYJKoZIhvcNAQELBQADggEBADuDJev+6bOC
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v7t9SS4Nd/zeREuF9IKsHDHrYUZBIO1aBQbOO1iDtL4VA3LBEx6fOgN5fbxroUsz
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X9/6PtxLe+5U8i5MOztK+OxxPrtDfnblXVb6IW4EKhTnWesS7R2WnOWtzqRQXKFU
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voBn3QckLV1o9eqzYIE/aob4z0GaVanA9PSzzbVPsX79RCD1B7NmV0cKEQ7IrCrh
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L7ElDV/GlNrtVdHjY0mwz9iu+0YJvxvcHDTERi106b28KXzJz+P5/hyg2wqRXzdI
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faXAjW0kuq5nxyJUALwxD/8pz77uNt4w6WfJoSDM6XrAIhh15K3tZg9EzBmAZ/5D
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jK0RcmCyaXw=
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-----END CERTIFICATE-----
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```
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An easy way to verify that your CA certificate is properly formatted is using OpenSSL like so:
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```shell-session
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$ openssl x509 -in ca.crt -text -noout
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Certificate:
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Data:
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Version: 3 (0x2)
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Serial Number:
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3e:a4:f2:d6:ab:df:1c:d1:15:bb:1b:25:f6:5d:60:95:8f:39:39
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Signature Algorithm: sha256WithRSAEncryption
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Issuer: CN=Diego Instance Identity Root CA
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Validity
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Not Before: Jun 6 09:12:01 2019 GMT
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Not After : Jun 5 09:12:01 2022 GMT
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Subject: CN=Diego Instance Identity Root CA
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Subject Public Key Info:
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Public Key Algorithm: rsaEncryption
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Public-Key: (2048 bit)
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Modulus:
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00:b6:bc:c4:60:d8:4f:fa:b7:53:31:0a:02:c2:c3:
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6a:38:6e:1f:13:e9:20:f1:65:09:7c:29:ea:ef:14:
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e5:0a:df:e3:6e:d7:a1:fe:e7:ad:74:4a:cd:1b:b7:
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83:b1:36:d1:4f:ce:c3:38:01:8b:75:59:b3:c4:f6:
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f4:91:8d:59:e0:36:93:41:ed:5f:ca:10:f9:67:3c:
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42:78:33:f4:cf:2d:d6:1f:52:66:5c:79:7c:67:f1:
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3e:dd:f1:ef:1a:33:68:81:89:f2:9e:07:29:01:f5:
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66:58:ab:2f:b7:73:ba:7e:d8:fb:b9:ba:13:2f:1c:
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31:5b:1e:a6:a5:2c:eb:8a:fc:f8:aa:42:6f:12:89:
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ad:5d:38:aa:d4:cd:96:bd:0b:1b:7c:8e:c5:21:e5:
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8a:9f:83:0e:f5:15:2f:78:d2:17:3f:c9:0d:6c:70:
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0b:29:a2:14:10:21:d1:08:c6:d4:b2:a9:d8:58:ac:
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51:1a:17:19:8f:87:25:b7:f6:4a:da:4a:de:2e:1d:
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62:7c:50:5d:09:4c:0e:98:a9:a3:32:bb:58:5c:6f:
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de:01:f8:43:a6:0c:66:f9:66:20:f8:9d:00:5f:05:
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c5:f0:c8:b1:87:2a:4e:04:39:ab:4a:6b:f6:66:ee:
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f2:82:9b:67:be:2f:c9:93:2a:8b:2f:ab:f6:f2:e1:
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6e:ed
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Exponent: 65537 (0x10001)
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X509v3 extensions:
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X509v3 Subject Key Identifier:
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01:DF:A7:0A:81:85:9F:3F:03:A6:40:BD:4F:A9:E4:93:F3:FE:89:A3
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X509v3 Authority Key Identifier:
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keyid:01:DF:A7:0A:81:85:9F:3F:03:A6:40:BD:4F:A9:E4:93:F3:FE:89:A3
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X509v3 Basic Constraints: critical
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CA:TRUE
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Signature Algorithm: sha256WithRSAEncryption
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3b:83:25:eb:fe:e9:b3:82:bf:bb:7d:49:2e:0d:77:fc:de:44:
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4b:85:f4:82:ac:1c:31:eb:61:46:41:20:ed:5a:05:06:ce:3b:
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58:83:b4:be:15:03:72:c1:13:1e:9f:3a:03:79:7d:bc:6b:a1:
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4b:33:5f:df:fa:3e:dc:4b:7b:ee:54:f2:2e:4c:3b:3b:4a:f8:
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ec:71:3e:bb:43:7e:76:e5:5d:56:fa:21:6e:04:2a:14:e7:59:
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eb:12:ed:1d:96:9c:e5:ad:ce:a4:50:5c:a1:54:be:80:67:dd:
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07:24:2d:5d:68:f5:ea:b3:60:81:3f:6a:86:f8:cf:41:9a:55:
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a9:c0:f4:f4:b3:cd:b5:4f:b1:7e:fd:44:20:f5:07:b3:66:57:
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47:0a:11:0e:c8:ac:2a:e1:2f:b1:25:0d:5f:c6:94:da:ed:55:
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d1:e3:63:49:b0:cf:d8:ae:fb:46:09:bf:1b:dc:1c:34:c4:46:
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2d:74:e9:bd:bc:29:7c:c9:cf:e3:f9:fe:1c:a0:db:0a:91:5f:
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37:48:7d:a5:c0:8d:6d:24:ba:ae:67:c7:22:54:00:bc:31:0f:
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ff:29:cf:be:ee:36:de:30:e9:67:c9:a1:20:cc:e9:7a:c0:22:
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18:75:e4:ad:ed:66:0f:44:cc:19:80:67:fe:43:8c:ad:11:72:
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60:b2:69:7c
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```
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You will also need to configure access to the CF API. To prepare for this, we will now
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use the [cf](https://docs.cloudfoundry.org/cf-cli/install-go-cli.html) command-line tool.
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First, while in the directory containing the `metadata` file you used earlier to authenticate
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to CF, run `$ pcf target`. This points the `cf` tool at the same place as the `pcf` tool. Next,
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run `$ cf api` to view the API endpoint that Vault will use.
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Next, configure a user for Vault to use. This plugin was tested with Org Manager level
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permissions, but lower level permissions _may_ be usable.
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```shell-session
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$ cf create-user vault pa55w0rd
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$ cf orgs
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$ cf org-users my-example-org
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$ cf set-org-role vault my-example-org OrgManager
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```
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Specifically, the `vault` user created here will need to be able to perform the following API calls:
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- Method: "GET", endpoint: "/v2/info"
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- Method: "POST", endpoint: "/oauth/token"
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- Method: "GET", endpoint: "/v2/apps/\$APP_ID"
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- Method: "GET", endpoint: "/v2/organizations/\$ORG_ID"
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- Method: "GET", endpoint: "/v2/spaces/\$SPACE_ID"
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Next, PCF often uses a self-signed certificate for TLS, which can be rejected at first
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with an error like:
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```
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x509: certificate signed by unknown authority
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```
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If you encounter this error, you will need to first gain a copy of the certificate that CF
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is using for the API via:
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```shell-session
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$ openssl s_client -showcerts -servername domain.com -connect domain.com:443
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```
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Here is an example of a real call:
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```shell-session
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$ openssl s_client -showcerts -servername api.sys.somewhere.cf-app.com -connect api.sys.somewhere.cf-app.com:443
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```
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Part of the response will contain a certificate, which you'll need to copy and paste to
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a well-formatted local file. Please see `ca.crt` above for an example of how the certificate
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should look, and how to verify it can be parsed using `openssl`. The walkthrough below presumes
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you name this file `cfapi.crt`.
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### Walkthrough
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After obtaining the information described above, a Vault operator will configure the CF auth method
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like so:
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```shell-session
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$ vault auth enable cf
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$ vault write auth/cf/config \
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identity_ca_certificates=@ca.crt \
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cf_api_addr=https://api.dev.cfdev.sh \
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cf_username=vault \
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cf_password=pa55w0rd \
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cf_api_trusted_certificates=@cfapi.crt
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$ vault write auth/cf/roles/my-role \
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bound_application_ids=2d3e834a-3a25-4591-974c-fa5626d5d0a1 \
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bound_space_ids=3d2eba6b-ef19-44d5-91dd-1975b0db5cc9 \
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bound_organization_ids=34a878d0-c2f9-4521-ba73-a9f664e82c7bf \
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policies=my-policy
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```
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Once configured, from a CF instance containing real values for the `CF_INSTANCE_CERT` and
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`CF_INSTANCE_KEY`, login can be performed using:
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```shell-session
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$ vault login -method=cf role=test-role
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```
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For CF, we do also offer an agent that, once configured, can be used to obtain a Vault token on
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your behalf.
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### Maintenance
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In testing we found that CF instance identity CA certificates were set to expire in 3 years. Some
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CF docs indicate they expire every 4 years. However long they last, at some point you may need
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to add another CA certificate - one that's soon to expire, and one that is currently or soon-to-be
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valid.
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```shell-session
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$ CURRENT=$(cat /path/to/current-ca.crt)
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$ FUTURE=$(cat /path/to/future-ca.crt)
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$ vault write auth/vault-plugin-auth-cf/config identity_ca_certificates="$CURRENT,$FUTURE"
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```
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If Vault receives a `CF_INSTANCE_CERT` matching _any_ of the `identity_ca_certificates`,
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the instance cert will be considered valid.
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A similar approach can be taken to update the `cf_api_trusted_certificates`.
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### Troubleshooting At-A-Glance
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If you receive an error containing `x509: certificate signed by unknown authority`, set
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`cf_api_trusted_certificates` as described above.
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If you're unable to authenticate using the `CF_INSTANCE_CERT`, first obtain a current copy
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of your `CF_INSTANCE_CERT` and copy it to your local environment. Then divide it into two
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files, each being a distinct certificate. The first certificate tends to be the actual
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`identity.crt`, and the second one tends to be the `intermediate.crt`. Verify each are
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properly named and formatted using a command like:
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```shell-session
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$ openssl x509 -in ca.crt -text -noout
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```
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Then, verify that the certificates are properly chained to the `ca.crt` you've configured:
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```shell-session
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$ openssl verify -CAfile ca.crt -untrusted intermediate.crt identity.crt
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```
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This should show a success response. If it doesn't, try to identify the root cause, be it
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an expired certificate, an incorrect `ca.crt`, or a Vault configuration that doesn't
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match the certificates you're checking.
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## API
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The CF auth method has a full HTTP API. Please see the [CF Auth API](/api/auth/cf)
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for more details.
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