Merge pull request '1-add-zabbix-example-with-template-strings' (#2) from 1-add-zabbix-example-with-template-strings into master

Reviewed-on: #2

README.md

@@ -19,7 +19,7 @@ Refer to [config/vault.hcl](config/vault.hcl) for content.
 ## Configure
 
 Once Vault's initialized and with your `root` token in hand log in via the `token` auth method, make the following changes:
-* Add policies from [policies/role-administrator](policies/role-administrator) subdirectory into Vault
+* Add policies from [policies/administrator](policies/administrator) subdirectory into Vault
 * Create group `administrators`
 * Assign policies `administrator` and `auditor` to that group
 * Create one entity to represent yourself as an administrator
@@ -60,7 +60,7 @@ Get the Vault command-line client via [vaultproject.io/downloads](https://www.va
     ----     ----    -----------
     file/    file    n/a
     ```
-* We're going to allow all human users to change their own `userpass` password. The policy to do so is at [policies/role-human/change-own-password.hcl](policies/role-human/change-own-password.hcl). For a hands-on example of an actual password change via HTTP API see [Hands-on](#hands-on) but first:
+* We're going to allow all human users to change their own `userpass` password. The policy to do so is at [policies/human/change-own-password.hcl](policies/human/change-own-password.hcl). For a hands-on example of an actual password change via HTTP API see [Hands-on](#hands-on) but first:
 
     * Before you can load the policy into Vault you need to replace the string `ACCESSOR` in it with _your_ particular `userpass` accessor. Get it like so:
         ```
@@ -73,7 +73,7 @@ Get the Vault command-line client via [vaultproject.io/downloads](https://www.va
         token/       token       auth_token_d3aad127       token based credentials
         userpass/    userpass    auth_userpass_6671d643    n/a
         ```
-        Over in [policies/role-human/change-own-password.hcl](policies/role-human/change-own-password.hcl) replace `ACCESSOR` with what you're seeing here in the Accessor column. Feel free to read up on [templated policies](https://www.vaultproject.io/docs/concepts/policies#templated-policies) for more info.
+        Over in [policies/human/change-own-password.hcl](policies/human/change-own-password.hcl) replace `ACCESSOR` with what you're seeing here in the Accessor column. Feel free to read up on [templated policies](https://www.vaultproject.io/docs/concepts/policies#templated-policies) for more info.
 
     * Load the policy
     * Create a group for humans and assign the policy `change-own-password` to it.
@@ -94,18 +94,83 @@ Get the Vault command-line client via [vaultproject.io/downloads](https://www.va
         ```
         Entity IDs are coming from `vault list identity/entity/id` and/or `vault read identity/entity/name/<name>`.
 
-* Optionally [policies/role-cfgmgmt/cfgmgmt.hcl](policies/role-cfgmgmt/cfgmgmt.hcl) gets you started with read-only secrets access for example for a config management tool like Ansible.
+* Optionally [policies/cfgmgmt/cfgmgmt.hcl](policies/cfgmgmt/cfgmgmt.hcl) gets you started with read-only secrets access for example for a config management tool like Ansible.
 
-    You'll want to create an Ansible entity with an alias, create both a `token` and a `userpass` alias and use the latter one to authenticate against Vault to retrieve a token. You'll likely want a distinct group where your Ansible entity becomes a member and which uses a policy such as the example at [policies/role-cfgmgmt/cfgmgmt.hcl](policies/role-cfgmgmt/cfgmgmt.hcl).
+    You'll want to create an Ansible entity and a `userpass` alias. Think of the alias as glue that ties an auth method to an entity. This in turn allows you to specify policy that applies to the entity, gets inherited by aliases and lastly inherited by auth methods.
+
+    In this simple use case create create a user in the `userpass` auth method, use the same name used from both the entity and its alias. Use that user to authenticate against Vault and retrieve a token. You'll likely want a distinct group where your Ansible entity becomes a member and which uses a policy such as the example at [policies/cfgmgmt/cfgmgmt.hcl](policies/cfgmgmt/cfgmgmt.hcl).
 
     From here on out it's just more of what you already did, feel free to make this fit your own approach.
 
-* Optionally from [policies/role-kv-writer/kv-writer.hcl](policies/role-kv-writer/kv-writer.hcl) load a policy that allows affected entities to create `kv` secrets, create new versions for existing secrets and to traverse the UI directory structure of secrets. Entities with this policy will not be able to read secrets nor see if versions exist at a given location.
+* Optionally from [policies/kv-writer/kv-writer.hcl](policies/kv-writer/kv-writer.hcl) load a policy that allows affected entities to create `kv` secrets, create new versions for existing secrets and to traverse the UI directory structure of secrets. Entities with this policy will not be able to read secrets nor see if versions exist at a given location.
 
     Permission to also read/view secrets is commented out in the policy file in case you do need this feature.
 
     Assign the policy to a group as needed.
 
+* As a similar narrowly scoped use case consider a Zabbix monitoring instance that may need access to credentials, session IDs, tokens or other forms of authentication to monitor machines and services.
+
+    Here's one suggestion to set up the basics for Zabbix.
+
+    In Vault with a user that has sufficient permissions:
+    * Create an entity `zabbix` without a policy.
+    * Add an alias of type `userpass` to the entity.
+    * Within the `userpass` auth method create a user (an account if you will) with the same name as the alias you just created so in this case `zabbix`, set a password for the account
+
+    Now tie it all together by creating a group named `rbacgroup_zabbix`. Add the `zabbix` entity to it and make it use the policy `zabbix`. At this point the policy does not yet exist which is fine, you can set a policy name and Vault will offer to `Add new policy`, see screenshot below. Don't worry, this will not actually add a new policy - empty, broken or otherwise. Vault will simply link your group to the policy `zabbix` which does not exist. You'll get to that in a minute.
+
+    Like so:
+    ![Vault 1.11.3 Create Group menu](https://i.imgur.com/3Ni53BE.png)
+
+    Next up check out [policies/zabbix/zabbix.hcl](policies/zabbix/zabbix.hcl). Do some light replacement before importing it into Vault. The policy file contains a few occurrences of the string `GROUPID`, replace them with the group ID of `rbacgroup_zabbix`.
+    * Via Vault's UI you can get the group ID at `Access > Groups > rbacgroup_zabbix`.
+    * Via the `vault` command-line client you can do it like so where the `id` value is what you're after:
+        ```
+        # Get 'rbacgroup_zabbix' group metadata
+        vault kv get /identity/group/name/rbacgroup_zabbix
+
+        # Expected output similar to:
+        == Metadata ==
+
+        ========== Data ==========
+        Key                  Value
+        ---                  -----
+        alias                map[]
+        creation_time        2022-09-22T21:47:57.720309362Z
+        id                   88560da7-e180-3d2e-9053-dc0ee4ba7fbe
+        ...
+        ```
+    With your ID in hand and [policies/zabbix/zabbix.hcl](policies/zabbix/zabbix.hcl) updated import it as a new policy. You're going to want to save it with the same policy name you assigned earlier to `rbacgroup_zabbix` which was `zabbix`. This role will grant read-only access to secrets underneath a folder `for_rbacgroup_zabbix` which in our example lives inside a `kv` version 2 secrets engine mounted at its default location `kv`.
+
+    Now whenever your Zabbix instance needs access to something store secrets underneath `kv/for_rbacgroup_zabbix`. The policy will make sure only the group with correct ID will have access to secrets underneath that directory.
+
+    Log in to Vault with `userpass` and the `zabbix` account from above, get the account's token and lastly double-check that `zabbix` with its token can read a secret:
+    ```
+    curl --silent --location --header 'X-Vault-Token: <token>' \
+        'https://f.q.d.n/v1/kv/data/for_rbacgroup_zabbix/some/secret' \
+        | jq '.data.data'
+    ```
+
+    Configure Zabbix with its own Vault token and enjoy no longer having to store any secrets in Zabbix itself.
+
+    Side note, if your token regularly expires you may want to store the token itself in Vault and let Zabbix monitor token expiry via the Zabbix equivalent of:
+    ```
+    # Look up a token's own attributes
+    curl --silent --location --header 'X-Vault-Token: <token>' \
+        'https://f.q.d.n/v1/auth/token/lookup-self' \
+        | jq '.data.ttl'
+
+    # .data.ttl will show remaining validity in secs:
+    2754536
+    ```
+
+    Users wishing to browse the `rbacgroup_zabbix` directory structure via Vault's UI will need to manually begin their browsing at `kv/list/for_rbacgroup_zabbix`. Users with higher privileges such as administrators will be able to list all directories underneath the root `kv` object in Vault's web UI. This will include not only `zabbix`-specific data but also directories intended for other users which is why `kv/list` access is not granted to `rbacgroup_zabbix`.
+
+    Their `list` permission only begins one lever deeper at `kv/list/for_rbacgroup_zabbix`. It may make sense to communicate an entrypoint link to end users that - in this case - will look like:
+    ```
+    https://f.q.d.n/ui/vault/secrets/kv/list/for_rbacgroup_zabbix
+    ```
+
 ## Clean-up
 
 If during any of the above steps you've used the Vault command-line client to authenticate against Vault with your `root` token make sure that client's `~/.vault-token` file is deleted. It contains the verbatim `root` token.

policies/zabbix/zabbix.hcl

@@ -0,0 +1,12 @@
+# Allow listing secret parent-child connections (as in UI hierarchy). Subdir
+# underneath 'kv' secrets engine will remain hidden though, user has to
+# manually open up
+# ${VAULT_ADDR}/ui/vault/secrets/kv/list/for_{{identity.groups.ids.GROUPID.name}}
+path "kv/metadata/for_{{identity.groups.ids.GROUPID.name}}/*" {
+    capabilities = ["list"]
+}
+
+# Grant read-only access to secrets
+path "kv/data/for_{{identity.groups.ids.GROUPID.name}}/*" {
+    capabilities = ["read"]
+}