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Using the new transit logic requires slightly different configuration. additionally there is some backwards compatibility support, which also needed documentation. The existing description of how to configure hashicorp vault to work with ceph was also incomplete. I've fleshed that out a bit, including considerably more information on how to use configure and use the vault secret agent with ceph. Fixes: http://tracker.ceph.com/issues/48746 Signed-off-by: Marcus Watts <mwatts@redhat.com>
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470 lines
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ReStructuredText
===========================
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HashiCorp Vault Integration
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===========================
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HashiCorp `Vault`_ can be used as a secure key management service for
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`Server-Side Encryption`_ (SSE-KMS).
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.. ditaa::
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+---------+ +---------+ +-------+ +-------+
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| Client | | RadosGW | | Vault | | OSD |
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+---------+ +---------+ +-------+ +-------+
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| create secret | | |
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| key for key ID | | |
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|-----------------+---------------->| |
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| | | |
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| upload object | | |
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| with key ID | | |
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|---------------->| request secret | |
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| | key for key ID | |
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| |---------------->| |
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| |<----------------| |
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| | return secret | |
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| | key | |
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| | | |
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| | encrypt object | |
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| | with secret key | |
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| |--------------+ | |
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| | | | |
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| |<-------------+ | |
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| | | |
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| | store encrypted | |
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| | object | |
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| |------------------------------>|
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#. `Vault secrets engines`_
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#. `Vault authentication`_
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#. `Vault namespaces`_
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#. `Create a key in Vault`_
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#. `Configure the Ceph Object Gateway`_
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#. `Upload object`_
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Some examples below use the Vault command line utility to interact with
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Vault. You may need to set the following environment variable with the correct
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address of your Vault server to use this utility::
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export VAULT_ADDR='https://vault-server-fqdn:8200'
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Vault secrets engines
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=====================
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Vault provides several secrets engines, which can store, generate, and encrypt
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data. Currently, the Object Gateway supports:
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- `KV secrets engine`_ version 2
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- `Transit engine`_
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KV secrets engine
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-----------------
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The KV secrets engine is used to store arbitrary key/value secrets in Vault. To
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enable the KV engine version 2 in Vault, use the following command::
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vault secrets enable -path secret kv-v2
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The Object Gateway can be configured to use the KV engine version 2 with the
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following setting::
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rgw crypt vault secret engine = kv
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Transit secrets engine
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----------------------
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The transit engine handles cryptographic functions on data in-transit. To enable
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it in Vault, use the following command::
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vault secrets enable transit
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The Object Gateway can be configured to use the transit engine with the
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following setting::
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rgw crypt vault secret engine = transit
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Vault authentication
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====================
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Vault supports several authentication mechanisms. Currently, the Object
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Gateway can be configured to authenticate to Vault using the
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`Token authentication method`_ or a `Vault agent`_.
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Most tokens in Vault have limited lifetimes and powers. The only
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sort of Vault token that does not have a lifetime are root tokens.
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For all other tokens, it is necesary to periodically refresh them,
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either by performing initial authentication, or by renewing the token.
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Ceph does not have any logic to perform either operation.
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The simplest best way to use Vault tokens with ceph is to
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also run the Vault agent and have it refresh the token file.
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When the Vault agent is used in this mode, file system permissions
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can be used to restrict who has the use of tokens.
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Instead of having Vault agent refresh a token file, it can be told
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to act as a proxy server. In this mode, Vault will add a token when
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necessary and add it to requests passed to it before forwarding them on
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to the real server. Vault agent will still handle token renewal just
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as it would when storing a token in the filesystem. In this mode, it
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is necessary to properly secure the network path rgw uses to reach the
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Vault agent, such as having the Vault agent listen only to localhost.
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Token policies for the object gateway
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-------------------------------------
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All Vault tokens have powers as specified by the polices attached
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to that token. Multiple policies may be associated with one
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token. You should only use the policy necessary for your
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configuration.
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When using the kv secret engine with the object gateway::
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vault policy write rgw-kv-policy -<<EOF
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path "secret/data/*" {
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capabilities = ["read"]
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}
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EOF
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When using the transit secret engine with the object gateway::
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vault policy write rgw-transit-policy -<<EOF
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path "transit/keys/*" {
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capabilities = [ "create", "update" ]
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denied_parameters = {"exportable" = [], "allow_plaintext_backup" = [] }
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}
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path "transit/keys/*" {
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capabilities = ["read", "delete"]
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}
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path "transit/keys/" {
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capabilities = ["list"]
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}
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path "transit/keys/+/rotate" {
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capabilities = [ "update" ]
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}
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path "transit/*" {
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capabilities = [ "update" ]
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}
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EOF
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If you had previously used an older version of ceph with the
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transit secret engine, you might need the following policy::
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vault policy write old-rgw-transit-policy -<<EOF
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path "transit/export/encryption-key/*" {
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capabilities = ["read"]
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}
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EOF
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Token authentication
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--------------------
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.. note: Never use root tokens with ceph in production environments.
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The token authentication method expects a Vault token to be present in a
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plaintext file. The Object Gateway can be configured to use token authentication
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with the following settings::
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rgw crypt vault auth = token
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rgw crypt vault token file = /run/.rgw-vault-token
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rgw crypt vault addr = https://vault-server-fqdn:8200
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Adjust these settinsg to match your configuration.
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For security reasons, the token file must be readable by the Object Gateway
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only.
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You might set up vault agent as follows::
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vault write auth/approle/role/rgw-ap \
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token_policies=rgw-transit-policy,default \
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token_max_ttl=60m
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Change the policy here to match your configuration.
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Get the role-id::
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vault read auth/approle/role/rgw-ap/role-id -format=json | \
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jq -r .data.role_id
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Store the output in some file, such as /usr/local/etc/vault/.rgw-ap-role-id
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Get the secret-id::
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vault read auth/approle/role/rgw-ap/role-id -format=json | \
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jq -r .data.role_id
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Store the output in some file, such as /usr/local/etc/vault/.rgw-ap-secret-id
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Create configuration for the Vault agent, such as::
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pid_file = "/run/rgw-vault-agent-pid"
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auto_auth {
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method "AppRole" {
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mount_path = "auth/approle"
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config = {
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role_id_file_path ="/usr/local/etc/vault/.rgw-ap-role-id"
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secret_id_file_path ="/usr/local/etc/vault/.rgw-ap-secret-id"
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remove_secret_id_file_after_reading ="false"
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}
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}
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sink "file" {
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config = {
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path = "/run/.rgw-vault-token"
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}
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}
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}
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vault {
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address = "https://vault-server-fqdn:8200"
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}
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Then use systemctl or another method of your choice to run
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a persistent daemon with the following arguments::
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/usr/local/bin/vault agent -config=/usr/local/etc/vault/rgw-agent.hcl
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Once the vault agent is running, the token file should be populated
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with a valid token.
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Vault agent
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-----------
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The Vault agent is a client daemon that provides authentication to Vault and
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manages token renewal and caching. It typically runs on the same host as the
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Object Gateway. With a Vault agent, it is possible to use other Vault
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authentication mechanism such as AppRole, AWS, Certs, JWT, and Azure.
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The Object Gateway can be configured to use a Vault agent with the following
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settings::
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rgw crypt vault auth = agent
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rgw crypt vault addr = http://127.0.0.1:8100
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You might set up vault agent as follows::
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vault write auth/approle/role/rgw-ap \
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token_policies=rgw-transit-policy,default \
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token_max_ttl=60m
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Change the policy here to match your configuration.
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Get the role-id:
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vault read auth/approle/role/rgw-ap/role-id -format=json | \
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jq -r .data.role_id
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Store the output in some file, such as /usr/local/etc/vault/.rgw-ap-role-id
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Get the secret-id:
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vault read auth/approle/role/rgw-ap/role-id -format=json | \
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jq -r .data.role_id
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Store the output in some file, such as /usr/local/etc/vault/.rgw-ap-secret-id
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Create configuration for the Vault agent, such as::
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pid_file = "/run/rgw-vault-agent-pid"
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auto_auth {
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method "AppRole" {
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mount_path = "auth/approle"
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config = {
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role_id_file_path ="/usr/local/etc/vault/.rgw-ap-role-id"
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secret_id_file_path ="/usr/local/etc/vault/.rgw-ap-secret-id"
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remove_secret_id_file_after_reading ="false"
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}
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}
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}
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cache {
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use_auto_auth_token = true
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}
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listener "tcp" {
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address = "127.0.0.1:8100"
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tls_disable = true
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}
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vault {
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address = "https://vault-server-fqdn:8200"
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}
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Then use systemctl or another method of your choice to run
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a persistent daemon with the following arguments::
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/usr/local/bin/vault agent -config=/usr/local/etc/vault/rgw-agent.hcl
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Once the vault agent is running, you should find it listening
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to port 8100 on localhost, and you should be able to interact
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with it using the vault command.
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Vault namespaces
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================
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In the Enterprise version, Vault supports the concept of `namespaces`_, which
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allows centralized management for teams within an organization while ensuring
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that those teams operate within isolated environments known as tenants.
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The Object Gateway can be configured to access Vault within a particular
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namespace using the following configuration setting::
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rgw crypt vault namespace = tenant1
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Create a key in Vault
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=====================
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.. note:: Keys for server-side encryption must be 256-bit long and base-64
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encoded.
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Using the KV engine
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-------------------
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A key for server-side encryption can be created in the KV version 2 engine using
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the command line utility, as in the following example::
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vault kv put secret/myproject/mybucketkey key=$(openssl rand -base64 32)
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Sample output::
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====== Metadata ======
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Key Value
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--- -----
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created_time 2019-08-29T17:01:09.095824999Z
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deletion_time n/a
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destroyed false
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version 1
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Note that in the KV secrets engine, secrets are stored as key-value pairs, and
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the Gateway expects the key name to be ``key``, i.e. the secret must be in the
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form ``key=<secret key>``.
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Using the Transit engine
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------------------------
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Keys created for use with the Transit engine should no longer be marked
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exportable. They can be created with::
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vault write -f transit/keys/mybucketkey
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The command above creates a keyring, which contains a key of type
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``aes256-gcm96`` by default. To verify that the key was correctly created, use
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the following command::
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vault read transit/mybucketkey
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Sample output::
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Key Value
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--- -----
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derived false
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exportable false
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name mybucketkey
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type aes256-gcm96
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Configure the Ceph Object Gateway
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=================================
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Edit the Ceph configuration file to enable Vault as a KMS backend for
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server-side encryption::
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rgw crypt s3 kms backend = vault
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Choose the Vault authentication method, e.g.::
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rgw crypt vault auth = token
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rgw crypt vault token file = /run/.rgw-vault-token
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rgw crypt vault addr = https://vault-server-fqdn:8200
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Or::
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rgw crypt vault auth = agent
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rgw crypt vault addr = http://localhost:8100
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Choose the secrets engine::
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rgw crypt vault secret engine = kv
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Or::
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rgw crypt vault secret engine = transit
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Optionally, set the Vault namespace where encryption keys will be fetched from::
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rgw crypt vault namespace = tenant1
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Finally, the URLs where the Gateway will retrieve encryption keys from Vault can
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be restricted by setting a path prefix. For instance, the Gateway can be
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restricted to fetch KV keys as follows::
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rgw crypt vault prefix = /v1/secret/data
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Or, when using the transit secret engine::
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rgw crypt vault prefix = /v1/transit
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In the example above, the Gateway would only fetch transit encryption keys under
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``https://vault-server:8200/v1/transit``.
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Transit engine compatibility support
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------------------------------------
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The transit engine has compatibility support for previous
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versions of ceph, which used the transit engine as a simple key store.
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There is a a "compat" option which can be given to the transit
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engine to configure the compatibility support,
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To entirely disable backwards support, use::
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rgw crypt vault secret engine = transit compat=0
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This will be the default in future verisons. and is safe to use
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for new installs using the current version.
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This is the normal default with the current version::
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rgw crypt vault secret engine = transit compat=1
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This enables the new engine for newly created objects,
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but still allows the old engine to be used for old objects.
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In order to access old and new objects, the vault token given
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to ceph must have both the old and new transit policies.
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To force use of only the old engine, use::
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rgw crypt vault secret engine = transit compat=2
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This mode is automatically selected if the vault prefix
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ends in export/encryption-key, which was the previously
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documented setting.
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Upload object
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=============
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When uploading an object to the Gateway, provide the SSE key ID in the request.
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As an example, for the kv engine, using the AWS command-line client::
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aws --endpoint=http://radosgw:8000 s3 cp plaintext.txt s3://mybucket/encrypted.txt --sse=aws:kms --sse-kms-key-id myproject/mybucketkey
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As an example, for the transit engine (new flavor), using the AWS command-line client::
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aws --endpoint=http://radosgw:8000 s3 cp plaintext.txt s3://mybucket/encrypted.txt --sse=aws:kms --sse-kms-key-id mybucketkey
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The Object Gateway will fetch the key from Vault, encrypt the object and store
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it in the bucket. Any request to download the object will make the Gateway
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automatically retrieve the correspondent key from Vault and decrypt the object.
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Note that the secret will be fetched from Vault using a URL constructed by
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concatenating the base address (``rgw crypt vault addr``), the (optional)
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URL prefix (``rgw crypt vault prefix``), and finally the key ID.
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In the kv engine example above, the Gateway would fetch the secret from::
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http://vaultserver:8200/v1/secret/data/myproject/mybucketkey
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In the transit engine example above, the Gateway would encrypt the secret using this key::
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http://vaultserver:8200/v1/transit/mybucketkey
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.. _Server-Side Encryption: ../encryption
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.. _Vault: https://www.vaultproject.io/docs/
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.. _Token authentication method: https://www.vaultproject.io/docs/auth/token.html
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.. _Vault agent: https://www.vaultproject.io/docs/agent/index.html
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.. _KV Secrets engine: https://www.vaultproject.io/docs/secrets/kv/
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.. _Transit engine: https://www.vaultproject.io/docs/secrets/transit
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.. _namespaces: https://www.vaultproject.io/docs/enterprise/namespaces/index.html
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