Cassandra and Vault - distributed secret store

4 min read
Mar 9, 2018

Hello all, I'm doing a mini-series of blog posts on using Cassandra and Hashicorp Vault. For the first blog in this series, I'll look at using Cassandra as a Datastore for Vault secrets, then how to generate Cassandra secrets using Vault, and I'll also demonstrate how to manage Cassandra credentials from Vault. Attention: This is not intended to be followed straight on for production systems as several key security features are not done properly (ex: Disabling Cassandra superuser). The definition of Vault is:
Vault secures, stores, and tightly controls access to tokens, passwords, certificates, API keys, and other secrets in modern computing. Vault handles leasing, key revocation, key rolling, and auditing. Through a unified API, users can access an encrypted Key/Value store and network encryption-as-a-service, or generate AWS IAM/STS credentials, SQL/NoSQL databases, X.509 certificates, SSH credentials, and more.
There are several ways to deploy Vault. And several storage engines, Cassandra being one of them. Cassandra gives the advantage of a distributed, highly-available, geo-replicated storage. Since we want to manage secrets, this can be an interesting point. From here, I'm going to guide you how to use Cassandra as a Vault datastore.

1. Setup Cassandra

First, we need to setup Cassandra for storing the data. In this guide, I'm using CCM to achieve this. Create a 3.11.1, 3 node cassandra cluster [code language="bash"] $ ccm create triple3111 -v3.11.2 -n 3 -s [/code]
Check if the cluster is running
[code language="bash"] $ ccm status Cluster: 'triple3111' --------------------- node3: UP node2: UP node1: UP $ ccm node1 nodetool status Datacenter: datacenter1 ======================= Status=Up/Down |/ State=Normal/Leaving/Joining/Moving -- Address Load Tokens Owns (effective) Host ID Rack UN 166.89 KiB 1 100.0% 6c160c38-9041-4109-a98f-c9100f0f297a rack1 UN 153.52 KiB 1 100.0% 900c1007-b3e9-402b-8ab1-9f1f093a0720 rack1 UN 174.13 KiB 1 100.0% 5f54cf00-533e-4400-a898-ab2bd3fe8c17 rack1 [/code]
Create the Vault keyspaces (You can find more information here)
[code language="bash"] $ ccm node1 cqlsh -e "CREATE KEYSPACE \"vault\" WITH REPLICATION = {'class': 'NetworkTopologyStrategy','datacenter1': 3};" $ ccm node1 cqlsh -e "CREATE TABLE \"vault\".\"entries\" (bucket text,key text,value blob,PRIMARY KEY (bucket, key)) WITH CLUSTERING ORDER BY (key ASC);" [/code]
Now, we need to enable Authentication and Authorization, for that, we stop the cluster, edit the configs, and start again
[code language="bash"] $ ccm stop $ # Edit cassandra.yaml on the 3 nodes $ ccm start [/code]
Confirm that this is working as expected:
[code language="bash"] $ ccm node1 cqlsh -u cassandra -p cassandra cassandra@cqlsh> list users; name | super -----------+------- cassandra | True [/code]
Everything Cassandra is done at this point! Let's move to Vault!

2. Install and Configure Vault

Now that we have Cassandra set and running, let's get vault working!
Create a directory to install vault, and download vault.
[code language="bash"] $ mkdir vault $ cd vault $ wget "" $ unzip [/code]
Let's test vault:
[code language="bash"] $ ./vault -h Usage: vault <command> [args] Common commands: read Read data and retrieves secrets write Write data, configuration, and secrets delete Delete secrets and configuration list List data or secrets login Authenticate locally server Start a Vault server status Print seal and HA status unwrap Unwrap a wrapped secret Other commands: audit Interact with audit devices auth Interact with auth methods lease Interact with leases operator Perform operator-specific tasks path-help Retrieve API help for paths policy Interact with policies secrets Interact with secrets engines ssh Initiate an SSH session token Interact with tokens [/code]
At this moment, Vault is not yet running, and we just confirmed that the vault binary is in working condition. For this blog, I'm running vault in dev mode (-dev), but since there is a storage engine present, the second time you would start vault with the storage engine and in dev mode, it will fail to start. To avoid this, either TRUNCATE the Cassandra table, or use Vault in non-dev mode.
First, create a vault config file ( documentation), setting Cassandra as the data engine:
[code language="bash"] $ vim config.json storage "cassandra" { hosts = "localhost" consistency = "LOCAL_QUORUM" protocol_version = 3 username = "cassandra" password = "cassandra" } listener "tcp" { address = "" tls_disable = 1 } [/code]
Now let's start vault:
[code language="bash"] $ ./vault server -dev -config config.json ==> Vault server configuration: Cgo: disabled Cluster Address: Listener 1: tcp (addr: "", cluster address: "", tls: "disabled") Listener 2: tcp (addr: "", cluster address: "", tls: "disabled") Log Level: info Mlock: supported: true, enabled: false Redirect Address: Storage: cassandra Version: Vault v0.9.5 Version Sha: 36edb4d42380d89a897e7f633046423240b710d9 WARNING! dev mode is enabled! In this mode, Vault runs entirely in-memory and starts unsealed with a single unseal key. The root token is already authenticated to the CLI, so you can immediately begin using Vault. You may need to set the following environment variable: $ export VAULT_ADDR='' The unseal key and root token are displayed below in case you want to seal/unseal the Vault or re-authenticate. Unseal Key: irNaBhZFlHjbx/2y76/+Hd0u41XxxaE6HbuCGWzc0ME= Root Token: f467dc15-4381-061a-7fe3-2561baaaa6ce Development mode should NOT be used in production installations! ==> Vault server started! Log data will stream in below: [/code] At this point we have vault running. Let's export the variable and insert some secrets [code language="bash"] $ export VAULT_ADDR='' $ vault write secret/hello value=world Success! Data written to: secret/hello [/code]
Now we can check if Cassandra is getting data:
[code language="bash"] $ ccm node1 cqlsh -u cassandra -p cassandra cassandra@cqlsh> SELECT count(*) FROM "vault"."entries"; count ------- 48 [/code]
It is working! In my next blog post, I will demonstrate how to configure and use the Cassandra database engine to generate Cassandra secrets!

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