20.12.2019 | Michal Slovík | comment icon 0 Comment

Setup HashiCorp Vault on Docker

Vault secures, stores, and tightly controls access to tokens, passwords, certificates, API keys, and other secrets in modern computing. Vault is primarily used in production environments to manage secrets. Vault is a complex system that has many different pieces. There is a clear separation of components that are inside or outside of the security barrier. Only the storage backend and the HTTP API are outside, all other components are inside the barrier.

Figure 1: Architecture of Vault and Spring App (Click to enlarge)

The storage backend is untrusted and is used to durably store encrypted data. When the Vault server is started, it must be provided with a storage backend so that data is available across restarts. The HTTP API similarly must be started by the Vault server on start so that clients can interact with it.

Once started, the Vault is in a sealed state. Before any operation can be performed on the Vault it must be unsealed. This is done by providing the unseal keys. When the Vault is initialized it generates an encryption key which is used to protect all the data. That key is protected by a master key. By default, Vault uses a technique known as Shamir’s secret sharing algorithm to split the master key into 5 shares, any 3 of which are required to reconstruct the master key

All examples in this article are for development and study purposes only, please DO NOT use them in production.

How to install vault on the machine

Installing the vault is very simple. Download latest available image on vault page, find the appropriate package for your system and download it. Vault is packaged as a zip archive.

After downloading Vault, we unzip the package. Vault runs as a single binary named vault. Any other files in the package can be safely removed and Vault will still function.

The final step is to make sure that the vault binary is available on the PATH.

We can verify our installation via this command:

Run the vault locally

Run vault ‘dev’ mode on local machine

Firstly we can start Vault as a server in “dev” mode like so: vault server -dev. This dev-mode server requires no further setup, and our local vault CLI will be authenticated to talk to it. This makes it easy to experiment with Vault or start a Vault instance for development. Every feature of Vault is available in “dev” mode.

Never use “dev” mode server in production. It is unsecured and will lose data on every restart since it stores data in-memory)

Start the vault. You should see output similar:

With the dev server running, do the following three things. Launch a new terminal session, where we export vault address: export VAULT_ADDR='http://127.0.0.1:8200'

On Windows you must use command set instead export.

or if we want to use secure version export VAULT_ADDR='https://127.0.0.1:8201'.

We save the unseal key and root token copy and export too: export VAULT_DEV_ROOT_TOKEN_ID="s.E1qGaBVCSsykjjr4HttLa9E1"

Verify the server is running by running the vault status command.

Run vault server on the local machine

We should have installed vault on your local machine, without any running instance of the vault. If we would like to start vault server we need to have the configuration file. Vault is configured using HCL files. The configuration file for Vault is relatively simple:

Then we are able to run command to start vault server:

vault server -config vault-config.hcl

Initialization is the process configuring the Vault. This only happens once when the server is started against a new backend that has never been used with Vault before. During initialization, the encryption keys are generated, unseal keys are created, and the initial root token is setup. To initialize Vault use vault operator init. This is an unauthenticated request, but it only works on brand new Vaults with no data. Initialization outputs two incredibly important pieces of information: the unseal keys and the initial root token. This is the only time ever that all of this data is known by Vault, and also the only time that the unseal keys should ever be so close together. Don’t forget these keys!

Every initialized Vault server starts in the sealed state. From the configuration, Vault can access the physical storage, but it can’t read any of it because it doesn’t know how to decrypt it. The process of teaching Vault how to decrypt the data is known as unsealing the Vault.

If we lost these keys or get some errors during the process we must start again. Stop any running instance of the Vault. Delete whole files created by Vault ( vault-volume/core/, vault-volume/sys/, …) and start again.

If we would like to unseal vault we must input three times any of 5 unseal keys:

After each command, we should see increasing Unseal Progress 1/3. After that we can check vault status and we should see Sealed false.

With the root token, we are able to log in like root vault login s.KkNJYWF5g0pomcCLEmDdOVCW.

and we can reseal the Vault with vault operator seal.

Run vault on docker

Run vault ‘dev’ on docker and use with Spring

Our prerequisites are to have installed and running docker (with docker-compose). The vault has the official repository on docker hub.

If we would like to start vault on docker without any other file:

In our case we create docker-compose.dev.yml file, where we configured all necessary parameters for configurations:

For development purpose, we use very easy token 00000000-0000-0000-0000-000000000000.

Before we tried this command we should see, that we use certificate.pem and key.pem which were generated to have secured SSL communication between the running vault and other application, like Spring. These certificates were generated by openssl.

Finally, before you start this service, we need to have that certificate on that volume.

In project root folder we run following commands:

We can run whole docker file with this command:

docker-compose -f docker-compose.dev.yml up --build -d

Run vault server on docker

Our requirements are very similar to the previous case. In this scenario, we use docker-compose.server.yml file where are some changes. We moved the initial script to a separate file because the vault generates keys during startup and these keys are required for further configuration.

This workflow-vault script is placed on vault-volume with certificates. We also need this configuration file from the previous step, vault-test.hcl where is defined where are placed the certificates and keys.

And we use spring-policy.hcl the file which is used for policy.

And the bash script workflow-vault.sh:

Then we can add this generated token to Spring Application and use it.

Use Vault with Spring Boot Application

With Spring Cloud Vault we can access our secrets inside Vault. Secrets are picked up at startup of our application. Spring Cloud Vault uses the data from your application (application name, active contexts) to determine contexts paths in which you stored your secrets. First, we add to our pom file this dependency:

The current version of Spring Vault requires Spring Framework in version 4.3.7.RELEASE or better.

After that, we create Configuration class, where we defined our token to the vault, and where can find our vault instance (“vault” represent name from docker container, running on port 8201 which is exported to the world via https)

After that we create Credential Service class, where we are able to create, read and delete our credentials or secrets:

We use kv for storing our credentials, because is easy to reach them via Rest services, but before start Spring application we must say to vault that kv is enabled vault secrets enable -version=1 kv

And if we work with the Spring Boot certificate, we also need to know where the vault certificates are stored, so we have to tell them where they are:

All the above commands are stored into the script which is running in docker-compose along with vault service.

Check communication with Postman

If we have run the Vault and Spring application correctly, we can use any browser or postman application to verify. The Vault is can be accessed on https://localhost:8201 and Spring application using swagger https://localhost:8444/swagger-ui.html#/ where you can perform multiple rest services, such as adding, retrieving, or deleting credentials.

Figure 2: Sequence diagram of Vault and Spring Boot Application (Click to enlarge)

Conclusion

Our entire code is available at EXXETA gitlab. You can easily edit it and give us feedback. We hope this tutorial has provided you with new information about the Vault and how to use it with Spring Framework.

Sources

Docker-compose HashiCorp OpenSSL Security Vault

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