Vault Java Driver

A zero-dependency Java client for the Vault secrets management solution from HashiCorp.

This driver strives to implement Vault's full HTTP API, along with supporting functionality such as automatic retry handling. It does so without relying on any other external libraries beyond the Java standard library, and is compatible with Java 7 and up. So it will play nice with all of your projects, greenfield and legacy alike, without causing conflicts with any other dependency.

Installing the Driver

The driver is available from Maven Central, for all modern Java build systems.

Gradle:

dependencies {
    compile('com.bettercloud:vault-java-driver:1.2.0')
}

Maven:

<dependency>
    <groupId>com.bettercloud</groupId>
    <artifactId>vault-java-driver</artifactId>
    <version>1.2.0</version>
</dependency>

Initializing a Driver Instance

The com.bettercloud.vault.VaultConfig class is used to initialize a driver instance with desired settings. In the most basic use cases, where you are only supplying a Vault server address and perhaps a root token, there are convenience constructor methods available:

final VaultConfig config = new VaultConfig("http://127.0.0.1:8200", "3c9fd6be-7bc2-9d1f-6fb3-cd746c0fc4e8");

// You may choose not to provide a root token initially, if you plan to use
// the Vault driver to retrieve one programmatically from an auth backend.
final VaultConfig config = new VaultConfig("http://127.0.0.1:8200");

To explicitly set additional config parameters (*), you can use a builder pattern style to construct the VaultConfig instance. Either way, the initialization process will try to populate any unset values by looking to environment variables.

final VaultConfig config =
    new VaultConfig().
        .address("http://127.0.0.1:8200")               // Defaults to "VAULT_ADDR" environment variable
        .token("3c9fd6be-7bc2-9d1f-6fb3-cd746c0fc4e8")  // Defaults to "VAULT_TOKEN" environment variable
        .openTimeout(5)                                 // Defaults to "VAULT_OPEN_TIMEOUT" environment variable
        .readTimeout(30)                                // Defaults to "VAULT_READ_TIMEOUT" environment variable
        .sslPemFile("/path/on/disk.pem")                // Defaults to "VAULT_SSL_CERT" environment variable
                                                        //    See also: "sslPemUTF8()" and "sslPemResource()"
        .sslVerify(false)                               // Defaults to "VAULT_SSL_VERIFY" environment variable
        .build();

NOTES ON SSL CONFIG

If your Vault server uses a SSL certificate, there are three different options for supplying that certificate to the Vault driver:

sslPemFile(path) - Supply the path to an X.509 certificate in unencrypted PEM format, using UTF-8 encoding.

sslPemResource(path) - Same as above, but the path references a classpath resource rather than a filesystem path (e.g. if you've bundled the PEM file into your applications's JAR, WAR, or EAR file).

sslPemUTF8(contents) - The string contents extracted from the PEM file. For Java to parse the certificate properly, there must be a line-break in between the certificate header and body (see the VaultConfig Javadocs for more detail).

If none of these three methods are called, then VaultConfig will by default check for a VAULT_SSL_CERT environment variable, and if that's set then it will be treated as a filesystem path.

To disable SSL certificate verification altogether, set sslVerify(false). YOU SHOULD NOT DO THIS IS A REAL PRODUCTION SETTING! However, it can be useful in a development or testing server context.

Once you have initialized a VaultConfig object, you can use it to construct an instance of the Vault primary driver class:

final Vault vault = new Vault(config);

Using the Driver

Like the VaultConfig class, Vault too supports a builder pattern DSL style:

final Map<String, String> secrets = new HashMap<String, String>();
secrets.put("value", "world");
secrets.put("other_value", "You can store multiple name/value pairs under a single key");

// Write operation
final LogicalResponse writeResponse = vault.logical()
                                        .write("secret/hello", secrets);

...

// Read operation
final String value = vault.logical()
                       .read("secret/hello")
                       .getData().get("value");

Vault has a number of methods for accessing the classes that implement the various endpoints of Vault's HTTP API:

• logical(): Contains core operations such as reading and writing secrets.
• auth(): Exposes methods for working with Vault's various auth backends (e.g. to programmatically retrieve a token by authenticating with a username and password).
• pki(): Operations on the PKI backend (e.g. create and delete roles, issue certificate credentials).

The driver DSL also allows you to specify retry logic, by chaining the withRetries() ahead of accessing the endpoint implementation:

// Retry up to 5 times if failures occur, waiting 1000 milliseconds in between each retry attempt.
final LogicalResponse response = vault.withRetries(5, 1000)
                                   .logical()
                                   .read("secret/hello");

Reference

Full Javadoc documentation.

Version History

Note that changes to the major version (i.e. the first number) represent possible breaking changes, and may require modifications in your code to migrate. Changes to the minor version (i.e. the second number) should represent non-breaking changes. The third number represents any very minor bugfix patches.

• 1.2.0: This is a substantial release, with numerous additions. It's a minor version number only because there should be no breaking changes. The changes include the following:
  • Switches from Vault 0.5.x to 0.6.x for automated tests.
  • Adds a field to VaultException for capturing the HTTP response code (if any) from Vault.
  • Updates the Gradle build, so that you no longer need empty placeholder values for certain variables elsewhere in your environment.
  • Updates integration test suite to account for breaking changes in Vault 0.6.x (e.g. you can no longer use a token that was obtained from one of the authentication backends to perform tasks such as creating and deleting roles, etc).
  • Deprecates the App ID authentication backend, and adds a new version of the Userpass authentication backend that doesn't require a path prefix. Adds support for the GitHub authentication backend.
  • If the VAULT_TOKEN environment parameter is not set, then the driver will now check for a file named .vault-token in the executing user's home directory, and try to read a token value from that.
  • Deprecates the com.bettercloud.vault.api.Sys class, moving the debug-related methods into their own specific com.bettercloud.vault.api.Debug class instead.
  • Implements some of the lease related endpoints (i.e. revoke, revoke-prefix, revoke-force).
• 1.1.1: Changes the ttl argument to Pki.issue() from Integer to String, to fix a bug preventing you from specifying the time suffix (e.g. "1h").
• 1.1.0: Switches from Vault 0.4.x to 0.5.x for automated tests. Adds support to the Logical API wrapper for listing and deleting secrets. Implements the /v1/sys/health health-check HTTP API endpoint. Implements portions of the PKI backend (e.g. creating and deleting roles, issuing credentials). Marks numerous methods as deprecated, to be removed in a future major release.
• 1.0.0: Drops support for Java 6. Removes all methods marked as @Deprecated in version 0.5.0. Adds support for response metadata (i.e. "lease_id", "renewable", "lease_duration") to all response types, rather than just AuthResponse. Changes leaseDuration type from int to Long in AuthResponse. Removes final declarations on all classes (outside of the JSON package). Various bugfixes. Adds support for auth token self-renewal. Adds support for writing values that return content.
• 0.5.0: Adds support for supplying SSL certificates, and for toggling whether or not the Vault server's SSL certificate will be verified. Also adds support for "openTimeout" and "readTimeout" settings. Deprecates the "timeout", "sslTimeout", "proxyAddress", "proxyPort", "proxyUsername", and "proxyPassword" settings (the proxy settings may return in a future version, but it's too misleading to have methods exposed for settings that won't really be supported soon).
• 0.3.0: Initial public release. Support for writing and reading secrets, authenticating with the "AppID" or "Username & Password" auth backends. All over-the-wire methods support automatic retry logic.

Development

Pull requests are welcomed for bugfixes or enhancements that do not alter the external facing class and method signatures. For any breaking changes that would alter the contract provided by this driver, please open up an issue to discuss it first.

All code changes should include unit test and/or integration test coverage as appropriate. Unit tests are any that can be run in isolation, with no external dependencies. Integration tests are those which require a Vault server instance (at least a Dev Server) up and running.

Unit tests are located under the src/test directory, and can be run with the Grade unitTest task.

Integration tests are located under the src/test-integration directory, and can be run with the Gradle integrationTest task. See the additional README.md file in this directory for more detailed information on the Vault server setup steps required to run the integration test suite.

License

The MIT License (MIT)

Copyright (c) 2016 BetterCloud

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Other Notes

The Vault server system itself is a product of HashiCorp, a completely separate organization.

This client driver adapts JSON parsing code from Ralf Sternberg's excellent minimal-json library, likewise available under the MIT License. Package names have all been changed, to prevent any conflicts should you happen to be using a different version of that library elsewhere in your project dependencies.