github.com/hashicorp/vault

The Vault Go client provides a well-designed API for interacting with HashiCorp Vault. The library follows secure-by-default principles with TLS enabled out of the box and proper token handling built into the client. The API surface is clean, with separate packages for different secret engines (KV, PKI, Transit) that make intent clear and reduce misconfiguration risk.

Error handling is generally good with typed errors that don't leak sensitive information in stack traces. The client properly validates inputs and enforces authentication before operations. Token renewal and lifecycle management are handled transparently, which prevents common authentication pitfalls. The library has responsive CVE handling, with security patches typically released within days of disclosure.

The main challenge is the steep learning curve around Vault's authentication model and the verbosity of constructing clients for different secret engines. Documentation assumes familiarity with Vault concepts, making initial integration slower. Dependency management is reasonable with HashiCorp maintaining tight control over the supply chain, though the transitive dependency tree includes several crypto libraries that require attention during security audits.

The Vault Go client gets the job done but feels dated compared to modern Go libraries. The API surface is quite large with separate packages for each secret engine and auth method, which makes discovery challenging. You'll spend time navigating between `api`, `vault`, and engine-specific packages to accomplish basic tasks. The client initialization is straightforward, but configuring TLS, namespaces, and retry logic requires more boilerplate than I'd like.

Error handling is functional but generic - you often get opaque errors that require debugging the actual HTTP response. The library doesn't provide typed errors for common scenarios like permission denied or secret not found, so you're left parsing error strings. Documentation exists but leans heavily on examples rather than comprehensive API references, and many edge cases aren't covered.

Type safety is minimal - secrets come back as `map[string]interface{}` requiring manual type assertions everywhere. The lack of generics support (even in recent versions) means you're constantly casting. IDE autocompletion helps with method discovery, but the sheer number of options and similar-sounding methods can be confusing.

The Vault Go SDK gets the job done but feels like it hasn't kept pace with modern Go development practices. The API surface is quite large and inconsistent - you'll find yourself constantly switching between different client initialization patterns depending on whether you're using KV v1, KV v2, AWS auth, or other engines. Each secret engine often requires its own client setup dance, and the documentation doesn't always make it clear which approach to use.

Error handling is particularly frustrating. Errors are often opaque string-based messages that require parsing or contain minimal context about what went wrong. When authentication fails or a secret path is incorrect, you're left digging through generic HTTP responses rather than getting structured, actionable error types. The lack of strongly-typed response structs for many operations means you end up working with map[string]interface{} more than you'd like.

That said, it's stable and covers the full Vault feature set. If you need comprehensive Vault integration and can invest time learning its quirks, it works. Just expect to write more boilerplate and helper functions than you'd hope for in a modern Go SDK.