pkg envsecret

tl;dr Exposes envsecret.Process, designed to follow envconfig.Process and retrieve secrets from stores such as Vault and AWS Secrets Manager.

Summary

Package secret wraps interaction with secret stores and is designed to complement envconfig, though it can work independently. Local, Vault and AWS Secrets Manager stores are included, but custom stores can implement envsecret.Store.

Define a configuration specification suitable for envconfig, but use an implementation envsecret.Secret in place of any remotely stored secrets. The package provides a few implementations for common use cases, e.g. envsecret.String, envsecret.Login, and others.

Instead of configuring the secret value in the environment variable, configure it's secret identifier, as defined by the given secret store: e.g. an ARN if using AWS Secrets Manager or a Vault secret path.

Processing by envconfig should populate each secret's identifier by by implementing envconfig.Decoder. Then, envsecret.Process will retrieve each requested secret and populate it according to it's Decode method.

By default, secrets are not required. This means an error will only be returned if a secret is marked as required:"true" in the configuration struct tags.

Example

Given the following environment configuration and secrets configured in AWS Secrets Manager:

APP_DEBUG=true
AWS_REGION=us-west-2
APP_SOME_SECRET=somesecret-name-in-aws
APP_REQUIRED_SECRET=requiredsecret-name-in-aws
APP_ANOTHER_SECRET=somesecret-name-in-aws
APP_PUBLIC_KEY=mykeypair
APP_CREDENTIALS=database-credentials-123

The code below will populate the configuration struct with the requested secret values:

// Configure a specification struct for envconfig.
type Config struct {

    // Non-secret types can be mixed freely with secret types.
    Debug  bool
    Region string `envconfig:"AWS_REGION" default:"us-east-1"`

    // SomeSecret will default to the "value" key found in the secret 
    // named "somesecret-name-in-aws"
    SomeSecret envsecret.String `split_words:"true"`

    // RequiredSecret will cause an error if its key "requiredsecret-name-in-aws" 
    // is not present in the config.
    RequiredSecret envsecret.String `split_words:"true" required:"true"`

    // AnotherSecret will also use the secret found at "somesecret-name-in-aws" 
    // but with a different key than the default, "some_other_key"
    AnotherSecret envsecret.String `split_words:"true" secret_keys:"some_other_key"`

    // The PublicKey type expects a base64 encoded key from which 
    // to construct an *rsa.PublicKey.
    PublicKey envsecret.PublicKey `split_words:"true"`

    // Login provides a username and password pair.
    Credentials envsecret.Login
}

func main() {

    // Process as normal with envconfig. This will populate the secret store
    // identifiers necessary for secret retrieval.
    var config Config
    envconfig.MustProcess("app", &config)

    // Set up a secret Store, in this case AWS Secrets Manager.
    awsSession, _ := session.NewSession(aws.NewConfig().WithRegion(config.Region))
    sm := secretsmanager.New(awsSession)
    secretStore := envsecret.NewSecretsManager(sm)

    // Retrieve the secrets from the Store and populate the config 
    // with their secret values.
    envsecret.MustProcess(&config, secretStore)

    // Types implementing Secret determine how to populate themselves via 
    // their implementation of Decode. For example, the envsecret.String type 
    // populates a Value field with the secret string value, and envsecret.PublicKey 
    // populates a Key field with a constructed rsa.PublicKey.
    fmt.Println(config.SomeSecret.Value)
    fmt.Println(config.PublicKey.Key)
}