boilerplate

boilerplate

• envconfig
  • Supported Stores
    • DynamoDB
    • Lambda
    • HTTP
  • Usage
    • Create a function to load app configuration from env vars
    • How to define env var DB_URI
      • Option 1: Literal value
      • Option 2: Retrieve scalar value from AWS Secrets Manager
      • Option 3: Retrieve JSON value from AWS Secrets Manager

Created by gh-md-toc

envconfig

Supported Stores

aws-secretsmanager: CONFIG_VAR=aws-secretsmanager:region:secret_name[:field_name]
aws-parameterstore: CONFIG_VAR=aws-parameterstore:region:parameter_name[:field_name]
aws-s3:             CONFIG_VAR=aws-s3:region:bucket_name,object_name[:field_name]
aws-dynamodb:       CONFIG_VAR=aws-dynamodb:region:table_name,key_name,key_value,value_attr[:field_name]
aws-lambda:         CONFIG_VAR=aws-lambda:region:func_name,key_name,key_value,body_field[:field_name]
#http:              CONFIG_VAR=#http::method,proto,host,path,body_base64,token[:field_name]

:field_name is optional. If provided, the object will be decoded as JSON/YAML and the specified field name will be extracted.

Examples:

export DB_URI=aws-secretsmanager:us-east-1:database:uri
export DB_URI=aws-parameterstore:us-east-1:/microservice9/mongodb:uri
export DB_URI=aws-s3:us-east-1:bucketParameters,app7/mongodb.yaml:uri
export DB_URI=aws-dynamodb:us-east-1:parameters,parameter,mongodb,value:uri
export DB_URI=aws-lambda:us-east-1:parameters,parameter,mongodb,body:uri

echo -n '{"parameter":"mongodb"}' | base64
eyJwYXJhbWV0ZXIiOiJtb25nb2RiIn0=

export DB_URI=#http::GET,https,tttt.lambda-url.us-east-1.on.aws,/,eyJwYXJhbWV0ZXIiOiJtb25nb2RiIn0=,Bearer secret:uri

DynamoDB

export DB_URI=aws-dynamodb:us-east-1:parameters,parameter,mongodb,value:uri
#           Table: parameters
#             Key: parameter=mongodb
#  Attribute name: value
# Attribute value: {"uri":"mongodb://127.0.0.1:27001/?retryWrites=false"}

Lambda

export DB_URI=aws-lambda:us-east-1:parameters,parameter,mongodb,body:uri
#       Function: parameters
#        Request: {"parameter":"mongodb"}
# Response field: body
#       Response: {"statusCode": 200,"body": "{\"uri\": \"mongodb://localhost:27017/?retryWrites=false\"}"}

HTTP

export DB_URI=#http::GET,https,tttt.lambda-url.us-east-1.on.aws,/,eyJwYXJhbWV0ZXIiOiJtb25nb2RiIn0=,Bearer secret:uri
#   Method: GET
# Protocol: https
#     Host: tttt.lambda-url.us-east-1.on.aws
#     Path: /
#     Body: {"parameter":"mongodb"} (base64 encoded as eyJwYXJhbWV0ZXIiOiJtb25nb2RiIn0=)
#    Token: Bearer secret
# Response: {"uri":"mongodb://127.0.0.1:27001/?retryWrites=false"}

Usage

Create a function to load app configuration from env vars

See example function newConfig() below.

Or look at examples/envconfig-example/config.go.

import (
	"github.com/udhos/boilerplate/envconfig"
)

type appConfig struct {
	databaseURI  string
	databaseCode int
	databaseTidy bool
}

func newConfig(env *envconfig.Env) appConfig {
	return appConfig{
		databaseURI:  env.String("DB_URI", "http://test-db"),
		databaseCode: env.Int("DB_CODE", 42),
		databaseTidy: env.Bool("DB_TIDY", false),
	}
}

How to define env var DB_URI

Option 1: Literal value

export DB_URI=http://real-db

Option 2: Retrieve scalar value from AWS Secrets Manager

If you prefix env var value with aws-secretsmanager:, the envconfig package will try to fetch it from AWS Secrets Manager.

Format:
export CONFIG_VAR=aws-secretsmanager:region:secret_name

Example:
export DB_URI=aws-secretsmanager::database_uri

# `database_uri` is the name of the secret stored in AWS Secrets Manager
# The secret `database_uri` could store any scalar value like: `http://real-db`

Option 3: Retrieve JSON value from AWS Secrets Manager

If you append ":<json_field>" to env var value, after the secret name, the package envconfig will retrieve the secret from AWS Secrets Manager and will attempt to extract that specific JSON field from the value.

Format:
export CONFIG_VAR=aws-secretsmanager:region:secret_name:json_field

Example:
export DB_URI=aws-secretsmanager::database:uri

# `database` is the name of the secret stored in AWS Secrets Manager
# `uri` is the name of the field to be retrieved from the JSON value
# The secret `database` should store a JSON value like: `{"uri":"http://real-db"}`
# In this example, the env var DB_URI will be assigned the value of the JSON field `uri`: `http://real-db`.