Foundational Go library

This foundational Go library conforms to Coupa's microservice standard and can be used in Go based applications.

Getting Started

Prerequisites

Go version 1.10.* or higher

Structure

Foundation lets you set up your application to use logging, health checks, and metrics conforming to the microservice standard.

To set up logging, you need to call logging.InitStandardLogger early in your application. To set up statsd metrics, you need to define a factory function func() *metrics.Statsd and set it using metrics.SetFactory function (please see the details in the example below).

Foundation also provides Gin-backed (https://github.com/gin-gonic/gin) server, several middlewares, and health check mechanisms to support the microservice standard.

An example of usage:

import (
  "github.com/coupa/foundation-go/config"
  "github.com/coupa/foundation-go/health"
  "github.com/coupa/foundation-go/logging"
  "github.com/coupa/foundation-go/metrics"
  "github.com/coupa/foundation-go/middleware"
  "github.com/coupa/foundation-go/server"
  "github.com/gin-gonic/gin"
  log "github.com/sirupsen/logrus"
)

func main() {

  //***************************** Logging ***********************************

  //logging.InitStandardLogger must be called early in your app.
  logging.InitStandardLogger("v1.0.0")

  //The InitStandardLogger above will make logrus' standard logger to use the standard format
  log.Info("this log will have the required standard fields")

  //************************* Secrets Manager *******************************

  //To use the GetSecrets or WriteSecretsToENV functions in config/aws_secrets_manager.go,
  //you need to have AWS credentials configured as environment variables or configure
  //AWS EC2 IAM roles to allow access (see https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/configuring-sdk.html).
  //If you have other ways of authentication, you can provide your own session with
  //GetSecretsWithSession or WriteSecretsToENVWithSession.

  //This will grab values from secrets whose key names are in the format of an
  //environment variable name (all uppercase characters with digits and connected
  //with underscores. No dash or other symbols) and set them to corresponding
  //environment variables.
  err := config.WriteSecretsToENV("dev/application/for_testing")

  //So if "dev/application/for_testing" has {"GOOD_ENV1":"good","bad-env2":"bad"},
  //the above method will set only GOOD_ENV1="good" and not the other one

  //***************************** Metrics ***********************************

  //These enable metrics to know how to initialize the Statsd client
  factory := func() *metrics.Statsd {
    return metrics.NewStatsd("address", "prefix.", "version", "app", 1.0)
  }
  metrics.SetFactory(factory)

  //****************************** Server ***********************************

  svr := server.Server{
    Engine:               gin.New(),
    AppInfo:              &health.AppInfo{...},     //You should fill in this info
    ProjectInfo:          &health.ProjectInfo{...}, //You should fill in this info
    AdditionalHealthData: map[string]*health.AdditionalHealthData{},
  }

  //*** Middlewares ***

  //Register the middlewares first before registering routes
  svr.UseMiddleware(middleware.Correlation())
  svr.UseMiddleware(middleware.Metrics())
  svr.UseMiddleware(middleware.RequestLogger(false))

  //*** Health ***

  //Declare or create the health checks that you want
  dbCheck := health.SQLCheck{
    Name: "mysql",
    Type: "internal",
    DB: ...,  //Some *sql.DB
  }
  serviceCheck1 := health.WebCheck{
  	Name: "some web 1",
  	Type: "service",
  	URL:  "https://some.web/health",
  }
  serviceCheck2 := health.WebCheck{
  	Name: "some web 2",
  	Type: "service",
  	URL:  "https://some.web2/health",
  }

  ahd1 := health.AdditionalHealthData{
    DependencyChecks: []HealthChecker{dbCheck, serviceCheck1},
    DataProvider:    func(c *gin.Context) map[string]interface{}{
      return map[string]interface{}{
        "custom": "data",
      }
    },
  }

  adh2 := health.AdditionalHealthData{
    DependencyChecks: []HealthChecker{dbCheck, serviceCheck1, serviceCheck2},
  }

  //Register 3 versions of the detailed health. Note that they are different as
  //"/v1" has additional custom data but does not have `serviceCheck2` dependency check,
  //and "/v3" has no dependency or additional data.
  svr.RegisterDetailedHealth("/v1", "v1 of app detailed health", ahd1)
  svr.RegisterDetailedHealth("/v2", "v2 of app detailed health", ahd2)
  svr.RegisterDetailedHealth("/v3", "v3 without custom data or dependency check", nil)
  svr.RegisterSimpleHealth()

  someHandler := func(c *gin.Context) {
    //Emitting statsd metric
    metrics.Increment("interesting.metric")

    logging.RL(c.Request, c.Writer).Info("This is logging with correlation ID")

    c.JSON(200, `{"he":"llo"}`)
  }

  //Register routes
  svr.Engine.GET("/test", someHandler)

  svr.Engine.Run(":80") //svr.Engine.Run() without address parameter will run on ":8080"
}

Env variables

health.AppInfo{}.FillFromENV and health.ProjectInfo{}.FillFromENV will by default load from these Env variables:

APPLICATION_NAME
HOSTNAME
SERVER_BIND_ADDRESS
PROJECT_REPO
PROJECT_HOME
PROJECT_OWNERS: Comma-separated owner names.
PROJECT_LOG_URLS: Comma-separated log URLs.
PROJECT_STATS_URLS: Comma-separated metrics URLs.

Enabling Secrets Manager Tests

This is for foundation-go contributors to run secrets manager tests in foundation-go.

Foundation-go has tests that actually connect to AWS secrets manager. These tests are not run in regular go test ./... command.

To run these tests, you need to pre-setup the AWS credentials (mostly likely in environment variables or config files, see https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/configuring-sdk.html), make sure the target secret of name dev/application/for_testing exists and have:

{
  "TEST_DESCRIPTION": "For testing",
  "not_set_to_env":"Will not be set to your ENV variables"
}

as data. Then run test with this environment variable and command: TEST_SECRETS_MANAGER=true go test ./....

Enabling Redis Tests

This is for foundation-go contributors to run redis tests in foundation-go.

Foundation-go has tests that actually connect to a local Redis server. These tests are not run in regular go test ./... command.

To run these tests, you need to run a local Redis server without password on the port 6379, then run test with this environment variable and command: TEST_REDIS=true go test ./....