gopher

GoLang Google Cloud Function Firestore Template

Contents

1. Stack
2. Useful Docs
3. Description
4. Responses
5. Getting Started
6. Testing
7. Deployment
8. License

Stack

• Written in GoLang
• Hosted on a Google Cloud Function
• Backend/Database is hosted via Google Cloud Firestore

Useful Docs

• Outputting JSON in GoLang https://gobyexample.com/json
• GoLang with Firestore Examples + Quick Start https://github.com/GoogleCloudPlatform/golang-samples/tree/master/firestore
• official GoLang Package Docs for firestore package https://pkg.go.dev/cloud.google.com/go/firestore?tab=doc

Description

This is the skeleton of a google cloud function written in GoLang for a lookup/catalog service with a Google Firestore database backend. For example.

GET request to https://region-account.cloudfunctions.net/FunctionName?object_id=1

POST request to https://region-account.cloudfunctions.net/FunctionName with form parameter of object_id = 1

These can both return a flattened JSON object from the collection you specify

{"object_id":"1", "name":"Object 1", "description":"oooh.... shiny"}

Responses

• 200 / http.StatusOK - This means the object was found, will also return the object in JSON format
• 422 / http.StatusUnprocessableEntity - The ID was not passed in, or wasn't a number
• 422 / http.StatusUnprocessableEntity - The query didn't return any results
• 500 / http.StatusInternalServerError - The function cannot connect to Firestore
• 500 / http.StatusInternalServerError - The Object retrieved cannot be converted to JSON format properly

Getting Started

1. Clone/Download the repository and remove all git references

git clone https://github.com/hallindavid/go-gcpfunc-firestore-template /path/to/project
cd /path/to/project
rm -rf .git

# If desired, init your git repo here
# git init

1. Follow the steps in this link to create a json file to use for credentials https://cloud.google.com/docs/authentication/production#obtaining_and_providing_service_account_credentials_manually

2. Create your .env file in the root directory

3. In your .env file, put the following line of code

GOOGLE_APPLICATION_CREDENTIALS="/full/system/path/to/json-credentials.json"

1. Update the gopher.go file (or copy/paste) to a more suitable name eg: if you are you retrieving users, maybe make it users.go and func Userlookup(...

2. download packages / build the module

go get
go mod init

1. Run it to make sure everything works - see Testing Locally
2. Make your tests
3. perform a go test to make sure everything is working
4. Deploy it - see Deployment

Testing

Quick Test All

go test

Test All With Output

go test -v

Local Testing

in the cmd folder (after you've generated your go.mod file) update the main.go file to import the proper module

package main

import (
	"log"
	"net/http"

	"github.com/hallindavid/go-gcpfunc-firestore-template" //This line will need to be updated
	_ "github.com/joho/godotenv/autoload"
)

func main() {
	http.HandleFunc("/", gopher.FirestoreLookup) //this line will need to point to the correct function (eg. userlookup.LookupUsers)

	log.Printf("Listening on port 8080")
	if err := http.ListenAndServe(":8080", nil); err != nil {
		log.Fatal(err)
	}
}

in terminal/command prompt

go run ./cmd

This will listen on port 8080 and allow you try to postman/browse to your functions

Deployment

Follow deployment steps found here

#eg
gcloud deploy UserLookup --region us-central1 --runtime go113 --trigger-http

Licenses

• GoLange is licensed here: https://golang.org/LICENSE
• GoDotEnv is licensed (MIT) here: https://github.com/joho/godotenv/blob/master/LICENCE
• Firestore is licensed (Apache-2.0) here: https://pkg.go.dev/cloud.google.com/go/firestore?tab=licenses#LICENSE

Use of the GoDotEnv Package

We are using godotenv (https://github.com/joho/godotenv) to set the default Firestore application credentials for testing - but it isn't required for production. You can actually remove the package altogther and do a similar kind of thing in a bashfile

# build.sh in project root directory
export GOOGLE_APPLICATION_CREDENTIALS="/full/system/path/to/json-credentials.json"
go run ./cmd

# test.sh in project root directory
export GOOGLE_APPLICATION_CREDENTIALS="/full/system/path/to/json-credentials.json"
go test
#or go test -v