Create Rest Web API in Golang

Initial setup

    go mod init github.com/yonyu/go-webapi

    git remote add origin git@github.com:yonyu/go-webapi

    git checkout -b version-2-001
    git status
    git add -A
    git commit -m "Initial commit"
    (no longer supported) git push origin master

Tools needed

go version

git version

docker -v

docker-compose -v

task -h

Architecture

                                                    Business Logic                       Database
                                                          ^
                                                          |

Requests >>>> HTTP --> Service --> Repository | ⌵
External APIs Client

Project layout

go-webapi/ cmd/ main.go server/

Open the terminal and run the command:

go run cmd/main.go

go-webapi/ internal/ comment/ comment.go

struct construction: https://go.dev/doc/effective_go#composite_literals

Decouple the concrete implementation from database by returning struct

Add error handling

Add Implementation placeholder

Propagating context (Trace ID and Request ID), that is helpful when debugging multiple services

Dockerizing the app

Create Dockerfile

    docker build -t go-webapi .
    docker run go-webapi

Docker compose

Create docker-compose.yml file

    docker-compose up

Create Taskfile.yml

Create Taskfile.yml file

    task build
    task test

Connecting to database

    go get github.com/jmoiron/sqlx github.com/lib/pq

    task run

Migrating the database

    go get github.com/golang-migrate/migrate/v4

to remove the pack by go get:

    go clean -i github.com/golang-migrate/migrate/v4

Step 1. create dbmigration.go and make other changes

Step 2. create migration SQL scripts

    task run

Open a new terminal:

    docker ps
    docker exec -it 95f8c33edaf4 bash
    psql -U postgres
    \dt
    \d+ comments;

Implement database package

Step 1: Created comment.go

Step 2: task run

another terminal: docker ps docker exec -it 95f8c33edaf4 bash psql -U postgres insert into comments (id) values('84f279ee-5aef-4ddb-8ae7-0d561a7944b2'); select * from comments; \q exit

Rename internal/comment/ to internal/domain/

Corresponding refactoring

Rename internal/db/comment.go to internal/db/comment_repository.go

Rename internal/db/ to internal/database/

Rename internal/db/db.go to internal/database/database.go

Step 3: implement other database accesses

    go get github.com/satori/go.uuid

    task run

in a new terminal: docker exec -it 95f8c33edaf4 bash psql -U postgres select * from comments; \q exit

Implement Delete and Updateoperations

DeleteComment

UpdateComment

Create the transport layer (containing the logic of transport)

Create internal/transport/http/handler.go

Scaffolding handler

    go get github.com/gorilla/mux

    task run

Launch a zsh terminal:

    curl http://localhost:8080/hello

Gracefully shutdown

Run Server.ListenAndServe() in a Go routine. The main routine is blocked until the channel receives a signal.

Implement the handler function

Create transport/http/comment.go

    type Store interface {
            GetComment(context.Context, string) (Comment, error)
            PostComment(context.Context, Comment) (Comment, error)
            DeleteComment(context.Context, string) error
            UpdateComment(context.Context, string, Comment) (Comment, error)
    }

Implement PostComment()

in bash shell:

    task run

in zsh:

    curl --location --request POST 'http://localhost:8080/api/v1/comment' \
    --header 'Content-Type: application/json' \
    --data-raw '{
            "slug": "hello",
            "body": "body",
            "author": "me"
    }'

Implement GetComment()

    curl --location --request GET 'http://localhost:8080/api/v1/comment/2415b52e-3903-4c94-9bc4-4cef28fcf5aa'

Implment UpdateComment()

    curl --location --request PUT 'http://localhost:8080/api/v1/comment/2415b52e-3903-4c94-9bc4-4cef28fcf5aa' \
    --header 'Content-Type: application/json' \
    --data-raw '{ "Slug": "/testing-put", "Body": "body", "Author": "Yong" }'

Implement DeleteComment()

    curl --location --request DELETE 'http://localhost:8080/api/v1/comment/2415b52e-3903-4c94-9bc4-4cef28fcf5aa'

Versioning Api endpoint

For breaking changes, create a new version of the endpoint. For example:

    h.Router.HandleFunc("/api/v2/comment", h.PostCommentV2).Methods("POST")

Implementing middleware

Create a file internal/transport/http/middleware.go

    curl --location --request POST 'http://localhost:8080/api/v1/comment' \
    --header 'Content-Type: application/json' -v\
    --data-raw '{
            "slug": "hello",
            "body": "body",
            "author": "me"
    }'

Handling error with middleware:

get request got the following error when using a non-existing comment ID:

    comments-rest-api  | Retrieve a domain
    comments-rest-api  | error fetching the domain by uuid: sql: no rows in result set
    comments-rest-api  | 2024/12/30 05:22:24 failed to fetch domain by ID

Logging middleware

    go get github.com/sirupsen/logrus

    to test:

    task run
    http://localhost:8080/api/v1/comment/2415b52e-3903-4c94-9bc4-4cef28fcf5aa

Timeout middle

Apply and implement a timeout middleware

Request validation

https://github.com/go-playground/validator

    go get github.com/go-playground/validator/v10

Tesing the services

Overview

First to test the database layer

Then test the Service layer (domain)

mock tests

Finally, test the Transport layer

Integration tests

1. The database layer

internal/database/comment_test.go

go get github.com/stretchr/testify/assert

go test ./... -v
go test -tags=integration ./... -v

To test

task integration-test

Acceptance tests

create go-webapi/tests/health_test.go
modify Taskfile.yml
go get github.com/go-resty/resty/v2

go get github.com/dgrijalva/jwt-go

task acceptance-tests

CI/CD with CircleCI

Create go-webapi/.circle/config.yml