Blog app microservices

This is a small application in microservices. A user can create a post and other users can comment.

Initial goal is create the logic of microservices and after host in Kubernetes. If you want to read how to deploy the application in Kubernetes (I use GKE - Coogle Kubernetes Engine) with Terraform the follow then link https://github.com/AposLaz/Terraform/tree/main/kubernetes-cluster/gke.

Build With

Architecture

Project Structure

blog-microservices/
├── client/
├── nginx/
├── comments/
├── posts/
├── query-posts-service/
├── kafka/
├── files/  ## images etc.
├── k8s-yamls/ ## for Kubernetes
└── README.md

For every service created a specific image in docker hub. Expect nginx. There is a .env file where exist all configuration for ports, hosts etc. Use your specific values or let defaults.

If you want to learn more about application read the Documentation below

Getting Started

Production

1. Clone repository

   $ git clone https://github.com/AposLaz/Blog-microservices.git
   	
   $ cd Blog-microservices
   
   # Remove current origin repo
   $ git remote remove origin  

2. Start Application using Docker 🐋 https://www.docker.com/

   $ docker-compose up -d
   
   # wait 30seconds

3. Open http://localhost:3050/ on broswer and create your posts.

Development

1. Clone repository

   $ git clone https://github.com/AposLaz/Blog-microservices.git
   	
   $ cd Blog-microservices
   
   # Remove current origin repo
   $ git remote remove origin  

2. Start Application using Docker 🐋 https://www.docker.com/

   $ docker-compose -f docker-compose-dev.yml up -d
   
   # wait 30seconds

3. Open http://localhost:3050/ on broswer and create your posts.

Documentation

If you want to make changes or learn how my application works read the documentation below

API structure

Frontend

Client Service

Client is the frontend application in which user can

1. Create Posts
2. Display Posts
3. Comment in Posts
4. Display Post with comments

API

In API table there are some environment variables. Check them below.

Action	HTTP request	URI	Folder/file
Create Posts	POST	${REACT_APP_POST_HOST}/posts	client/src/api/posts-api.js
Get Posts	GET	${REACT_APP_POST_HOST}/posts	client/src/api/posts-api.js
Create Comments	POST	${REACT_APP_COMMENT_HOST}/posts/{post_id}/comments	client/src/api/commnets-api.js
Get Comments from Specific Post	GET	${REACT_APP_COMMENT_HOST}/posts/{post_id}/comments	client/src/api/commnets-api.js
Get Posts & Comments	GET	${REACT_APP_QUERY_HOST}/posts	client/src/api/post-comments-api.js

ENVIRONMENT VARIABLES

All environment variables exist in .env file in root folder.

⚠️ Change Variables: Be very careful here! Recommend don't change Variablies in .env file. But you are free to change them. If you change the Variables then you have to change config file in nginx/ folder. Check below in Section Config NGINX.

Variable	Info	Folder/file
${REACT_APP_POST_HOST}	Container name of Posts Service	client/src/config/config.js
${REACT_APP_COMMENT_HOST}	Container name of Comments Service	client/src/config/config.js
${REACT_APP_QUERY_HOST}	Container name of Query Service	client/src/config/config.js
${REACT_APP_PORT}	Port for Client	Exists only in .env file

⚠️ If you change ${REACT_APP_PORT} then you have to edit the default.conf file in path client/nginx/default.conf. Edit the port in line listen 3000; and change 3000 with you port.

---

Backend

Posts Service

Action	HTTP request	URI	Folder/file
Create Posts	POST	http://localhost:{POST_PORT}/posts	posts/index.js
Get Posts	GET	http://localhost:{POST_PORT}/posts	posts/index.js

ENVIRONMENT VARIABLES

All environment variables exist in .env file in root folder.

⚠️ Change Variables: Be very careful here! Recommend don't change Variablies in .env file. But you are free to change them. If you change the Variables then you have to change config file in nginx/ folder. Check below in Section Config NGINX.

Variable	Info	Folder/file
${POST_PORT}	The port in which run Posts Service	posts/config/index.js
${POST_TOPIC}	Kafka Topic in which Posts Service sends the created Post	posts/config/index.js
${KAFKA_BROKERS}	All Kafka Brokers in Cluster	posts/config/index.js

request structure:

/*
    When someone Create a Post the structure is the Following (Example)
*/
{
    id: 123,  //Post Id
    title: 'FirstTitle' //The Title of Post
}

database:

ID	Title
123	FirstTitle

---

Comments Service

Action	HTTP request	URI	Folder/file
Create Comments	POST	http://localhost:${COMMENT_PORT}/posts/:{id of Post}/comments	comments/index.js
Get Comments	GET	http://localhost:${COMMENT_PORT}/posts/:{id of Post}/comments	comments/index.js

ENVIRONMENT VARIABLES

All environment variables exist in .env file in root folder.

⚠️ Change Variables: Be very careful here! Recommend don't change Variablies in .env file. But you are free to change them. If you change the Variables then you have to change config file in nginx/ folder. Check below in Section Config NGINX.

Variable	Info	Folder/file
${COMMENT_PORT}	The port in which run Comments Service	comments/config/index.js
${COMMENT_TOPIC}	Kafka Topic in which Comments Service sends created Comments for a specific Post	comments/config/index.js
${KAFKA_BROKERS}	All Kafka Brokers in Cluster	comments/config/index.js

request structure:

/*
    When someone Create a comment the structure is the Following (Example)
*/
{
    id: j23, //commentId
    comment: 'My first Comment' //here there is the comment
}

database:

ID	Comment
j23	My first Comment

---

Apache Kafka

Apache Kafka have at least 2 Topis:

PostCreated_topic && CommentCreated_topic

/* When we create a `post/` a message sends to PostCreated_topic (Example) : */

    {
        id: 123, //Post Id
        title: 'FirstTitle' //The Title of Post
    }

/* When we create a `comment/` a message sends to CommentCreated_topic (Example) : */

    {
        id: j23, //commentId
        comment: 'My first Comment'
        postId: 123 //Post Id
    }

---

Query Service

When we want to fetch a post with all of its comments we query for the post with comments in query-posts-service/ Service.

This service accepts messages from Kafka topics (PostCreated, CommentCreated)

Consumers of Apache Kafka receive all the messages from Topics PostCreated && CommentCreated. So, the table for its database looks like:

database:

Post_ID	Title	Comments
123	FirstTitle	{id: j23, comment: 'My first Comment'}

Action	HTTP request	URI	Folder/file
Get Posts with Comments	GET	http://localhost:${QUERY_PORT}/posts	query-posts-service/index.js

All data store in a MongoDB Database in which we use mongo-express which is admin interface for MongoDB.

ENVIRONMENT VARIABLES

All environment variables exist in .env file in root folder.

⚠️ Change Variables: Be very careful here! Recommend don't change Variablies in .env file. But you are free to change them. If you change the Variables then you have to change config file in nginx/ folder. Check below in Section Config NGINX.

Variable	Info	Folder/file
${QUERY_PORT}	The port in which run Comments Service	query-posts-service/config/index.js
${POST_TOPIC}	Kafka Topic in which Query Service accept the created Posts	query-posts-service/config/index.js
${COMMENT_TOPIC}	Kafka Topic in which Query Service accept created Comments for a specific Post	query-posts-service/config/index.js
${KAFKA_BROKERS}	All Kafka Brokers in Cluster	query-posts-service/config/index.js

---

kafka Service

Kafka Service is a Kafka admin client who can create Topics with many partitions and replicas. User can define the name of topics, number of partitions and number of replicas.

In Docker compose we can declare Environment Variables for these values.

ENVIRONMENT VARIABLES

All environment variables exist in .env file in root folder.

Variable	Info	Folder/file
${KAFKA_TOPICS}	All topics that we want to create	kafka/config/index.js
${KAFKA_REPLICATION_FACTOR}	Replication factor for topics ${KAFKA_TOPICS}	kafka/config/index.js
${KAFKA_NUM_PARTITIONS}	Number of partitions for topics ${KAFKA_TOPICS}	kafka/config/index.js
${KAFKA_BROKERS}	All Kafka Brokers in Cluster	kafka/config/index.js
${KAFKA_APP}:	Kafka client id

---

Config NGINX

With NGINX we