What is GitOps in easy way ??


Here we will discuss: "What is GitOps", and "What are its 4 important principles". And lastly, "Why GitOps operator follow a pull-based model ?".

What is GitOps ??



GitOps is made up of two words: Git and Ops. Git is where you keep your desired manifest(or configurations) that you want to deploy in your cluster(or environment). And Ops refers to Operation. Operation refers to the environment where the things are operated to ensure that the actual state or live state of that environment must be the same as the desired state in the git. To achieve that from the actual state to the desired state an operation is performed inside the environment.  Such an environment could be a Kubernetes cluster. So, anything that you want to deploy in the Kubernetes simply put it in the git. From git, the GitOps operator(i.e. Argo CD) will deploy to the Kubernetes cluster. To understand the GitOps better we need to understand 4 principles of it:

4 Principles of GitOps:

1. Declarative Vs Imperative approach:

GitOps demands the entire system including infrastructure and application manifest to be declared in a declarative state. Declarative means an end state or desired state we want to achieve is defined via manifest and placed in Git.  For example, suppose you want to start 3 containers, to do that imperatively, you need to run commands manually. Whereas declaratively, you only need to declare the “number of containers” in the manifest file and unlike imperatively you don’t need to remember commands.
Once you declare your desired state in the manifest, it needs to be pushed to Git, and from Git, it will be automatically fetched by the GitOps operator and pushed to the environment or cluster.

NOTE: Why does it discourage the use of imperative approaches ??

The imperative approach uses a series of explicit commands to change the desired state which makes reconciliation difficult because it does not store any state.

2. Git:

All the declarative files also known as the desired state are stored in a git repository. Git provides version control and also enforces immutability. Since the desired state is stored and versioned it is essentially known as the source of truth. Once we store the desired state in git, we must allow any changes to the state to be applied automatically.

3. GitOps Operator:

Also known as a Software agent, as the Git repo is updated by the team members via pull request, it's now the duty of a software agent to pull these new changes every 3 minutes from Git and update the state of the target environment through reconciliation.

NOTE:
  • Later we will understand that GitOps Operators work on a Pull-based Model.
  • Live State or Current state: Actual state deployed in the environment or cluster.
  • Target State or Desired state: The desired state is represented resent in the Git repository.

So, the job of the software agent is to implement reconciliation in order to sync the live state of the cluster with the desired state present in Git.

NOTE: The GitOps operator runs in one of the clusters and can make or push changes to multiple clusters as well.

4. Reconciliation:

The continuous looping in a defined interval to ensure that the desired state described in the Git repository with the Live state in the cluster is known as Reconciliation. It is implemented by the software agent known as the GitOps operator. Later in Argo CD architecture, we will learn that the Application Controller (core components of Argo CD ) is nothing but the GitOps operator.
By default, every 3 minutes the GitOps operator looks at the git repo and reconciles it.

The reconciliation involves 3 steps:




  • Observe:
    • The GitOps operator checks the git repo for any changes in the desired state.
  • Diff:
    • In this state, the operator compares the resources received from Git to the live state of the cluster.
  • Act:
    • It uses the reconciliation function and tries to match the actual state to the desired state.


This control loop is being carried every time the reconciliation loop is carried by the GitOps operator.

NOTE:
  • Control loop == Obser + Diff + Action
  • The GitOps operator also makes sure that the entire system is self-healing to reduce the risk of human errors.

Overall when we look at the term called "GitOps". It means considering Git as a source of truth. From where the operation is carried out by the GitOps operator every 3 minutes to achieve the desired state via the reconciliation process. Basically, GitOps is limited to the Cloud-Native environment i.e. Kubernetes environment only, that's why it is considered to be part of DevOps.

Why GitOps Operator follow a pull-based model rather than a push-based model ??

In the Pull-base model, the GitOps operator itself pulls the changes from Git every 3 minutes. Whereas in the push-based model, Git pushes the changes to the environments or cluster.

For the push-based model, the "CI/CD" needs to have read-write access to the Kubernetes cluster. This raises a potential issue and hence not recommended. Apart from that CI/CD system also has read-write access to the container registry.

Whereas the pull-based model has read-write access to the container registry but not to the Kubernetes cluster.

Managing secrets in a pull-based model is a bit hard. As per the GitOps principle, the secret also has to be declared in a git repo as plaintext(i.e. base64). But we can't do so, to avoid the plain-text secret we use the sealed secret or Harshicorp vault or many more to encrypt the secret and then push to git.

Till now we have learned about GiOps principle and pull-based mode. Next, we will learn about Argo CD. That's all for today. Great to see you all upgrading your knowledge. Keep growing and keep learning !!



Comments

Post a Comment

All Post

Argo CD 101

Image
Why Argo CD ?? Because it fulfills all the points of the GitOps principle . As it extends the benefits of declarative specifications, acting as a GitOps Operator, follows a pull-based approach,  and considers Git as a source of truth for configuration management. It follows a pattern of reconciliation i.e. continuously performing a control loop every 3 minutes to achieve the desired state by fetching the desired configuration from Git. Let’s understand it in more detail, how can we achieve or implement GitOps using Argo CD ?? We all know that every company and every developer uses Git as a source code management software to store code. Developers can commit their infrastructure configurations, such as Kubernetes resource manifest, in Git to create the environment needed for application deployment. Once a developer implements a feature( with new applications and Kubernetes configurations) and merges the main branch. With the help of the GitOps agent or GitOps operator, Argo CD will imme
Read more

Logging ??

Image
 Today we will learn about the following things: What is logging ?? Why do we need logging ?? How can logging help us ?? Why suddenly from the last 5-10 years logging has been evolving ?? Logging tools ?? First thing first, let's start with logging. Logging is human-readable information that is primarily text in nature. Logging is triggered or generated when some kind of event occurs, such event is known as a log event.  Each logging message contains the timestamp, which signifies the time at which the event occurred. Now let, us understand why we need logging.  Importance of logging ?? In today's world software all around the world captures the whole market. By definition, Software is a program that is made up of millions of lines of code.  The programmer while writing the code adds the logs at all places to know the code behaviors as well as unexpected ones.  The logs can be of types such as ERROR, WARN, INFO, FATAL, DEBUG, TRACE, etc.     NOTE : Logs are also added to know w
Read more

AWS and its Services ??

Image
So, in a previous blog, we learned about cloud computing and its importance . Here we will start with the popular cloud service provider, Amazon Web Services(AWS).  AWS or Amazon Web Services is a cloud service provider that offers various cloud computing services that are accessible via the public internet. The popular services provided by AWS are:  Virtual machine(EC2),  Virtual Network(VPC), Restrict access to cloud resources(IAM), etc.  Executing functions(Lambda),  Automating your infrastructure(CloudFormation),  Object Storage(S3),  Block Storage for Virtual Machines(EBS),  Running and Managing Containers(ECS and fargate),  Network Filesystem(EBS),  SQL database(RDS),    Load Balancer(ELB),   Monitoring and logging(CloudWatch),  We will learn these services one by one.  In this blog, we will cover Virtual Machines (EC2). These services can be accessed in four ways: Console :  access AWS services through a graphical user interface (GUI) CLI :    to manage and access AWS services
Read more

Observability 101

Image
Hey Everyone !! Good to see you all here to learn Prometheus. This blog is the prerequisite to learning Prometheus.  Prometheus is a part of Observability. Before wasting our time, let's jump into the topic called Observability. Observability Fundamentals What is Observability ?? Observability == Observe + Ability. Observability is made up of 2 words: Observe and Ability .  Observe means to observe the data generated from the system, and the ability  means to measure and understand the system's state based on the generated data.  In the broader sense, Observability gives you the insight of the system's internal working of each component. And that helps while troubleshooting an issue. From where does the concept of Observability come in?? In the early days when applications were deployed in Monolithic structures, humans were able to monitor each component present in the system/server due to the limited number of components. As the microservice application started to boom,
Read more

Prometheus Architecture...

Image
  Prometheus Architecture Look at the below figure, and we can see that Prometheus has major 3 things:  to pull Metrics ,  store it in the Time-Series database , a nd  allow third parties to retrieve metrics using PromQL Metrics are mainly pulled from 3 sources: PushGateway , Exporters , and Instrumentation . These pulled metrics are then stored in a time-series database. Later time-series stored metrics are used by third parties such as Prometheus Web UI ,  Alertmanager , and Grafana . Components of Prometheus: There are 3 main components of Prometheus: Retrieval/Pull Metrics This component of Prometheus is mainly responsible for pulling metrics from targets. Targets can be exporters ,   instrumentation , and pushgateway . Time Series Database Once the retrieval collects data from the target, then it transfers to a time-series database. The data are stored in the form of a metric. Each metric is identified by its name and labels. HTTP Server It allows collected time-series data from
Read more

Why need of Cloud Computing ??

Image
  Do you recall the result day of your class 10th and 12th? I believe you do. One thing that caught everyone's attention was the server being down when you accessed the website to check the results. Have you ever wondered why the server experienced downtime?   What was the underlying reason for it? Before we proceed, it's essential to grasp the concept of  servers  and  requests . A server can be a single laptop/computer/node or a cluster of laptops/computers that offer specific services. In this scenario, the server was responsible for running the CBSE   board website through which you could access your results. And second thing it was publicly accessible from the Internet. Another important aspect to consider is the concept of a request. A request is like a command that initiates the execution of a program. When you enter your roll number , name , etc., and press the submit button, it counts as one request. This request is sent to the server, prompting it to execute the
Read more

Build a Slack activity dashboard with Metabase

Image
Introduction In this article, we will be leveraging Airbyte - an open-source data integration platform and Metabase - an open-source way for everyone in your company to ask questions and learn from data - to build the Slack activity dashboard above. Airbyte provides us with a rich set of source connectors, and one of those is the Slack connector which allows us to get data off a Slack. We are going to use this connector to get the data of the Slack Workspace and copy them into a Postgres database destination. And then will connect Postgres database with Metabase in order to create the activity dashboard. Pre-requisites: Git Docker Docker Compose Airbyte Postgres Database Metabase Slack Step 1: Replicating data from Slack to Postgres with Airbyte Deploying Airbyte There are several easy ways to deploy Airbyte, as listed here. For this tutorial, I will just use the Docker Compose method from my workstation:  ``` $ git clone https://github.com/airbytehq/airbyte.git $ cd airbyte $ docke
Read more

Monitoring 101

What is Monitoring ?? Monitoring refers to a tool that collects metrics data, provides a dashboard to visualize the collected data, and generates alerts based on alerting rules.  Monitoring tool =~ Metrics + Visualization + Alerting Monitoring can be done in 2 ways: Blackbox Monitoring Whitebox Monitoring BlackBox Monitoring In this type of monitoring, Applications or Systems are monitored/observed from outside via APIs.  Whitebox Monitoring In this type of monitoring, Applications or Systems are monitored or observed from inside. Here, the system itself is under observation which exposes its internal state data and performance data of the system. This type of internal introspection is very powerful because it exposes the operating system telemetry and the health of each different internal component.  So after collecting internal state data, now we need to know,  what are different ways to expose or send these data ? There are 3 different ways to expose the data: Exported through loggi
Read more

Application Resource in Argo CD

Application Resource   I hope you remember this question in the previous blog: " But how does the Argo CD operator know about the source and destination? ". These all are declared in a custom resource definition(CRD) called Application . It has a source field, a destination field, and many more fields. In order to differentiate b/w source and destination, simply ask this question: For Source : From where to fetch/pull the manifest or configuration files?? For Destination : And where to deploy these manifests or configuration files?? So, the Argo CD operator i.e. application controller uses application resources to achieve the desired state in the cluster with the help of the reconciliation concept. Let's understand the terminologies used in the Application. Argo CD Concepts and Terminologies ?? Terminologies to be used while writing an application resource: The application has 3 main components: Destination : This refers to clusters to which manifest to be deployed or t
Read more