POSTMAN PRE-REQUEST-SCRIPT

 POSTMAN PRE-REQUEST-SCRIPT

POSTMAN provides many features for clubbing ,testing and running API through it. There are many features which can be handy while testing or developing REST APIs.

Pre-Request-Script feature is one the core feature which can be used for setting Token for subsequent request. We can make use of environment variable and set same in header in a collection.

Code snippet for same is ::

CASE 1: When request body contains raw data type.

pm.sendRequest({

url: 'http://localhost:8080/authenticate',

method: 'POST',

header: 'Content-Type:Application/json',

body: {

mode: 'raw',

raw: JSON.stringify({

"username":"admin",

"password":"password"

})

}

}, function (err, res) {

console.log(res.json());

pm.environment.set("authorization", "Bearer " + res.json().token);

});

Now in any request we can set header by setting key and value as "Authorization"  {{authorization}} 

CASE 2: When request body contains formdata type.

const reqObj = {

'method': 'POST',

'url': 'http://localhost:8080/authenticate/token',

'body': {

'mode': 'formdata',

'formdata': [

{'key':'grant_type', 'value':'password'},

{'key':'client_id', 'value':'2'},

{'key':'scope', 'value':'*'},

{'key':'client_secret', 'value':'Tjkjkjk'},

{'key':'username', 'value':'anoop'},

{'key':'password', 'value':'password'}

]

}

};

pm.sendRequest(reqObj, (error, response) => {

if (error) throw new Error(error);

console.log(response.json().access_token);

pm.environment.set("TOKEN",response.json().access_token);

});

Similar to the above request , in this also we can set value dynamic with {{TOKEN}}

CASE 3: Can also add below code under Test tab and set Collection Variable as X-Auth-Token useful for all the request under collection.

var res = pm.response.json();

pm.environment.set('X-Auth-Token', res.access.token.id);

pm.collectionVariables.set('X-Auth-Token',res.access.token.id);

console.log(res.access.token.id);

kubernetes commands

Kubernetes command

1)minikube start --vm-driver=hyperkit  : Will start one node cluster on virtual machine.

2)minikube status : toc check the status of the cluster.

Note: Minikube is just for starting and deleting the cluster specific stuff whereas kubectl is another client which is basically used to interact with cluster and used to perform different task like create deployment etc.

3)kubectl get pod: to list the pods created.

4)kubectl get services: list all the created servces.

5)kubectl get nodes: list all the nodes in clsuter.

6)kubectl create deployment deploymnet1 --image=nginx : create deployment for nginx image wherein the image will be pulled from docker hub.

7)kubectl get deployment :: will list the deployment details.

8)kubectl get replicaset:: will list how many replica set are created for each deployment .

9)kubectl edit deployment :: to edit deployment file.

10)kubectl logs pod-name :

11)kubectl describe pod pod-name:

12)

Containerization Terminologies

Containerization Terminologies 

Kubernetes

Kubernetes is a container orchestration framework built by Google.

k8s

abbreviation for kubernetes ("ubernete" is 8 letters)

Openshift

Openshift is an application Platform-as-a-Service built by Red Hat to extend kubernetes. 

Origin

Openshift  Origin is the open source base for Openshift  installations. Red Hat sells both a cloud (Openshift Online) and on-prem (Openshift Container Platform) offering. Because Origin is open source, it can be installed an managed freely.

Object

Objects

In this context, an object  refers to a k8s object. The definition for an Openshift Object is the same; Openshift extends the k8s API with additional objects.

S2I

Source-to-Image

S2I is a way of building docker images. Though built for the Openshift project, it can be run fully independently, though naturally Openshift has special support for it. The chief benefit of S2I is not having to define a Dockerfile for each application, which implicitly means that there is a standard build methodology per programming language.

There is a default set of S2I base images maintained in the Software Collections GitHub organization.

Helm

Helm is a CLI tool for working with K8s  or Openshift Objects (usually yaml files). It is extensively documented.

Tiller

Tiller is a GRPC server component of the Helm project. The Helm CLI sends requests to Tiller for almost all of its operations, such as running an installation.

Chart

A Chart is a "package" in the Helm world. It contains one or more templated k8s objects. Charts are versioned and published to a Chart Repository.

Chart Repository

Generally, a Chart Repository is a static file server with tarballs of Charts. We can use github pages as its chart repository, and any charts committed to master on your GitHub repo can be automatically published.

Motor

Motor is a RESTful interface for Tiller. In addition to translating rest calls to GRPC, Motor also handles RBAC for installs and release data.

Open Shift CLI Commands

Openshift CLI commands 

1)oc login clusterURL : used to connect to cluster.

2)oc project projectName : used to select project that need to be used.

3)oc get pods : to get pod details.

4)oc get dc : to get deployment configs detail.

5)oc get rc : to get replication controller details.

6)oc get services : to get services details.

7)oc get routes : to get route details.

8)oc scale --replicas=2 podname : to scale replicas to 2 and this will ensure that always there are 2 instances running with auto healing capability which means in case any instance goes down then it will try to bring instance up automatically.

9)oc policy  : to provide access to. different users and groups.

10)oc rsh podname : take remote session of POD for debugging and inspecting.Though pod or a container is immutable. but we can take remote session and check in case there is any issue in POD .

AWS S3 (Simple Storage Service)

 AWS S3 (SIMPLE STORAGE SERVICE

What is S3? 

S3 stands for Simple Storage Service and essentially it's object storage in the cloud. It provides secure, durable, and highly scalable object storage. It allows you to store and retrieve any amount of data from anywhere on the web at a very low cost. So it's extremely scalable.And the other cool thing about S3 is it's really, really simple to use.

S3 is object-based storage, and basically it manages data as objects rather than in file systems or data blocks.So you can upload any file type that you can think of to S3 like like image files, text files,videos, web pages etc. But one important point is that you can only store static content on S3 which means you cannot store any dynamic content for now like installing an OS etc.

The total volume of data and the number of objects you can store is unlimited in S3 and the maximum object size can be upto 5 TB as of today.

Where do we store our file in S3?

We store our files in a thing called a bucket. S3 bucket is basically a folder inside S3. Important thing to know is that  S3 bucket name is universal namespace and all AWS accounts share S3 bucket name globally which means each bucket name shall be globally unique on every creation.

What happens when bucket is created?

let' say you created bucket by the name of  s3bucket , you will see that the new URL  will be generated like below

https:// s3bucket.s3.us-east-1.amazonaws.com/file1.txt

So syntax would be like 

https://{name of bucket}.s3.{region where bucket belongs to}.amazonaws.com/{key name means object which will get persisted like file etc}

We can also have versioning with S3 bucket which could be good option for daily monitoring and tracking. 

Some of the objects associated with S3 are 

      i) key

      ii)Value

     iii)Version Id

     iv)metadata

When bucket is created by default bucket is private and in case you want to make objects public then make sure bucket need to be made public first .

General Response Codes

when you upload a file to S3, if that upload is successful, your browser will receive a HTTP 200 code. There shall be many other response code which you can discover from the AWS doc or I will also try to update those later.

How safe and durable is data stored in S3?

So just remember S3 is a safe place to store your files.The data is always spread across multiple devices and facilities in order to ensure availability and durability.So it's not just in a single data center in a single server.It's always spread across multiple devices and multiple facilities.It can be across multiple Availability Zones and this all is done to ensure availability and durability.

How data can be secured in S3?

Data can be secured by enabling 3 ways.

1) Enabling Server side encryption : Whenever new objects gets created all the new objects shall be encrypted by default.

2) Enabling Access control List (ACLs) : Specify what accounts and groups are allowed to access specific objects in a bucket.

3) Enabling Bucket Policies : What operations are allowed in a bucket. Like PUT is allowed by DELETE is not allowed.

Difference between ACLs and Bucket policies:

       ACLs are applied at individual object level in or inside bucket whereas bucket policies are applied at         bucket level.

 

Data consistency model in S3? 

      S3 supports strongly READ-after-Write consistency model in which after every update  new read will        show all new changes immediately.

      Also strong consistency for list operation wherein we can see list showing all the latest write updates.