learn AWS

 S3 In AWS S3 storage is special kind of storage that provides flexibility that other kind of storage services don't provide. S3 is sitting internet facing subnet and if we want to access S3 bucket from our private subnet we need to either direct traffic over internet gateway or use S3 gateway endpoint service.  To access or upload files to S3 we must use REST API for that. This actually makes things easier because thanks to this we will be able to do all operations programmatically (via our favorite programming language). In block storage service we supposed to use operating system to perform all the tasks. There should be some kind of hierarchy. But in S3 files storage in "bucket"s. Hierarchy can be mimicked by prefixes.  Let's create bucket and access over internet Search S3 in the search bar  Create a bucket Name must be unique otherwise it will display an error. Use default settings. After that try to upload some files there. Click to that file you will see the ...

OSI model consists of 7 layer : 1. Physical layer - Raw bits transfered over cable via electrical signals. 2. Data link - Switches direct these electrical signals. They use MAC address to identify the next destination.  3. Network layer - Routers receive frames from Data link layer and directs them to the destination based on the address defined in the frame. They use IP (Internet protocol) to identify the next destination. ICMP, ARP are example protocols work on this layer. 4. Transport layer - This layer manages delivery and error checking. TCP,UDP are the examples of protocols work on this layer. 5. Session layer - This layer controls communication between two computers. Netbios,PPTP is the one of the example works on this layer. 6. Presentation layer - This layer is responsible for encryption/decryption of data. SSL, TLS are examples. 7. Application layer - The final layer where user interacts. Example protocols : HTTP,SMTP, FTP etc. So we can say that switches connect computer...

Load balancing and Auto scaling Let's suppose we have deployed our web application to the EC2 instance. And all of the sudden, our app. got viral and previously 10k daily users became 1 million. So we want our infrastructure to use less resources when there is little or no user, more when there is high load or spike, it somehow must adjust itself in a way to withstand to this load. This is when auto scaling comes into play. Load balancer - is a proxy that allows you to distribute connections to servers. It provides fault tolerance and high availability . Load balancer can be front of  EC2,ECS, other load balancers, lambda functions etc. There are 3 types of load balancer in AWS: Application load balancer (operates at Application layer (L7) http, https etc.) Network load balancer (operates at IP layer (L4) -  TCP, TLS, UDP etc.)  Gateway load balancer (uses Geneva protocol, balances firewalls,IDS/IPS, operates at layer 3 ) Auto scaling - allows you to automatically and ter...

Using Roles for a Service So as we mentioned before, Role is important part of IAM since it supports security of service indirectly. Let's imagine the scenario we want EC2 instance to access our S3 bucket (object storage) and receive some files from it. Since we have to do it programmatically, need to use cli for that. But cli is not enough, we need some kind of credentials to authenticate ourselves into the service. We can use access credentials and Roles for that .   Let's list S3 buckets using the command below, but it will display and error. It couldn't find the credentials that will help it to authenticate.  Search IAM and navigate to the users page. Click to the "create access key" button. Choose "Command line interface" option. Copy the credentials and paste into the cli. Use aws-cli utility tool to add credentials. And then you will be able to list all the available buckets. The issue with this approach is that it is not recommended and secure wa...