The [AWS Command-Line Interface (CLI)](http://aws.amazon.com/cli/) can be used to return information on any/all Amazon EC2 instances, eg:

    $ aws ec2 describe-instances --instance-ids i-0c9c9b44b --query &#39;Reservations[*].Instances[*].PublicIpAddress&#39; --output text
    
    54.232.200.77

If you are seeking information about the EC2 instance from which you are executing the command, then the current IP address can be obtained via the [instance metadata service](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html#instancedata-data-retrieval):

    $ curl http://169.254.169.254/latest/meta-data/

    ami-id
    ami-launch-index
    ami-manifest-path
    block-device-mapping/
    hostname
    iam/
    instance-action
    instance-id
    instance-type
    local-hostname
    local-ipv4
    mac
    metrics/
    network/
    placement/
    profile
    public-hostname
    public-ipv4
    public-keys/
    reservation-id
    security-groups
    services/

So, the **private IP address** is available via:

    $ curl http://169.254.169.254/latest/meta-data/local-ipv4
    
    172.31.10.221

The **public IP address** is available via:

    $ curl http://169.254.169.254/latest/meta-data/public-ipv4
    
    54.232.200.77

```bash
curl http://checkip.amazonaws.com
```

this returns the public ip address.

If you are inside the instance -  
```
$ curl icanhazip.com
162.202.17.123
```
here is one more way 
```
$ curl -s ifconfig.me
162.202.17.123
```

these methods are not limited to just AWS.


From  inside instnace type following command : 
  

      curl -s v4.ident.me

Get attached InstanceID with PublicIP.

    aws ec2 describe-network-interfaces --query NetworkInterfaces[*].[Attachment.[InstanceId],Association.[PublicIp]] --output=json

I used EntityFramework Core  database first to create model [as illustrated in the EF Core documentation]
[1]

But I don&#39;t know how to update the model when the database has been edit.


  [1]: https://docs.efproject.net/en/latest/platforms/aspnetcore/existing-db.html#reverse-engineer-your-model

How to update the model when using database first approach

I am newbie in convolutional neural networks and just have idea about feature maps and how convolution is done on images to extract features. I would be glad to know some details on applying batch normalisation in CNN.

I read this paper https://arxiv.org/pdf/1502.03167v3.pdf and could understand the BN algorithm applied on a data but in the end they mentioned that a slight modification is required when applied to CNN:

&gt; For convolutional layers, we additionally want the normalization to obey the convolutional property – so that different elements of the same feature map, at different locations, are normalized in the same way. To achieve this, we jointly normalize all the activations in a mini- batch, over all locations. In Alg. 1, we let B be the set of all values in a feature map across both the elements of a mini-batch and spatial locations – so for a mini-batch of size m and feature maps of size p &#215; q, we use the effec- tive mini-batch of size m′ = |B| = m &#183; pq. We learn a pair of parameters γ(k) and β(k) per feature map, rather than per activation. Alg. 2 is modified similarly, so that during inference the BN transform applies the same linear transformation to each activation in a given feature map.


I am total confused when they say
**&quot;so that different elements of the same feature map, at different locations, are normalized in the same way&quot;**

I know what feature maps mean and different elements are the weights in every feature map. But I could not understand what location or spatial location means.

 I could not understand the below sentence at all
**&quot;In Alg. 1, we let B be the set of all values in a feature map across both the elements of a mini-batch and spatial locations&quot;**

I would be glad if someone cold elaborate and explain me in much simpler terms 

Batch Normalization in Convolutional Neural Network

Using Amazon CLI, is there a way to get the public ip address of the current EC2?  I&#39;m just looking for the single string value, so not the json response describe-addresses returns.  

Get Public IP Address on current EC2 Instance

<p>Using Amazon CLI, is there a way to get the public ip address of the current EC2?  I'm just looking for the single string value, so not the json response describe-addresses returns.</p>


What is an Internet Gateway? What is a NAT Instance? What services do they offer?

Reading AWS VPC documentation, I gather they both map private IP addresses to internet route-able addresses for the outgoing requests and route the incoming responses from the internet to the requester on the subnet. 

So what are the differences between them? What scenarios do I use a NAT Instance instead of (or besides) an Internet Gateway? 
Are they essentially EC2 instances running some network applications or are they special hardware like a router?

Instead of simply pointing to AWS documentation links, can you please explain these with adding some background on what is public and private subnets so any beginner with limited knowledge of networking can understand these easily?
Also when should I use a NAT Gateway instead of a NAT instance?

P.S. I am new to AWS VPC, so I might be comparing apples to oranges here.

AWS VPC - Internet Gateway vs. NAT

I have created a CloudFront distribution to serve the static website. S3 is origin server.
Now if we access CloudFront URL, it redirects to S3 location.

`d2s18t7gwlicql.cloudfront.net`
or
`test.telekha.in`

In the browser it is showing 
https://telekha-test-www.s3.ap-south-1.amazonaws.com/index.html#/dashboard

I am expecting https://test.telekha.in/#/dashboard

If I access https://test.telekha.in through curl it returns my `index.html` document

If I access http://test.telekha.in through curl it returns

    &lt;html&gt;
    &lt;head&gt;&lt;title&gt;301 Moved Permanently&lt;/title&gt;&lt;/head&gt;
    &lt;body bgcolor=&quot;white&quot;&gt;
    &lt;center&gt;&lt;h1&gt;301 Moved Permanently&lt;/h1&gt;&lt;/center&gt;
    &lt;hr&gt;&lt;center&gt;CloudFront&lt;/center&gt;
    &lt;/body&gt;
    &lt;/html&gt;

But in browser both HTTP and HTTPS are redirecting to https://telekha-test-www.s3.ap-south-1.amazonaws.com/index.html#/

Please let me know how to resolve this issue.



AWS CloudFront redirecting to S3 bucket

I am getting: 

&gt; An error occurred (AccessDenied) when calling the ListObjects operation: Access Denied 

When I try to get folder from my S3 bucket.

Using this command: 

    aws s3 cp s3://bucket-name/data/all-data/ . --recursive

The IAM permissions for the bucket look like this:

    {
    &quot;Version&quot;: &quot;version_id&quot;,
    &quot;Statement&quot;: [
        {
            &quot;Sid&quot;: &quot;some_id&quot;,
            &quot;Effect&quot;: &quot;Allow&quot;,
            &quot;Action&quot;: [
                &quot;s3:*&quot;
            ],
            &quot;Resource&quot;: [
                &quot;arn:aws:s3:::bucketname/*&quot;
            ]
        }
    ] }


What do I need to change to be able to `copy` and `ls` successfully?

AccessDenied for ListObjects for S3 bucket when permissions are s3:*

I am using the NodeJS AWS SDK to generate a presigned S3 URL. The docs give an [example of generating a presigned URL](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getSignedUrl-property).

Here is my exact code (with sensitive info omitted):

    const AWS = require(&#39;aws-sdk&#39;)
    
    const s3 = new AWS.S3()
    AWS.config.update({accessKeyId: &#39;id-omitted&#39;, secretAccessKey: &#39;key-omitted&#39;})
    
    // Tried with and without this. Since s3 is not region-specific, I don&#39;t
    // think it should be necessary.
    // AWS.config.update({region: &#39;us-west-2&#39;})
    
    const myBucket = &#39;bucket-name&#39;
    const myKey = &#39;file-name.pdf&#39;
    const signedUrlExpireSeconds = 60 * 5
    
    const url = s3.getSignedUrl(&#39;getObject&#39;, {
        Bucket: myBucket,
        Key: myKey,
        Expires: signedUrlExpireSeconds
    })
    
    console.log(url)

The URL that generates looks like this:

    https://bucket-name.s3-us-west-2.amazonaws.com/file-name.pdf?AWSAccessKeyId=[access-key-omitted]&amp;Expires=1470666057&amp;Signature=[signature-omitted]

I am copying that URL into my browser and getting the following response:

    &lt;Error&gt;
      &lt;Code&gt;NoSuchBucket&lt;/Code&gt;
      &lt;Message&gt;The specified bucket does not exist&lt;/Message&gt;
      &lt;BucketName&gt;[bucket-name-omitted]&lt;/BucketName&gt;
      &lt;RequestId&gt;D1A358D276305A5C&lt;/RequestId&gt;
      &lt;HostId&gt;
        bz2OxmZcEM2173kXEDbKIZrlX508qSv+CVydHz3w6FFPFwC0CtaCa/TqDQYDmHQdI1oMlc07wWk=
      &lt;/HostId&gt;
    &lt;/Error&gt;

I know the bucket exists. When I navigate to this item via the AWS Web GUI and double click on it, it opens the object with URL and works just fine:

    https://s3-us-west-2.amazonaws.com/[bucket-name-omitted]/[file-name-omitted].pdf?X-Amz-Date=20160808T141832Z&amp;X-Amz-Expires=300&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Signature=[signature-omitted]&amp;X-Amz-Credential=ASIAJKXDBR5CW3XXF5VQ/20160808/us-west-2/s3/aws4_request&amp;X-Amz-SignedHeaders=Host&amp;x-amz-security-token=[really-long-key]

So I am led to believe that I must be doing something wrong with how I&#39;m using the SDK.

Nodejs AWS SDK S3 Generate Presigned URL

I&#39;m having trouble using `*` in the AWS CLI to select a subset of files from a certain bucket.

Adding `*` to the path like this does not seem to work

`aws s3 cp s3://data/2016-08* .`


How can I use wildcards to `cp` a group of files with the AWS CLI

I&#39;m building a system consisting of an Angular2 single page app and a REST API running on ECS. The API runs on .Net/[Nancy](http://nancyfx.org/), but that might well change.

I would like to give Cognito a try and this is how I imagined the authentication workflow:

 1. SPA signs in user and receives a JWT
 2. SPA sends JWT to REST API with every request
 3. REST API verfies that the JWT is authentic

My question is about step 3. **How can my server (or rather: my stateless, auto-scaled, load-balanced Docker containers) verify that the token is authentic?** Since the &quot;server&quot; hasn&#39;t issued the JWT itself, it can&#39;t use its own secret (as described in the basic JWT example [here](https://jwt.io/introduction/)).

I have read through the Cognito docs and googled a lot, but I can&#39;t find any good guideline about what to do with the JWT on the server side.

How to verify JWT from AWS Cognito in the API backend?

I&#39;m just getting started on AWS EC2. I understand that EC2 is like a remote computer where I can do pretty much everything I want. Then I found out about ECS. I know it uses Docker, but I&#39;m confused about the relationship between these two.

Is ECS just a Docker install in EC2?
If I already have an EC2 and I start an ECS, does it mean I have two instances?


What is the difference between Amazon ECS and Amazon EC2?

Recently Amazon launched [Lightsail](https://amazonlightsail.com/). Is there any difference between them? If yes, then what&#39;s the difference? Are Lightsail instances more powerful than EC2?

What is difference between Lightsail and EC2?

I switch instances between different regions frequently and sometimes I forget to turn off my running instance from a different region. I couldn&#39;t find any way to see all the running instances on Amazon console.  
Is there any way to display all the running instances regardless of region?

How to see all running Amazon EC2 instances across all regions?

I&#39;m trying to run Elastic search in an Ubuntu EC2 machine (t2.medium).

But I&#39;m getting the message:

&gt; max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

How can I increase the `vm.max_map_count` value?



Content Type	Original Author	Original Content on Stackoverflow
Question	obautista	View Question on Stackoverflow
Solution 1 - Amazon Web-Services	John Rotenstein	View Answer on Stackoverflow
Solution 2 - Amazon Web-Services	Duke Dougal	View Answer on Stackoverflow
Solution 3 - Amazon Web-Services	markroxor	View Answer on Stackoverflow
Solution 4 - Amazon Web-Services	cryptoKTM	View Answer on Stackoverflow
Solution 5 - Amazon Web-Services	Raghvendra Soni	View Answer on Stackoverflow

Get Public IP Address on current EC2 Instance

Amazon Web-Services Problem Overview

Amazon Web-Services Solutions

Solution 1 - Amazon Web-Services

Solution 2 - Amazon Web-Services

Solution 3 - Amazon Web-Services

Solution 4 - Amazon Web-Services

Solution 5 - Amazon Web-Services

Batch Normalization in Convolutional Neural Network

How to update the model when using database first approach

Attributions