AWS API Usage in Elisp

Here's some sample elisp code for signing Amazon Web Services (AWS) API requests. The value (first element) returned by (aws-sign4) is used in Authorization header while making a request. When the function is called with an expires value, it returns a URL which can be directly used in a browser.

(require 'aws-sign4)
 
(let ((*aws-credentials*
       (lambda ()
         (values "AKIAIOSFODNN7EXAMPLE" "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"))))
  (aws-sign4 :region "eu-west-1"
             :service "s3"
             :host "s3-eu-west-1.amazonaws.com"
             :path "/some-bucket/some-file"
             ))
 
(let ((*aws-credentials*
       (lambda ()
         (values "AKIAIOSFODNN7EXAMPLE" "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"))))
  (aws-sign4 :region "us-east-1"
             :service "iam"
             :host "iam.amazonaws.com"
             :params '(("Action" . "CreateUser")
               ("UserName" . "NewUser")
               ("Version" . "2010-05-08"))
             :expires 30))
 
;; Convenience function
;; aws-url-retrieve (url &optional auth-header region payload headers service method) 
;; Simple GET URL (default region: "us-east-1")
(aws-url-retrieve "https://iam.amazonaws.com?Action=CreateUser&UserName=NewUser&Version=2010-05-08")
 
;; GET URL with authentication header
(aws-url-retrieve "https://s3.amazonaws.com/" t nil nil `(,(cons "x-amz-content-sha256" (hash ""))))
 
;; DELETE s3 bucket test-axe in region us-east-1
(aws-url-retrieve "https://test-axe.s3.us-east-1.amazonaws.com/" t nil nil
          `(,(cons "x-amz-content-sha256" (hash "")))
          "s3"
          "DELETE")
 
;; POST URL - DynamoDB create table
(aws-url-retrieve "https://dynamodb.us-west-2.amazonaws.com/" t "us-west-2"
          (concat
           "{\"KeySchema\": [{\"KeyType\": \"HASH\",\"AttributeName\": \"Id\"}],"
           "\"TableName\": \"TestTable\",\"AttributeDefinitions\": [{\"AttributeName\": \"Id\",\"AttributeType\": \"S\"}],"
           "\"ProvisionedThroughput\": {\"WriteCapacityUnits\": 5,\"ReadCapacityUnits\": 5}}")
          `(,(cons "content-type" "application/x-amz-json-1.0")
            ,(cons "x-amz-target" "DynamoDB_20120810.CreateTable")
            ))
 
;; POST URL - DynamoDB delete table
(aws-url-retrieve "https://dynamodb.us-west-2.amazonaws.com/" t "us-west-2"
          (concat
           "{\"TableName\": \"TestTable\"}")
          `(,(cons "content-type" "application/x-amz-json-1.0")
            ,(cons "x-amz-target" "DynamoDB_20120810.DeleteTable")
            ))


Code

 

Key points

  • Requests are signed using a timestamp e.g. "20221018T072146Z". A timestamp older than 5 minutes is considered invalid. For testing, you might want to use a hard-coded timestamp using :request-date.
  • Each AWS service might need a different set of mandatory headers. Look up the documentation for the same.
     

List S3 buckets using AXE
 

References

Comments

Post a Comment

Popular posts from this blog

GNU Emacs as a Comic Book Reader

Image
  Comics are available in digital format as a collection of images in a compressed ZIP or RAR file (.cbz or .cbr file extension respectively). These can be enjoyed in GNU Emacs with full access to image viewing capabilities using keybindings.   # Make sure you have unrar installed for CBR files # apt install unrar   (require 'arc2-mode)   (setq archive-summarize-files-fn 'archive-summarize-files-as-thumb)     Note: The archive-mode is capable of displaying the list of files in an archive; though it depends on external tools for extraction. For JPG and PNG, Emacs can resize the image without external convertor (ie. imagemagick). However, some menu options for image transformations in image-mode might not be available. Use the following patch for image-mode.el . @@ -460,16 +460,16 @@ image-mode-map       :help "Show image as hex"]      "--"      ["Fit to Window Height" image-transform-fit-to-...
Read more

Mozilla Readability in GNU Emacs

Image
  Output using Readability (left) and original eww (right)   Mozilla Readability is a standalone version of the readability library used for Firefox Reader View . A simple hack to eww can bring the same feature in GNU Emacs. ( Note: eww already has a readable mode. This is just an alternative. Updated the post to reflect the same.)   - Install NodeJS   - Install npm modules. npm install @mozilla/readability jsdom   - Create a file readability.js with following content. Note the file location. var { Readability } = require('@mozilla/readability'); var { JSDOM } = require('jsdom'); var fs = require("fs"); var str = fs.readFileSync(process.stdin.fd).toString(); var doc = new JSDOM(str); var reader = new Readability(doc.window.document); var article = reader.parse(); console.log(article.content);     - Modify the following function to use the file location noted above . Evaluate the function. (defun mozilla-readability (start end)   (shell-command-o...
Read more

Data Visualization with GNU Emacs

Image
    GNU Emacs can be used for quick data visualization in combination with Gnuplot. When you have some data and you want to visualize what the correlation looks like, this command comes in handy. No need for any setup - no data file and no Gnuplot script. The command below uses some sensible defaults for trivial cases. If the first line contains string label, the same is used as a key label for the value and/or axes' names as appropriate. If there's a single column of data, it is used as Y value. If there's more than one column, first column is used as X value and other columns are plotted along Y-axis. Takes care of comma or whitespace separator. Note: The latest version of the code is available at the end of the post. Options available in latest version   - Install gnuplot executable and gnuplot Elisp package . - Evaluate the defun ( C-M-x ). - Select a data range using rectangle command copy-rectangle-as-kill (C-x r M-w). - Run M-x  gnuplot-rectangle. This open...
Read more