How to: programmatically check for existing user in mongoDb Atlas usi…

content/posts/2025-05-29-checking-for-atlas-users-before-creating/index.md

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+---
+author: "Peter Squire"
+title: "Checking for existing user in Atlas"
+description: "Check if a user exists in Atlas and create one if it doesn't"
+draft: false
+date: 2025-05-29
+tags: ["Atlas", "Ruby", "Today I Learned"]
+categories: ["Atlas", "Ruby"]
+ShowToc: true
+TocOpen: true
+---
+
+Ever had to create users in MongoDb Atlas in AWS for use when making database enquiries in a functional test written in Ruby?  
+Ever wished you could leave it to the test pack to check if one already exists and create one when required, instead of hand cranking a new one every single day of your life?  
+
+Well now you can!!!  
+
+#### But, first things first
+
+What is MongoDB Atlas and what do its users do?
+
+Atlas is a repository of database users. A user assumes a role which has database access and permissions.  
+
+Access could be to one or more databases.  
+Permissions could be read, read/write, etc.
+
+All the info you could ever want is here: https://www.mongodb.com/docs/atlas/
+
+#### Why do this? Why not create a new user every time?  
+
+Because Atlas users sit outside of a test pack and can be used for the whole time they exist.
+Plus, creating & deleting users for every test is pointless and expensive, data-wise.
+
+#### Is there anybody in there...?  
+
+Assuming you have atlas installed and configured on your machine...
+
+Let's check the existing users:
+
+In Terminal: 
+
+```ruby
+atlas dbusers list
+```
+
+This will return a list of the current users set up in the MongoDB Atlas instance you're connected to.  
+
+The list will look something like this:  
+
+USERNAME                                                                                      DATABASE
+test-repo-admin-user                                                                          admin
+mongodb-realm-triggers_realmapp-service-name-here-cluster                                     admin
+mongodb-real-service-name-here-mongodb-atlas                                                  admin
+arn:aws:iam::<ACCOUNT_NUMBER>:role/<ASSUMED_ROLE_TITLE>                                       $external
+arn:aws:iam::<OTHER_ACCOUNT_NUMBER>:role/<OTHER_ROLE_TITLE>                                   $external
+
+
+Atlas also has a method which can be used to search for a specific user  
+
+```atlas dbusers describe #{enquirier_username} --authDB \\<database> -o json```
+
+which returns a boolean value.
+
+#### Code
+
+Add this to the env.rb in your test pack.
+
+note: the 'LOG.info' commands are to output info to console. 
+
+```ruby
+
+require 'date'
+
+date_today = Date.today.strftime('%Y-%m-%d')
+account_num = ENV.fetch('AWS_ACCOUNT_NUMBER', nil)
+stage = ENV.fetch('SERVERLESS_STAGE', nil)
+service_name = ENV.fetch('SERVICE_NAME', nil)
+
+enquirier_username = "arn:aws:iam::#{account_num}:role/#{stage}-#{service_name}-<ROLE>"
+
+LOG.info { 'Checking if retrieve enquiry user exists'.cyan }
+enquirer_exist = system "atlas dbusers describe #{enquirier_username} --authDB \\$external -o json";
+
+if enquirer_exist == false
+LOG.info { 'Creating enquirer user in Atlas: '.cyan + "'#{enquirier_username}'" }
+system "atlas dbusers create readAnyDatabase -u #{enquirier_username} --awsIAMType ROLE --deleteAfter #{date_today}T23:59:59Z"
+else
+LOG.info { 'Enquiry user already created: '.cyan + "'#{enquirier_username}'" }
+end```