IAM policy for DynamoDB - Step-by-Step Execution

Concept Flow - IAM policy for DynamoDB

Define Policy Name

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Specify Effect: Allow/Deny

↓

List Actions (e.g., dynamodb:PutItem)

↓

Set Resources (Table ARNs)

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Add Conditions (optional)

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Attach Policy to User/Role/Group

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User/Role can access DynamoDB as per policy

This flow shows how to create an IAM policy for DynamoDB step-by-step, from naming to attaching it for access control.

Execution Sample

DynamoDB

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Action": ["dynamodb:PutItem", "dynamodb:GetItem"],
    "Resource": "arn:aws:dynamodb:us-east-1:123456789012:table/MyTable"
  }]
}

This policy allows PutItem and GetItem actions on a specific DynamoDB table.

Execution Table

Step	Field	Value	Effect on Access
1	Version	2012-10-17	Defines policy language version
2	Statement	Array of permissions	Groups permissions together
3	Effect	Allow	Grants permission for listed actions
4	Action	[dynamodb:PutItem, dynamodb:GetItem]	Specifies allowed DynamoDB operations
5	Resource	arn:aws:dynamodb:us-east-1:123456789012:table/MyTable	Limits actions to this table only
6	Attach Policy	User/Role/Group	Enables access as per policy
7	Access Result	User can PutItem and GetItem on MyTable	Access granted as per policy

💡 Policy fully defined and attached, user access controlled accordingly

Variable Tracker

Field	Initial	After Step 3	After Step 5	Final
Effect	None	Allow	Allow	Allow
Action	None	None	[PutItem, GetItem]	[PutItem, GetItem]
Resource	None	None	arn:aws:dynamodb:us-east-1:123456789012:table/MyTable	arn:aws:dynamodb:us-east-1:123456789012:table/MyTable

Key Moments - 3 Insights

Why do we specify the Resource ARN in the policy?

Specifying the Resource ARN limits the policy's effect to that specific DynamoDB table, preventing access to other tables. See execution_table step 5.

What happens if Effect is set to Deny instead of Allow?

Setting Effect to Deny explicitly blocks the actions listed, overriding any Allow permissions. This is shown in execution_table step 3 where Effect controls permission.

Can we list multiple actions in the Action field?

Yes, the Action field accepts an array of actions, allowing multiple DynamoDB operations in one policy, as shown in execution_table step 4.

Visual Quiz - 3 Questions

Look at the execution_table, what is the Effect value at step 3?

A Deny

B Allow

C None

D Conditional

💡 Hint

Check the 'Effect' field value in execution_table row with Step 3

At which step is the Resource ARN specified in the policy?

A Step 5

B Step 4

C Step 2

D Step 6

💡 Hint

Look for the 'Resource' field in execution_table rows

If we add 'dynamodb:DeleteItem' to the Action list, what changes in variable_tracker?

A Resource ARN changes

B Effect changes to Deny

C Action field will include DeleteItem

D No change

💡 Hint

Check how the Action field values are tracked in variable_tracker

Concept Snapshot

IAM Policy for DynamoDB:
- Define 'Version' and 'Statement'
- 'Effect' is Allow or Deny
- 'Action' lists DynamoDB operations
- 'Resource' limits to specific tables
- Attach policy to user/role for access control

Full Transcript

This visual execution shows how to create an IAM policy for DynamoDB. First, you define the policy version and group permissions in a statement. Then, set the Effect to Allow to grant access. Specify the DynamoDB actions like PutItem and GetItem. Limit the policy to a specific table using the Resource ARN. Finally, attach the policy to a user or role to enable access. The execution table tracks each step and the variable tracker shows how fields like Effect, Action, and Resource change. Key moments clarify why Resource limits access, the role of Effect, and multiple actions. The quiz tests understanding of these steps and changes.