kienbui1995/skills/cloud/gcp/cloud-iam

Cloud IAM

When to Use

• Designing access control for GCP resources
• Configuring service accounts and Workload Identity Federation
• Setting org policies for compliance
• Preparing for GCP Professional Cloud Security or DevOps Engineer exam

Core Jobs

1. IAM Role Types

| Type | Description | Example | |------|-------------|---------| | Basic | Project-wide: Owner, Editor, Viewer | roles/editor | | Predefined | Service-specific, fine-grained | roles/bigquery.dataViewer | | Custom | User-defined combination of permissions | custom/myRole |

• Always prefer predefined over basic; use custom only when predefined is too broad

2. Service Account Best Practices

• One service account per workload (not shared across services)
• Grant only required roles (least privilege)
• No service account keys if possible — use Workload Identity instead
• Rotate keys every 90 days if keys are required
• Disable unused service accounts

3. Resource Hierarchy + IAM Inheritance

• Organization → Folder → Project → Resource
• IAM policies are inherited down the hierarchy
• Lower levels can only ADD permissions, not remove inherited ones
• Grant at lowest level possible (project or resource, not org)
• Use folders to group projects by team/environment

4. Org Policies

• Org Policy Service — enforces guardrails across all projects in org
• Common policies: constraints/compute.requireShieldedVm, constraints/iam.disableServiceAccountKeyCreation
• Policies applied at org/folder/project level; inherited by children

5. Workload Identity Federation

• Allow external identities (AWS, GitHub Actions, Azure AD) to access GCP without keys
• External token → exchanged for short-lived GCP credentials via STS
• Eliminates need for long-lived service account keys for CI/CD and cross-cloud

6. IAM Conditions

• Add attribute-based conditions to IAM bindings
• Examples: request.time < timestamp, resource.name.startsWith("projects/prod")
• Use for time-bound access, environment-specific access

Key Concepts

• Principal — who (user, service account, group, domain, allUsers)
• Permission — what action (bigquery.tables.get)
• Role — collection of permissions
• Policy binding — {principal: role} attached to a resource
• Deny policy — explicitly denies (overrides allow)

Checklist

• [ ] Least privilege applied (predefined > basic roles)?
• [ ] Service accounts are per-workload (not shared)?
• [ ] No service account keys (use Workload Identity or metadata server)?
• [ ] IAM conditions used for time-bound or environment access?
• [ ] Org policies enforce guardrails at org/folder level?
• [ ] IAM audit logs (Cloud Audit Logs) enabled?

Output Format

• 🔴 Critical — roles/owner or roles/editor on service accounts, service account keys committed to code
• 🟡 Warning — shared service accounts across services, no org policies for guardrails
• 🟢 Suggestion — Workload Identity Federation instead of SA keys for CI/CD

Exam Tips

• Basic roles (Owner/Editor/Viewer) → avoid; use predefined for least privilege
• Service account keys = high risk; prefer Workload Identity or metadata server credentials
• IAM is inherited from parent → grant at lowest appropriate level
• Deny policies = explicitly deny overrides all allows (use for guaranteed denial)
• Org Policy ≠ IAM; Org Policy = what CAN be done (guardrails); IAM = who CAN do it
• allUsers / allAuthenticatedUsers = public access; audit carefully