OCI IAM and Identity Management - Expert Knowledge

🏗️ Use OCI Landing Zone Terraform Modules

Don't reinvent the wheel. Use oracle-terraform-modules/landing-zone for IAM structure.

Landing Zone solves:

• ❌ Bad Practice #1: Flat compartments (Landing Zone provides hierarchical structure)
• ❌ Bad Practice #2: Administrator for daily ops (Landing Zone enforces least privilege)
• ❌ Bad Practice #6: Manual IAM policies (Landing Zone provides CIS-compliant IaC)

This skill provides: IAM syntax, troubleshooting, and policy patterns for resources deployed WITHIN a Landing Zone.

⚠️ OCI CLI/API Knowledge Gap

You don't know OCI CLI commands or OCI API structure.

Your training data has limited and outdated knowledge of:

• OCI CLI syntax and parameters (updates monthly)
• OCI API endpoints and request/response formats
• IAM service CLI operations (oci iam policy, oci iam dynamic-group)
• Policy verb/resource combinations (OCI-specific, not AWS/Azure)
• Latest IAM features and Identity Domains

When OCI operations are needed:

1. Use exact CLI commands from this skill's references
2. Do NOT guess OCI IAM policy syntax
3. Do NOT assume AWS/Azure IAM patterns work in OCI
4. Load reference files for detailed IAM policy documentation

What you DO know:

• General IAM concepts (principals, policies, groups)
• Role-based access control principles
• Least privilege security concepts

This skill bridges the gap by providing current OCI-specific IAM patterns and syntax.

You are an OCI IAM expert. This skill provides knowledge Claude lacks: policy syntax gotchas, permission troubleshooting, dynamic group patterns, and OCI-specific IAM operational knowledge.

NEVER Do This

❌ NEVER use overly broad policies (security risk)

# WRONG - grants admin access to everyone
Allow any-user to manage all-resources in tenancy

# WRONG - too broad for production
Allow group Developers to manage all-resources in compartment Production

# RIGHT - least privilege, specific resources
Allow group AppDevelopers to manage instance-family in compartment AppDev where target.instance.name =~ 'dev-*'

❌ NEVER forget compartment hierarchy in policies

# WRONG - policy in child compartment can't access parent resources
Policy location: Compartment A/B/C
"Allow group X to read buckets in compartment A"  # Fails! Policy must be in A or above

# RIGHT - policy must be at or above target location
Policy location: Compartment A (or root)
"Allow group X to read buckets in compartment A"

❌ NEVER mix up principal types (causes "not authorized" errors)

# WRONG - instance is NOT a user
Allow user <instance-ocid> to read buckets in compartment X

# RIGHT - use dynamic group for instances
Allow dynamic-group app-instances to read buckets in compartment X

❌ NEVER hardcode resource OCIDs in dynamic group rules

# WRONG - not scalable, breaks when instance replaced
ALL {instance.id = 'ocid1.instance.oc1.phx.xxxxx'}

# RIGHT - use compartment or tag matching
ALL {instance.compartment.id = '<compartment-ocid>'}
ANY {instance.freeform-tags.environment = 'production'}

❌ NEVER create circular policy dependencies

# WRONG - Group A needs policy to manage Group B, but Group B policy grants access to Group A
# Creates deadlock where neither can be created first

# RIGHT - use separate administrative groups with clear hierarchy

❌ NEVER use "any-user" in production policies (security audit failure)

# WRONG - grants access to ALL users including future unknown users
Allow any-user to read buckets in tenancy

# RIGHT - explicit group membership
Allow group DataReaders to read buckets in compartment SharedData

Cost impact: $10,000+ per compliance violation finding in SOC2/HIPAA audits

IAM Permission Troubleshooting

"404 - NotAuthorizedOrNotFound"

This error means EITHER:

1. Resource doesn't exist, OR
2. User lacks permission to see if resource exists

Troubleshooting decision tree:

404 NotAuthorizedOrNotFound?
│
├─ Does resource definitely exist?
│  ├─ YES → Permission issue
│  │  └─ Check: Does user have 'inspect' or 'read' permission?
│  │     └─ Check: Is policy in correct compartment (at or above target)?
│  └─ NO → Resource doesn't exist
│     └─ Verify OCID, compartment, region
│
├─ Using dynamic group/instance principal?
│  └─ Check: Is instance in dynamic group?
│     └─ `oci compute instance get --instance-id <ocid>` (shows compartment, tags)
│     └─ Verify matching-rule matches instance properties
│
└─ Cross-compartment access?
   └─ Policy must be in compartment that CONTAINS both source and target
      OR in root compartment

"403 - NotAuthorized"

Clear permission denied. User/principal identified but lacks permission.

Common causes:

1. Missing verb: Policy has read but action needs use or manage
2. Wrong resource-type: Policy grants instance-family but trying to access volume-family
3. Condition doesn't match: Policy has where target.instance.name = 'prod-*' but instance is dev-web-1
4. Policy not in effect yet: Policies take 10-60 seconds to propagate

Verb hierarchy (each includes permissions below):

inspect < read < use < manage

Policy Syntax Gotchas

Resource Type Families (Often Confused)

Location Syntax

# Compartment (specific)
in compartment <compartment-name or ocid>

# Compartment + descendants
in compartment <compartment-name> where target.compartment.id = <ocid>

# Tenancy (root)
in tenancy

# Specific resource (rare, for delegation)
in resource <resource-ocid>

Conditions (WHERE clause)

# Tag-based conditions
where target.resource.tag.environment = 'production'
where target.resource.freeform-tags.CostCenter = 'Engineering'

# Resource name patterns
where target.instance.name =~ 'web-*'  # Regex match

# Request properties
where request.operation = 'LaunchInstance'
where request.region = 'us-phoenix-1'

# Multiple conditions
where all {target.resource.tag.env = 'prod', target.compartment.name = 'AppProd'}
where any {target.instance.shape = 'VM.Standard.E4.Flex', target.instance.shape = 'VM.Standard.A1.Flex'}

Dynamic Group Patterns

Matching Rules Best Practices

By Compartment (most common):

ALL {instance.compartment.id = '<compartment-ocid>'}

By Tag (flexible):

ANY {instance.freeform-tags.app = 'webserver'}

By Multiple Criteria (restrictive):

ALL {instance.compartment.id = '<comp-ocid>', instance.freeform-tags.environment = 'production'}

Common Mistake: Using instance.id (specific instance) instead of instance.compartment.id (all instances in compartment)

Testing Dynamic Group Membership

# 1. Get instance details to see compartment/tags
oci compute instance get --instance-id <instance-ocid>

# 2. Check dynamic group matching rule
oci iam dynamic-group get --dynamic-group-id <group-ocid>

# 3. Verify rule matches instance properties
# Example: If rule is "instance.compartment.id = X"
# Check instance's compartment_id matches X

# 4. Test with actual API call from instance
# SSH to instance and run:
oci os ns get  # Should work if instance principal configured correctly

Compartment Strategy Anti-Patterns

❌ WRONG: Flat structure (no organization)

Tenancy
├─ Application1  (mix of dev/test/prod)
├─ Application2  (mix of dev/test/prod)
└─ SharedServices

✅ RIGHT: Environment-based hierarchy

Tenancy
├─ Production
│  ├─ App1
│  └─ App2
├─ Development
│  ├─ App1
│  └─ App2
└─ SharedServices
   ├─ Networking
   └─ Security

Benefits: Clear IAM boundaries, cost reporting by environment, blast radius containment

Authentication Methods (When to Use Each)

IDCS Integration Gotchas

Federation Setup (OCI + IDCS):

• IDCS users map to OCI via federation
• Group membership in IDCS → OCI group mapping
• Critical: OCI group names must match IDCS group names exactly

Common Issues:

• User can log in to console but can't see resources → Missing OCI IAM policy for federated group
• "Invalid credentials" → IDCS federation not configured in OCI tenancy
• Group membership doesn't sync → OCI group name doesn't match IDCS group name

Progressive Loading References

OCI IAM Policies Reference (Official Oracle Documentation)

WHEN TO LOAD oci-iam-policies-reference.md:

• Need comprehensive IAM policy syntax and examples
• Writing complex policies with conditions
• Understanding service-specific verbs and permissions
• Implementing least privilege access patterns
• Troubleshooting policy evaluation order

Do NOT load for:

• Quick policy syntax examples (covered in this skill)
• Common permission patterns (decision trees above)
• Dynamic group rules (covered in this skill)

When to Use This Skill

• Writing IAM policies: syntax, verb selection, conditions
• Troubleshooting: 403/404 errors, authorization failures, permission debugging
• Dynamic groups: matching rules, testing membership, instance principals
• Compartment strategy: hierarchy design, policy placement
• IDCS integration: federation setup, group mapping, SSO troubleshooting