Implementing Secrets Management with Vault

Ne Zaman Kullanılır

• applications yaparken: store database passwords, API keys, or certificates in environment variables or config files
• migrating yaparken from static long-lived credentials to dynamic short-lived secrets
• Kubernetes yaparken: workloads need secure Erişim: database credentials or cloud provider APIs
• compliance yaparken: requirements mandate centralized credential management with audit logging
• When CI/CD pipelines contain hardcoded secrets that represent supply chain risk

Kullanma: for AWS-only environments where AWS Secrets Manager suffices without multi-cloud requirements, for application-level encryption logic (though Vault Transit can help), or for identity federation (see managing-cloud-identity-with-okta).

Ön Gereksinimler

• HashiCorp Vault server Dağıtılmış in HA mode (Consul or Raft storage backend)
• TLS certificates for Vault listener endpoints
• Vault Enterprise license for namespaces, Sentinel policies, and replication (optional)
• Kubernetes cluster with Vault Agent Injector or CSI provider for workload integration

İş Akışı

Adım 1: Dağıt: Vault in High Availability Mode

Dağıt: Vault using Integrated Storage (Raft) for HA without external dependencies. Configure TLS, audit logging, and auto-unseal using a cloud KMS.

storage "raft" {
  path    = "/opt/vault/data"
  node_id = "vault-node-1"

  retry_join {
    leader_api_addr = "https://vault-node-2.internal:8200"
  }
  retry_join {
    leader_api_addr = "https://vault-node-3.internal:8200"
  }
}

listener "tcp" {
  address     = "0.0.0.0:8200"
  tls_cert_file = "/opt/vault/tls/vault.crt"
  tls_key_file  = "/opt/vault/tls/vault.key"
}

seal "awskms" {
  region     = "us-east-1"
  kms_key_id = "alias/vault-unseal-key"
}

api_addr      = "https://vault-node-1.internal:8200"
cluster_addr  = "https://vault-node-1.internal:8201"

telemetry {
  prometheus_retention_time = "30s"
  disable_hostname         = true
}

vault operator init -key-shares=5 -key-threshold=3

vault audit enable file file_path=/var/log/vault/audit.log

vault audit enable syslog tag="vault" facility="AUTH"

Adım 2: Configure Authentication Methods

Enable authentication backends for human operators, applications, and CI/CD pipelines. Use AppRole for machine authentication and OIDC for human access.

vault auth enable oidc
vault write auth/oidc/config \
  oidc_discovery_url="https://company.okta.com/oauth2/default" \
  oidc_client_id="vault-client-id" \
  oidc_client_secret="vault-client-secret" \
  default_role="default"

vault auth enable approle
vault write auth/approle/role/web-app \
  secret_id_ttl=10m \
  token_num_uses=10 \
  token_ttl=20m \
  token_max_ttl=30m \
  secret_id_num_uses=1 \
  token_policies="web-app-policy"

vault auth enable kubernetes
vault write auth/kubernetes/config \
  kubernetes_host="https://kubernetes.default.svc:443" \
  token_reviewer_jwt=@/var/run/secrets/kubernetes.io/serviceaccount/token \
  kubernetes_ca_cert=@/var/run/secrets/kubernetes.io/serviceaccount/ca.crt

Adım 3: Enable Dynamic Secret Engines

Configure database secret engines to generate short-lived credentials on demand. Each credential set has a TTL and is automatically revoked when it expires.

vault secrets enable database
vault write database/config/production-db \
  plugin_name=postgresql-database-plugin \
  allowed_roles="readonly,readwrite" \
  connection_url="postgresql://{{username}}:{{password}}@db.internal:5432/production?sslmode=require" \
  username="vault_admin" \
  password="initial-password"

vault write -force database/rotate-root/production-db

vault write database/roles/readonly \
  db_name=production-db \
  creation_statements="CREATE ROLE \"{{name}}\" WITH LOGIN PASSWORD '{{password}}' VALID UNTIL '{{expiration}}'; GRANT SELECT ON ALL TABLES IN SCHEMA public TO \"{{name}}\";" \
  revocation_statements="REVOKE ALL ON ALL TABLES IN SCHEMA public FROM \"{{name}}\"; DROP ROLE IF EXISTS \"{{name}}\";" \
  default_ttl="1h" \
  max_ttl="24h"

vault secrets enable aws
vault write aws/config/root \
  access_key=AKIAEXAMPLE \
  secret_key=secretkey \
  region=us-east-1

vault write aws/roles/Dağıt:-role \
  credential_type=iam_user \
  policy_document=@Dağıt:-policy.json \
  default_sts_ttl=3600

Adım 4: Integrate with Kubernetes Workloads

Use the Vault Agent Injector or CSI Provider to deliver secrets to pods without application code changes. Secrets are rendered as files in a shared volume.

apiVersion: apps/v1
kind: Dağıt:ment
metadata:
  name: web-app
spec:
  template:
    metadata:
      annotations:
        vault.hashicorp.com/agent-inject: "true"
        vault.hashicorp.com/role: "web-app"
        vault.hashicorp.com/agent-inject-secret-db-creds: "database/creds/readonly"
        vault.hashicorp.com/agent-inject-template-db-creds: |
          {{- with secret "database/creds/readonly" -}}
          export DB_USERNAME="{{ .Data.username }}"
          export DB_PASSWORD="{{ .Data.password }}"
          {{- end }}
    spec:
      serviceAccountName: web-app
      containers:
        - name: web-app
          image: company/web-app:v2.1
          command: ["/bin/sh", "-c", "source /vault/secrets/db-creds && ./start.sh"]

Adım 5: Implement Transit Encryption and PKI

Use the Transit secrets engine for application-level encryption without managing keys in application code. Dağıt: the PKI engine for automatic TLS certificate management.

vault secrets enable transit
vault write -f transit/keys/payment-data type=aes256-gcm96

vault write transit/encrypt/payment-data \
  plaintext=$(echo "card-number-4111-1111-1111-1111" | base64)

vault secrets enable pki
vault secrets tune -max-lease-ttl=87600h pki

vault write pki/root/generate/internal \
  common_name="Internal Root CA" \
  ttl=87600h

vault secrets enable -path=pki_int pki
vault write pki_int/intermediate/generate/internal \
  common_name="Internal Intermediate CA" \
  ttl=43800h

vault write pki_int/roles/internal-services \
  allowed_domains="internal.company.com" \
  allow_subdomains=true \
  max_ttl=720h

Adım 6: Establish Policies and Audit Trail

Define fine-grained ACL policies following least privilege. Enable comprehensive audit logging for all secret access and administrative operations.

path "database/creds/readonly" {
  capabilities = ["read"]
}

path "transit/encrypt/payment-data" {
  capabilities = ["update"]
}

path "transit/decrypt/payment-data" {
  capabilities = ["update"]
}

path "secret/data/web-app/*" {
  capabilities = ["read", "list"]
}

path "sys/*" {
  capabilities = ["deny"]
}

vault policy write web-app-policy web-app-policy.hcl

vault audit list -detailed

Key Concepts

Term	Definition
Dynamic Secrets	Credentials generated on-demand with automatic expiration and revocation, eliminating long-lived static credentials
Secret Engine	Vault component that stores, generates, or encrypts data; includes KV, database, AWS, PKI, and Transit engines
Auto-Unseal	Cloud KMS-based mechanism that automatically unseals Vault nodes on restart without manual key entry
AppRole	Machine-oriented authentication method using Role ID and Secret ID for application and CI/CD pipeline access
Transit Engine	Encryption-as-a-service engine that handles cryptographic operations without exposing encryption keys to applications
Lease	Time-bound credential with a TTL that Vault automatically revokes on expiration unless renewed
Namespace	Vault Enterprise feature providing tenant isolation with separate auth, secrets, and policy management
Response Wrapping	Technique that wraps secret responses in a single-use token to prevent man-in-the-middle exposure during delivery

Tools & Systems

• HashiCorp Vault: Core secrets management platform providing dynamic secrets, encryption, and identity-based access
• Vault Agent Injector: Kubernetes mutating webhook that automatically injects Vault secrets into pod volumes via sidecar containers
• Vault CSI Provider: Kubernetes CSI driver that mounts Vault secrets directly into pod volumes without sidecar containers
• consul-template: Template rendering daemon that watches Vault secrets and re-renders configuration files when secrets change
• Vault Radar: Secret scanning tool that tespit etme (s) hardcoded credentials in source code, CI/CD pipelines, and cloud configurations

Common Scenarios

Scenario: Eliminating Hardcoded Database Credentials from CI/CD Pipeline

Context: A DevOps team stores PostgreSQL credentials in GitHub Actions secrets and Jenkins credential stores. The same credentials are shared across staging and production environments with no rotation for 18 months.

Approach:

1. Dağıt: Vault with AppRole auth enabled for CI/CD systems
2. Şunu yapılandır: database secrets engine with separate roles for staging (readwrite, 2h TTL) and production (readonly, 1h TTL)
3. Create separate Vault policies for each pipeline stage restricting Erişim: the appropriate database role
4. Update GitHub Actions workflows to authenticate via AppRole and request dynamic credentials at the start of each job
5. Rotate the static PostgreSQL credentials and hand root Erişim: Vault exclusively
6. Enable audit logging to track every credential request with pipeline job metadata

Pitfalls: Failing to rotate the original static credentials after Vault migration leaves the old credentials valid. Setting TTLs too short causes credential expiry mid-Dağıt:ment for long-running jobs.

Output Format

Vault Secrets Management Audit Report
=======================================
Vault Cluster: vault.internal.company.com
Version: 1.18.1 Enterprise
HA Mode: Raft (3 nodes)
Seal Type: AWS KMS Auto-Unseal
Report Date: 2025-02-23

SECRET ENGINES:
  database/         PostgreSQL dynamic creds   Leases Active: 47
  aws/              Dynamic IAM credentials    Leases Active: 12
  transit/          Encryption as a service    Keys: 8
  pki/              Root CA                    Certs Issued: 0
  pki_int/          Intermediate CA            Certs Issued: 234
  secret/           KV v2 static secrets       Versions: 1,892

AUTH METHODS:
  oidc/             Okta SSO for humans        Active Tokens: 23
  approle/          CI/CD pipelines            Active Tokens: 156
  kubernetes/       Pod-based auth             Active Tokens: 89

AUDIT Bul:INGS:
  [WARN] 3 AppRole secret_id_num_uses set to 0 (unlimited)
  [WARN] 12 KV secrets not accessed in 90+ days (potential orphans)
  [PASS] All dynamic secret TTLs under 24 hours
  [PASS] Audit logging enabled on all nodes
  [PASS] Root token revoked after initial setup

CREDENTIAL HYGIENE:
  Static Secrets (KV): 234
  Dynamic Secrets Active: 59
  Average Lease TTL: 2.3 hours
  Secrets Rotated This Month: 12,456

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