This document discusses using Terraform to configure Vault infrastructure as code. It begins with an overview of Vault and Terraform. It then covers important considerations for deploying Vault like authentication methods, policies, secret engines, and rotating secrets. The document shares examples of using Terraform resources to configure LDAP, AWS IAM, database credentials, and rotating secrets in Vault. It finds that some values added to Vault via Terraform are not always readable and recommends ways to continuously learn, share knowledge, and improve practices for infrastructure as code with Vault.

1. Vault configuration as code via Terraform:
stories from trenches
Andrey Devyatkin
HashiTalks 2020

3. On your production servers...

4. On your production servers...
During outage

5. On your production servers...
During outage
or
Intrusion

6. Why this presentation? What to expect?
● Not pretending to be an expert just sharing what worked/what didn’t and hopefully
save some time for some of you
● Technical details and references
● Slides will be available online - you don’t have to remember/photo/screenshot
everything

8. I’m Andrey
● Enjoying life as technology
specialist, father and endurance
athlete
● 10+ years in the industry
● Writing tools
● Fixing automation, projects and
organisations
● Meetups/conferences organizer
● Speaker
● Trainer
● Certified this and that

9. Terraform
● Infrastructure as code
● Execution plans
● Resource graph
● Change automation
● Open Source modules
● Providers for almost everything

10. Vault
● Centrally Manage Secrets to Reduce Secrets Sprawl
● Shift from static secrets to short-time dynamically
generated ones
● Avoid shared secrets thus better audit trail
● Protect Sensitive Data Across Clouds and Private
Data Centers
● Break glass procedure

11. Where do we start?
Collect requirements and clarify context

12. Questions to ask - deployment and operations
● Where to deploy? VM? Container? Baremetal?
● Patch or scratch?
● How to access? VPN? Public? Service mesh?
● How to unseal?
● How to get in initial secrets? (Ex. TLS)
● What storage is available?
● Where to stream logs?
● Where to stream telemetry?
● How to extract audit files?
● Multi-datacenter?
● One per env or one for all?

13. Look for best practices and templates
● https://registry.terraform.io/modules/hashicorp/vault/aws/0.0.9/submodules/vault
-cluster
● https://www.gruntwork.io/infrastructure-as-code-library/v0.13.3/terraform-aws-va
ult/modules/vault-cluster
● https://github.com/hashicorp/vault-helm
● https://learn.hashicorp.com/vault/operations/ops-reference-architecture

14. Vault production (min) readiness checklist
● TLS termination
● Vault HA storage - ACL and encryption
● Local storage encryption
● Auto-unseal using KMS
● Stripped down image, infra as code,
encryption, minimal exec rights
● No ssh or other kind of remote access, NACL
for outgoing traffic
● IDS
● Backups and DR
● Logs and telemetry export from the node
● Audit on, sync audit files to remote storage,
integrity check for audit files
● Sync audit files to archive
● MFA delete on for archive buckets
● Audit files parsing and anomaly detection
● Availability/performance monitoring and
alerting
More here https://learn.hashicorp.com/vault/operations/production-hardening

15. split Vault deployment/infra Terraform spec
and
Vault configuration Terraform spec

16. Vault is up and running. What is next?

17. To start configuring Vault via Terraform we need...
● Vault URL configured as VAULT_ADDR env variable
● Vault token (root token will do for the start but revoke it afterwards together with the
rest of the root tokens)
● A good idea what are you after…
More here https://www.youtube.com/watch?v=fOybhcbuxJ0 and here
https://www.terraform.io/docs/providers/vault/index.html

18. Token
Be aware of TTL and Max TTL

19. One slide Vault intro
LDAP
k8s
App
Role
AWS
...
Auth methods
Vault
token
AWS
Data
base
Secret Engines
Rabbit
MQ
PKI
Database login credentials
AWS access keys
RabbitMQ logic credentials
Certificates
Lease
Audit device
More here https://www.youtube.com/watch?v=VYfl-DpZ5wM
KV
Transit Encrypted data
Secret value
Vault
policies

20. Auth methods and policies
Boring, hard but very important

21. You probably need more than one...
● Humans - operators and developers
● Machines - CI/CD, bots, etc
● Things - Apps, Infra etc
A good idea is to use MFA for humans, limit from where
auth methods could be invoked

22. Auth -> Role -> Token with policy
Ex.
LDAP -> LDAP backend Group -> Token with
policy

23. LDAP
● Leverages existing IAM setup
● Delegates credentials validation
● Used my humans
● Would be a good idea to simplify login procedure for your users
More here https://www.vaultproject.io/docs/auth/ldap.html

24. LDAP
resource "vault_ldap_auth_backend" "ldap" {
path = "ldap"
url = "ldaps://dc-01.example.org"
userdn = "OU=Users,OU=Accounts,DC=example,DC=org"
userattr = "sAMAccountName"
upndomain = "EXAMPLE.ORG"
binddn = "${var.binddn}"
bindpass = "${var.bindpass}"
discoverdn = false
groupdn = "OU=Groups,DC=example,DC=org"
groupfilter = "(&(objectClass=group)(member:1.:={{.UserDN}}))"
}
https://www.terraform.io/docs/providers/vault/r/ldap_auth_backend.html

25. LDAP role (backend group actually)
resource "vault_ldap_auth_backend_group" "group" {
groupname = "dba"
policies = ["dba"]
backend = "${vault_ldap_auth_backend.ldap.path}"
}
https://www.terraform.io/docs/providers/vault/r/ldap_auth_backend_group.html

26. Policy
data "vault_policy_document" "example" {
rule {
path = "secret/*"
capabilities = ["create", "read", "update", "delete", "list"]
description = "allow all on secrets"
}
}
resource "vault_policy" "example" {
name = "example_policy"
policy = "${data.vault_policy_document.example.hcl}"
}
https://www.terraform.io/docs/providers/vault/d/policy_document.html

27. Policy
● You will need a policy to manage policy...
● Deny by default
● Do not have to match LDAP group name but easier for users if it
does
● Member of multiple groups gets multiple policies
More here https://learn.hashicorp.com/vault/getting-started/policies

28. Things to consider
● token_no_default_policy
● token_bound_cidrs
● token_ttl
● token_max_ttl

29. AppRole if you really have to...
● If you don’t have a better way
● Mostly used for CI
● Initial secret issue
● No good way to audit access
More here https://www.vaultproject.io/docs/auth/approle.html

30. AppRole
resource "vault_auth_backend" "approle" {
type = "approle"
}
resource "vault_approle_auth_backend_role" "example" {
backend = vault_auth_backend.approle.path
role_name = "test-role"
token_policies = ["default", "dev", "prod"]
}
https://www.terraform.io/docs/providers/vault/r/approle_auth_backend_role.html

31. AppRole

32. AppRole
resource "vault_approle_auth_backend_role_secret_id" "secret" {
backend = "approle"
role_name = "${vault_approle_auth_backend_role.role.role_name}"
}
locals {
kv = {
role_id = "${vault_approle_auth_backend_role.role.role_id}"
secret_id = "${vault_approle_auth_backend_role_secret_id.secret.secret_id}"
}}
resource "vault_generic_secret" "kv" {
path = "${vault_mount.kv.path}/approle"
data_json = "${jsonencode(local.kv)}"
}

33. Cloud IAM, K8S, etc
● Better way for non-interactive auth
● Leverages existing entities
● Delegates entity validation

34. AWS IAM
resource "vault_auth_backend" "aws" {
type = "aws"
}
resource "vault_aws_auth_backend_role" "this" {
backend = "${vault_auth_backend.aws.path}"
role = "ci-builder"
auth_type = "iam"
bound_iam_principal_arns = ["${data.aws_iam_role.ci_builder.arn}"]
token_ttl = 3600
token_max_ttl = 3600
token_policies = ["${vault_policy.ci_builder.name}"]
}
https://www.terraform.io/docs/providers/vault/r/aws_auth_backend_role.html

35. AWS IAM
resource "aws_iam_user" "ci_builder" {
name = "${module.iam_auth_for_ci_user_name.qualified_name}"
tags = "${module.tags.default}"
}
resource "aws_iam_access_key" "ci_builder" {
user = "${aws_iam_user.ci_builder.name}"
}
resource "aws_iam_user_policy" "ci_builder" {
name = "Allow-Vault-to-look-up-users-for-iam-auth"
user = "${aws_iam_user.ci_builder.name}"
policy = "${data.aws_iam_policy_document.ci_builder.json}"
}

36. AWS IAM
# https://www.vaultproject.io/docs/secrets/aws/index.html#example-iam-policy-for-vault
data "aws_iam_policy_document" "iam_auth_for_ci" {
statement {
effect = "Allow"
actions = ["iam:GetUser","iam:GetRole",]
resources = ["arn:aws:iam::${data.aws_caller_identity.i.account_id}:*"]
}
statement {
effect = "Allow"
actions = ["sts:AssumeRole"]
resources = ["arn:aws:iam::${data.aws_caller_identity.i.account_id}:role/vault-cluster*"]
}
}

37. AWS IAM
resource "vault_aws_auth_backend_client" "ci_builder" {
backend = "${vault_auth_backend.ci_builder.path}"
access_key = "${aws_iam_access_key.ci_builder.id}"
secret_key = "${aws_iam_access_key.ci_builder.secret}"
}

38. K8S
Here are more details if you are interested
https://www.youtube.com/watch?v=t6ZKhY0-_cA

39. I got token. What is next?

40. Secret Engines!
● Get dynamic creds (or static)
● Limited lifetime
● Prevents sharing
● Break glass procedure
● Audit

41. KV
Human initiated secret storage for static secrets
and
Machine initiated-readable storage for static secrets

42. AWS
resource "aws_iam_user" "user" {
name = "vault-aws-admin"
tags = "${module.tags.default}"
}
resource "aws_iam_access_key" "key" {
user = "${aws_iam_user.user.name}"
}
resource "aws_iam_user_policy" "policy" {
name = "Allow-Vault-to-create-temp-users"
user = "${aws_iam_user.user.name}"
policy = "${data.aws_iam_policy_document.document.json}"
}

43. AWS
https://www.vaultproject.io/docs/secrets/aws/index.html#example-iam-policy-for-vault
"iam:AttachUserPolicy" "iam:ListGroupsForUser"
"iam:CreateAccessKey" "iam:ListUserPolicies"
"iam:CreateUser" "iam:PutUserPolicy"
"iam:DeleteAccessKey" "iam:RemoveUserFromGroup"
"iam:DeleteUser"
"iam:DeleteUserPolicy"
"iam:DetachUserPolicy"
"iam:ListAccessKeys"
"iam:ListAttachedUserPolicies"

44. AWS
resource "vault_aws_secret_backend" "aws" {
description = "AWS secret engine so operators can get temporary keys"
path = "aws"
region = "${data.aws_region.r.name}"
access_key = "${aws_iam_access_key.key.id}"
secret_key = "${aws_iam_access_key.key.secret}"
default_lease_ttl_seconds = "28800"
max_lease_ttl_seconds = "86400"
}

45. AWS
resource "aws_iam_role" "admin" {
name = "admin"
max_session_duration = "28800"
assume_role_policy = "${data.aws_iam_policy_document.trust.json}"
tags = "${module.tags.default}"
}
resource "vault_aws_secret_backend_role" "access-aws-admin-role" {
backend = "${vault_aws_secret_backend.aws.path}"
name = "access-aws-admin-role"
role_arns = ["${aws_iam_role.admin.arn}"]
credential_type = "assumed_role"
}

46. AWS
# https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_job-functions.html
data "aws_iam_policy" "admin" {
arn = "arn:aws:iam::aws:policy/SystemAdministrator"
}
resource "aws_iam_role_policy_attachment" "admin" {
role = "${aws_iam_role.admin.name}"
policy_arn = "${data.aws_iam_policy.admin.arn}"
}

47. AWS
data "aws_iam_policy_document" "trust" {
statement {
effect = "Allow"
actions = ["sts:AssumeRole"]
principals {
type = "AWS"
identifiers = ["${aws_iam_user.user.arn}"]
}
}
}

48. AWS
Works in the same way for apps and humans!

49. AWS
Use temporary AWS creds to generate sign-in AWS console URL! No SSO needed!
https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_providers_enable-console
-custom-url.html

50. For more inspiration https://youtu.be/Y0er4UCmqiA

51. Database creds
● Creation and revocation statements are hard
● If not done right Vault won’t be able to revoke creds
● Consider RDS IAM auth where possible

52. Secrets rotation
DB_SECRET_ENGINE_MOUNTS=$(vault secrets list -format=json | jq -r '. | to_entries[] | select(.value.type |
startswith("database")) | .key')
for DB_SECRET_ENGINE_MOUNT in ${DB_SECRET_ENGINE_MOUNTS}; do
DB_CONNECTION_NAMES=$(vault list -format=json ${DB_SECRET_ENGINE_MOUNT}config | jq --raw-output .[])
for DB_CONNECTION_NAME in ${DB_CONNECTION_NAMES}; do
vault write -force ${DB_SECRET_ENGINE_MOUNT}rotate-root/${DB_CONNECTION_NAME}
done
done

53. Secrets rotation
terraform taint aws_iam_access_key.iam_auth
terraform taint aws_iam_access_key.secret_engine
terraform apply
It is possible to do the same via API but then Terraform gets confused
https://www.vaultproject.io/api-docs/secret/aws/#rotate-root-iam-credentials
Note! Keys are still in Terraform state - encrypt state storage and state itself!

54. Unexpected findings

55. KV state issue
● Terraform provider for Vault in some cases(?) does not re-read KV and newly added
values are not readable/found
● terraform state rm data-source
data "vault_generic_secret" "rundeck_auth" {
path = "secret/rundeck_auth"
}
provider "rundeck" {
url = "http://rundeck.example.com/"
auth_token = "${data.vault_generic_secret.rundeck_auth.data["auth_token"]}"
}

56. Final thoughts
● Vault introduction is a journey
● Doing it as code is the most safe way available
● Re-use and share where/when possible
● There is still some glue needed here and there
● We need to build best practices - keep learning, keep sharing

57. Thanks!
Questions?
@andrey9kin
info@andreydevyatkin.com
https://andreydevyatkin.com
https://www.linkedin.com/in/andreydevyatkin/