dnsautomationdevops

DNS and Certificate Automation for Rapid Micro-App Deployment

UUnknown

2026-02-15

9 min read

Automate DNS records and ACME TLS for micro-apps with Terraform, cert-manager, and wildcard best practices to cut provisioning time from days to minutes.

Hook: Fast micro-apps, slow ops — fix that with DNS + ACME automation

Teams that continuously spin up micro-apps face two predictable headaches: friction creating DNS records and friction issuing TLS certificates. Both slow delivery, increase toil, and create security blind spots. This article shows a pragmatic, production-ready approach to automate ACME certificate issuance (including wildcard certs), and distribution so your dev teams can provision micro-apps in minutes — not days.

Why this matters in 2026

By 2026, micro-app workflows have accelerated. Low-code, AI-assisted development and edge devices create hundreds of ephemeral apps per team. Domain and certificate automation used to be optional; now it’s the central gating factor for secure, repeatable deployment. Key trends to consider:

ACME adoption is standard for public TLS and increasingly integrated into internal PKIs and CA tooling (cert-manager, Smallstep, Vault).
DNS APIs are ubiquitous — Cloudflare, AWS Route53, Google Cloud DNS, DigitalOcean — and their API-first controls enable full automation.
Short-lived and ephemeral certs are rising: teams prefer automated rotation over long-lived secrets.
Zone delegation and multi-tenant subzones let platform teams reduce blast radius and give dev teams safe autonomy.

High-level architecture patterns

Pick a pattern that matches your scale and threat model. I’ll show three pragmatic patterns you can implement in minutes with Terraform, Ansible, k8s cert-manager, or small CLI tools.

Pattern A — Wildcard + central distribution (fastest for many micro-apps)

Delegate a subdomain like apps.example.com.
Issue a single wildcard cert (*.apps.example.com) via ACME using DNS-01.
Use that wildcard on load balancers, Ingress controllers, or edge proxies.

Pattern B — Per-app SAN or per-subdomain certs (least privilege)

Issue short-lived certs per app (app-123.apps.example.com) using ACME.
Use DNS-01 automation or HTTP-01 if apps are public and stable long enough.
Better for tighter revocation and multi-tenant separation.

Pattern C — Delegated zone per team (best for scale)

Create hosted zones per team (team-a.apps.example.com) and delegate via NS records.
Teams manage their subzone DNS and ACME requests with scoped API tokens.
Reduces central team bottlenecks and limits DNS API creds blast radius.

Design trade-offs

Wildcard certs: fast and low-op, but can be broad — a single compromise affects all apps under the wildcard.
Per-app certs: better isolation and auditable, but increases issuance overhead and may hit CA rate limits if poorly batched.
Delegation: more operational work up-front (NS records, policies) but scales best for multi-team organizations.

Step-by-step implementation: DNS delegation + wildcard ACME

The recipe below gives a practical path to implement Pattern A quickly. You’ll see Terraform for DNS delegation, and cert-manager / acme client approaches for certificate issuance and distribution.

Prerequisites

Primary domain: example.com with an authoritative DNS provider (Route53, Cloudflare, etc.).
Access to a DNS provider with API tokens (least-privilege API key).
An ACME CA that supports DNS-01 (Let's Encrypt or a private ACME server).
Infrastructure automation: Terraform and either cert-manager (Kubernetes) or an ACME client (lego, acme.sh, certbot).

1) Delegate a subdomain with Terraform (AWS Route53 example)

Create a hosted zone for the apps subdomain and add NS records in the parent zone. This isolates your micro-app namespace and lets you manage records and ACME TXT challenges without touching the root zone.

# app-zone.tf (Terraform)
resource "aws_route53_zone" "apps" {
  name = "apps.example.com"
}

resource "aws_route53_record" "delegate_apps" {
  zone_id = var.parent_zone_id # example.com zone
  name    = "apps"
  type    = "NS"
  ttl     = 300
  records = aws_route53_zone.apps.name_servers
}

2) Issue a wildcard certificate via ACME DNS-01

Use an ACME client that supports your DNS provider API token. The key is DNS-01 because Let's Encrypt and most CAs require DNS-01 for wildcard certs.

Option A: Use cert-manager (recommended in k8s). Create a ClusterIssuer with a DNS01 solver (Cloudflare/Route53 plugin) and request a Certificate resource for *.apps.example.com.
Option B: Use a CLI ACME client like lego or acme.sh on a build server. Provide the DNS API token and request a wildcard.

# cert-manager ClusterIssuer (Cloudflare example)
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt-dns
spec:
  acme:
    server: https://acme-v02.api.letsencrypt.org/directory
    email: ops@example.com
    privateKeySecretRef:
      name: letsencrypt-dns-key
    solvers:
    - dns01:
        cloudflare:
          email: ops@example.com
          apiTokenSecretRef:
            name: cloudflare-api-token
            key: api-token

3) Distribute the certificate securely

After issuance, you must deliver certificates to the edge / load balancer / Ingress. Options:

Store in a central certificate store: HashiCorp Vault or S3 (encrypted), with short rotation policies.
Use dynamic secret distribution: Vault with PKI or ACME integration to request and lease certs on-demand.
For Kubernetes: cert-manager handles Secret creation and rotation automatically; just mount the Secret into Ingress controllers.

Automating per-app records and certs with Terraform + CI

For micro-apps spawned from a pipeline (CI/CD), the typical flow is:

CI creates a DNS A/CNAME record for the new app subdomain via Terraform or a DNS API call.
CI requests a certificate via an ACME client that uses DNS-01 (or triggers cert-manager to create a Certificate resource and waits).
CI deploys the app, updates routing, and verifies TLS endpoints.

Terraform example — create subdomain and record

# create-app.tf (Route53)
resource "aws_route53_record" "app_subdomain" {
  zone_id = aws_route53_zone.apps.zone_id
  name    = "${var.app_name}"
  type    = "CNAME"
  ttl     = 60
  records = [var.app_target]
}

Then your pipeline calls an ACME client to get a cert for ${app_name}.apps.example.com.

Ansible playbook snippet — request and push certs (lego)

- name: Obtain TLS cert with lego
  hosts: localhost
  tasks:
    - name: Request certificate via lego
      command: >
        lego --email {{ acme_email }} \
             --dns cloudflare \
             --domains {{ app_subdomain }} \
             --path /tmp/lego run

    - name: Push certs to target
      copy:
        src: /tmp/lego/certificates/{{ app_subdomain }}.crt
        dest: /etc/ssl/certs/{{ app_subdomain }}.crt
      delegate_to: '{{ app_node }}'

Kubernetes-first teams: cert-manager for fully automated ACME

For teams running micro-apps on k8s, cert-manager is often the simplest, most robust choice. It supports multiple ACME solvers (DNS-01 via DNS providers, HTTP-01 via Ingress) and renews certificates automatically. Recommended pattern:

Create a ClusterIssuer per CA (Let's Encrypt staging/production) using DNS-01 solver and a scoped API token.
Deploy Certificate objects per app or use a wildcard Certificate for many apps behind a shared Ingress.
Integrate with your Ingress-controller (NGINX, Contour, Istio) to mount Secrets for TLS termination.

Wildcard strategies and best practices

One wildcard per environment (e.g., *.apps.staging.example.com, *.apps.prod.example.com). This reduces blast radius between environments.
Limit wildcard lifetime: configure shortish renew windows and automated rotation so compromised keys have short exposure.
Use DNS delegation to give teams autonomy over subdomains and limit API token scope to a single hosted zone.
Prefer DNS-01 for wildcard issuance. HTTP-01 cannot issue wildcards and can be brittle for ephemeral apps.
Consider SAN certs if you need multi-level name coverage without wildcard risks.

Security and operational hygiene

Least privilege API tokens: create tokens scoped to the specific zone or hosted subzone. Rotate tokens regularly.
Enable DNSSEC where supported to prevent on-path DNS attacks (especially for DNS-01 challenges).
Use CAA records to restrict which CAs can issue for your domain.
Audit logs: enable provider audit logs for DNS and certificate issuance events (CloudTrail, Cloudflare logs).
Monitor rate limits: CA rate limits still matter for high churn. Batch issuance and reuse wildcard when appropriate; consider caching and batching strategies in your pipeline.

Troubleshooting common pitfalls

DNS propagation delays

DNS-01 requires your TXT record to be resolvable. Use low TTL for delegated zones and confirm the TXT record with dig before requesting issuance. For global CDNs, consider a distributed DNS solution with fast propagation; read more on caching strategies and global distribution.

CA rate limits

Avoid issuing many near-identical certificates in quick succession. If you hit limits, use a wildcard to cover many names and design your CI to cache issued certs until they near expiry.

Secrets sprawl

Storing private keys across nodes invites risk. Prefer central secret stores (Vault) or k8s Secrets with RBAC, and ensure automated rotation pipelines. See vendor guidance like trust and vendor scoring when choosing a secrets platform.

2026 advanced strategies and predictions

Looking ahead, platform teams should prepare for these trends:

Internal ACME adoption: internal PKIs exposing ACME endpoints will be standard; teams will use ACME both for public and internal cert issuance.
Ephemeral short-lived certs: more orchestration systems will issue certificates valid for hours via automated rotation, reducing the need for long-lived keys.
Edge-first TLS: edge proxies will increasingly terminate TLS with centrally managed wildcard certs to offload cert management from app nodes.
Policy-as-code for cert issuance: SLSA-style attestations and automated policy-as-code checks in CI will gate certificate creation for production namespaces.

Real-world example: 5-minute path to a wildcard cert

Delegate apps.example.com to a Route53 hosted zone using the Terraform snippet above.
Create a Route53 API token scoped to the apps.example.com zone.
Configure cert-manager ClusterIssuer with that token.
Create a Certificate resource for *.apps.example.com; cert-manager completes DNS-01 and stores the Secret.
Attach the Secret to your Ingress and validate HTTPS for test-app.apps.example.com.

That sequence can be fully codified in IaC and CI, giving developers self-service provisioning with auditability.

Actionable checklist — implement in your platform this week

Delegate a subdomain to isolate micro-app DNS.
Choose a single automation path: cert-manager (k8s) or CLI ACME + CI.
Create least-privilege DNS API tokens and store them in a secret store.
Implement a wildcard strategy for fast mass-provisioning, and a per-app fallback for sensitive services.
Instrument logs and alerts for issuance failures and impending cert expirations.

Closing — move from slow ops to immediate provisioning

Automating DNS records and ACME certificates is no longer a nice-to-have. In 2026 the velocity of micro-app creation requires reliable, auditable, and secure cert provisioning. Use delegation, least-privilege DNS API tokens, DNS-01 for wildcards, and tools like Terraform and cert-manager to build self-service platforms that keep security and uptime first.

Next step: If you want a ready-made Terraform + cert-manager starter that implements the patterns in this article, download our open-source repo (includes Route53 & Cloudflare examples, CI pipelines, and Ansible playbooks). Reach out to whata.cloud for a workshop to automate your first 100 micro-app TLS enrollments.

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