Varnish Frontend

This playbook provisions NetActuate virtual servers and configures them as Varnish caching frontends. Use this to deploy a caching layer in front of your web application for improved performance and reduced backend load.

Provisioning Playbook

---
- hosts: localhost
  connection: local
  gather_facts: false

  vars:
    api_key: "{{ lookup('env', 'NETACTUATE_API_KEY') }}"
    varnish_plan: "VR4096x2x60"
    varnish_image: "ubuntu-24.04"
    varnish_locations:
      - ashburn
      - losangeles

  tasks:
    - name: Create Varnish frontend servers
      netactuate.cloud.server:
        api_key: "{{ api_key }}"
        hostname: "varnish-{{ item }}"
        plan: "{{ varnish_plan }}"
        location: "{{ item }}"
        image: "{{ varnish_image }}"
        state: present
      loop: "{{ varnish_locations }}"
      register: varnish_servers

    - name: Add servers to in-memory inventory
      add_host:
        name: "{{ item.ip_address }}"
        groups: varnish_frontends
      loop: "{{ varnish_servers.results }}"

Configuration Playbook

---
- hosts: varnish_frontends
  become: true
  gather_facts: true

  vars:
    varnish_memory: "256m"
    backend_host: "127.0.0.1"
    backend_port: 8080

  tasks:
    - name: Install Varnish
      apt:
        name: varnish
        state: present
        update_cache: true

    - name: Configure Varnish VCL
      copy:
        dest: /etc/varnish/default.vcl
        content: |
          vcl 4.1;

          backend default {
              .host = "{{ backend_host }}";
              .port = "{{ backend_port }}";
              .connect_timeout = 5s;
              .first_byte_timeout = 30s;
              .between_bytes_timeout = 10s;
              .probe = {
                  .url = "/health";
                  .timeout = 2s;
                  .interval = 5s;
                  .window = 5;
                  .threshold = 3;
              }
          }

          sub vcl_recv {
              if (req.method == "PURGE") {
                  return (purge);
              }

              if (req.url ~ "\.(css|js|png|jpg|jpeg|gif|ico|woff2|svg)$") {
                  unset req.http.Cookie;
                  return (hash);
              }

              if (req.http.Authorization || req.http.Cookie ~ "session") {
                  return (pass);
              }
          }

          sub vcl_backend_response {
              if (beresp.ttl <= 0s || beresp.http.Set-Cookie) {
                  set beresp.uncacheable = true;
                  return (deliver);
              }

              if (bereq.url ~ "\.(css|js|png|jpg|jpeg|gif|ico|woff2|svg)$") {
                  set beresp.ttl = 7d;
              }

              set beresp.grace = 1h;
          }

          sub vcl_deliver {
              if (obj.hits > 0) {
                  set resp.http.X-Cache = "HIT";
              } else {
                  set resp.http.X-Cache = "MISS";
              }
          }
      notify: Restart Varnish

    - name: Configure Varnish service parameters
      copy:
        dest: /etc/default/varnish
        content: |
          DAEMON_OPTS="-a :80 \
            -T localhost:6082 \
            -f /etc/varnish/default.vcl \
            -S /etc/varnish/secret \
            -s malloc,{{ varnish_memory }}"

    - name: Configure systemd override for Varnish
      file:
        path: /etc/systemd/system/varnish.service.d
        state: directory

    - name: Set Varnish listen port
      copy:
        dest: /etc/systemd/system/varnish.service.d/override.conf
        content: |
          [Service]
          ExecStart=
          ExecStart=/usr/sbin/varnishd -j unix,user=vcache -F -a :80 -T localhost:6082 -f /etc/varnish/default.vcl -S /etc/varnish/secret -s malloc,{{ varnish_memory }}
      notify:
        - Reload systemd
        - Restart Varnish

    - name: Start and enable Varnish
      systemd:
        name: varnish
        state: started
        enabled: true

  handlers:
    - name: Reload systemd
      systemd:
        daemon_reload: true

    - name: Restart Varnish
      systemd:
        name: varnish
        state: restarted

Verifying the Cache

Test that Varnish is caching responses:

curl -I http://your-varnish-server/

Look for the X-Cache: HIT header on subsequent requests to confirm caching is working.

Tuning

• Increase varnish_memory for larger cache sizes. A good starting point is 75% of available RAM.
• Adjust TTL values in the VCL to match your content update frequency.
• Use varnishstat and varnishlog on the server to monitor cache performance.

Need Help?

If you need assistance deploying Varnish, visit our support page.