fine-tune-client.yaml

---
- name: Fine-tune OS settings to let k6 run with large number of sockets
  hosts: all

  tasks:
    - name: Increase number of maximum open files (also sockets)
      ansible.builtin.blockinfile:
        path: ~/.bashrc
        block: |
          # Increase soft limit for open files (sockets).
          ulimit -n 100000
        marker: "# {mark} ANSIBLE ULIMIT BLOCK"
        create: yes

    - name: Fine-tune IPv4 settings in Linux kernel
      become: true
      ansible.builtin.copy:
        dest: /etc/sysctl.d/10-k6-fine-tune.conf
        owner: root
        group: root
        mode: '0644'
        content: |
          # Fine tune some kernel settings as suggested by k6 docs.
          # See: https://grafana.com/docs/k6/latest/set-up/fine-tune-os/
          net.ipv4.ip_local_port_range=7000 65000
          net.ipv4.tcp_tw_reuse=1
          net.ipv4.tcp_timestamps=1

          # Speed up socket closing by decreasing FIN_WAIT2 state timeout.
          net.ipv4.tcp_fin_timeout=5

          # Increase queue size for incoming packets (responses from the
          # server).
          net.core.netdev_max_backlog = 5000