Customizing the etcd unit

    The etcd systemd unit can be customized by overriding the unit that ships with the default Flatcar Container Linux settings. Common use-cases for doing this are covered below.

    Use client certificates

    etcd supports client certificates as a way to provide secure communication between clients ↔ leader and internal traffic between etcd peers in the cluster. Configuring certificates for both scenarios is done through the etcd section in a Container Linux Config. Options provided here will augment the unit that ships with Flatcar Container Linux.

    Please follow the instructions on how to create self-signed certificates and private keys.

    etcd:
      # More settings are needed here for a functioning etcd daemon
      ca_file:        /path/to/CA.pem
      cert_file:      /path/to/server.crt
      key_file:       /path/to/server.key
      peer_ca_file:   /path/to/CA.pem
      peer_cert_file: /path/to/peers.crt
      peer_key_file:  /path/to/peers.key
    storage:
      files:
        - path: /path/to/CA.pem
          filesystem: root
          mode: 0644
          contents:
            inline: |
              -----BEGIN CERTIFICATE-----
              MIIFNDCCAx6gAwIBAgIBATALBgkqhkiG9w0BAQUwLTEMMAoGA1UEBhMDVVNBMRAw
              ...snip...
              EtHaxYQRy72yZrte6Ypw57xPRB8sw1DIYjr821Lw05DrLuBYcbyclg==
              -----END CERTIFICATE-----
        - path: /path/to/server.crt
          filesystem: root
          mode: 0644
          contents:
            inline: |
              -----BEGIN CERTIFICATE-----
              MIIFWTCCA0OgAwIBAgIBAjALBgkqhkiG9w0BAQUwLTEMMAoGA1UEBhMDVVNBMRAw
              DgYDVQQKEwdldGNkLWNhMQswCQYDVQQLEwJDQTAeFw0xNDA1MjEyMTQ0MjhaFw0y
              ...snip...
              rdmtCVLOyo2wz/UTzvo7UpuxRrnizBHpytE4u0KgifGp1OOKY+1Lx8XSH7jJIaZB
              a3m12FMs3AsSt7mzyZk+bH2WjZLrlUXyrvprI40=
              -----END CERTIFICATE-----
        - path: /path/to/server.key
          filesystem: root
          mode: 0644
          contents:
            inline: |
              -----BEGIN RSA PRIVATE KEY-----
              Proc-Type: 4,ENCRYPTED
              DEK-Info: DES-EDE3-CBC,069abc493cd8bda6
    
              TBX9mCqvzNMWZN6YQKR2cFxYISFreNk5Q938s5YClnCWz3B6KfwCZtjMlbdqAakj
              ...snip...
              mgVh2LBerGMbsdsTQ268sDvHKTdD9MDAunZlQIgO2zotARY02MLV/Q5erASYdCxk
              -----END RSA PRIVATE KEY-----
        - path: /path/to/peers.crt
          filesystem: root
          mode: 0644
          contents:
            inline: |
              -----BEGIN CERTIFICATE-----
              VQQLEwJDQTAeFw0xNDA1MjEyMTQ0MjhaFw0yMIIFWTCCA0OgAwIBAgIBAjALBgkq
              DgYDVQQKEwdldGNkLWNhMQswCQYDhkiG9w0BAQUwLTEMMAoGA1UEBhMDVVNBMRAw
              ...snip...
              BHpytE4u0KgifGp1OOKY+1Lx8XSH7jJIaZBrdmtCVLOyo2wz/UTzvo7UpuxRrniz
              St7mza3m12FMs3AsyZk+bH2WjZLrlUXyrvprI90=
              -----END CERTIFICATE-----
        - path: /path/to/peers.key
          filesystem: root
          mode: 0644
          contents:
            inline: |
              -----BEGIN RSA PRIVATE KEY-----
              Proc-Type: 4,ENCRYPTED
              DEK-Info: DES-EDE3-CBC,069abc493cd8bda6
    
              SFreNk5Q938s5YTBX9mCqvzNMWZN6YQKR2cFxYIClnCWz3B6KfwCZtjMlbdqAakj
              ...snip...
              DvHKTdD9MDAunZlQIgO2zotmgVh2LBerGMbsdsTQ268sARY02MLV/Q5erASYdCxk
              -----END RSA PRIVATE KEY-----