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Simple daemon to make BGP announces if service is alive

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anycastd

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anycastd is aimed to bring new age approaches to classic applications by allowing to announce virtual addresses via BGP w/ service-level checks.

Let's imaging you gonna create your own DNS/HTTP/whatever else service so how to utilize L3 load balancing and remove announce when something goes wrong on particular node? anycastd is exactly for that! No bunch of dedicated services and stateful control on BGP routes and no semi-tested Python scripts anymore!

Usage

anycastd is written as a pretty compact daemon like application so it could run in two main ways: via systemd or via docker/podman/any other container engine so that's why there's a container image in packages is available in parallel with traditional Go binaries.

For monitoring purposes anycastd listens HTTP socket with Prometheus metrics endpoint so once routes are removed from the announce SRE's could go and check why that happened.

Configuration

anycastd longs to follow 12factor principles however it's not always possible to encode complex data structures into environment variable. So configuration is divided into two ways:

Environment

anycastd allows to set the following options via environment variables:

  • CONFIG_PATH (string, default: /config.yaml) - path to the configuration file
  • LOG_LEVEL (ENUM, default: WARN) - logging verbosity level, could one of the:
    • TRACE
    • DEBUG
    • INFO
    • WARNING
    • ERROR
    • FATAL
    • PANIC

Configuration file

Configuration file contains service configuration, i.e. how to announce, where to announce, checks to perform before announce. JSON and YAML formats for the same data structure is supported. Example:

---
announcer:
  router_id: 10.3.3.3
  local_address: 10.0.0.1
  local_asn: 65999
  routes:
    - 10.0.0.128/32
  peers:
    - name: some_router_1
      remote_address: 10.0.0.252
      remote_asn: 65000
    - name: some_router_2
      remote_address: 10.0.0.253
      remote_asn: 65000
services:
  - name: http
    check_interval: 10s
    checks:
      - kind: dns_lookup
        spec:
          query: google.com
          resolver: 127.0.0.1:53
          tries: 3
          interval: 100ms
          timeout: 3s
      - kind: http_2xx
        spec:
          url: http://127.0.0.1:8080
          method: GET
          headers:
            Host: example.com
          payload: ping
          path: /
          tries: 3
          interval: 100ms
          timeout: 2s
      - kind: tls_certificate
        spec:
          local:
            path: /etc/ssl/pki/cert.pem
          common_name: Test certificate
          dns_names:
            - site.example.org
          ip_addresses:
            - 127.0.0.1
          issuer: Test Issuer
      - kind: assigned_address
        spec:
          interface: dummy0
          ipv4: 33.22.11.0
      - kind: icmp_ping
        spec:
          static:
            host: google.com
          tries: 3
          interval: 100ms
          timeout: 5s
      - kind: tftp_rrq
        spec:
          url: tftp://127.0.0.1:69/lpxelinux.0
          tries: 3
          interval: 100ms
          timeout: 5s
metrics:
  enabled: true
  address: 127.0.0.1:9090

Available checks

Check (implemented via Checker interface) is core concept in anycastd, allows to write well-tested piece of code to enable or disable announce. In anycastd most of checks could be written without any shell invocations i.e. in pure Go which is a preferable way. That's why there's no exec command check ;)

For now the following checks are available:

  • assigned_address - ensures the address is assigned on interface
  • dns_lookup - performs DNS lookup
  • http_2xx - performs HTTP check and expects 2xx code
  • icmp_ping - performs ICMP ping to the specified host
  • tftp_rrq - performs TFTP GET request to specified URL
  • tls_certificate - performs TLS certificate validation & provide expiration date via metrics

Metrics

A special part of anycastd is a Prometheus-compatible metrics allows monitoring systems to notify operators about any changes in their service.

For now anycastd provides the following metrics:

Service

Service could provide their metrics in order to aggregate current statuses.

Metric name Labels Description
anycastd_service_up service, check Service liveness status based on checks

Checks

Check running engine provides the following metrics.

Metric name Labels Description
anycastd_check_duration_seconds service, check Duration of check execution in seconds

In addition some checkers could provide their own metrics the list of them is bellow:

tls_certificate check

Metric name Labels Description
certificate_expires_in_seconds check, path Time the certificate expires in (in seconds)

icmp_ping check

Metric name Labels Description
anycastd_check_avg_rtt_seconds check, host Avg RTT of ICMP checks
anycastd_check_loss_percent check, host Percent of packet loss
anycastd_check_max_rtt_seconds check, host Max RTT of ICMP checks
anycastd_check_min_rtt_seconds check, host Min RTT of ICMP checks
anycastd_check_packets_received_duplicates_total check, host Total amount of duplicate packets received
anycastd_check_packets_received_total check, host Total amount of packets received
anycastd_check_packets_sent_total check, host Total amount of packets sent
anycastd_check_std_dev_rtt_seconds check, host Standard deviation RTT of ICMP checks

GoBGP

The core of anycastd for BGP communication is GoBGP which allows so gather some details about peers, sessions and announces.

Metric name Labels Description
anycastd_gobgp_peer_admin_state router_id, peer Peer state 0=up, 1=down, 2=pfx_ct
anycastd_gobgp_peer_count router_id Total amount of peers configured for the GoBGP instance
anycastd_gobgp_peer_flops_count router_id, peer Peer flops count
anycastd_gobgp_peer_out_queue_count router_id, peer Peer outgoing messages queue
anycastd_gobgp_peer_password_set_flag router_id, peer Whether the peer have peer password set flag set
anycastd_gobgp_peer_remove_private_flag router_id, peer Whether the peer have remove private flag set
anycastd_gobgp_peer_send_community_flag router_id, peer Whether the peer have send community flag set
anycastd_gobgp_peer_session_state router_id, peer Peer session state 0=unknown, 1=idle, 2=connect, 3=active, 4=opensent, 5=openconfirm, 6=established
anycastd_gobgp_peer_type router_id, peer Peer type 0=internal, 1=external
anycastd_gobgp_received_messages_keepalive router_id, peer Number of Keepalive messages received from the peer
anycastd_gobgp_received_messages_notification router_id, peer Number of Notification messages received from the peer
anycastd_gobgp_received_messages_open router_id, peer Number of Open messages received from the peer
anycastd_gobgp_received_messages_refresh router_id, peer Number of Refresh messages received from the peer
anycastd_gobgp_received_messages_total router_id, peer Total number of messages received from the peer
anycastd_gobgp_received_messages_update router_id, peer Number of Update messages received from the peer
anycastd_gobgp_received_messages_withdraw_update router_id, peer Number of Withdraw Update messages received from the peer
anycastd_gobgp_sent_messages_keepalive router_id, peer Number of Keepalive messages sent to the peer
anycastd_gobgp_sent_messages_notification router_id, peer Number of Notification messages sent to the peer
anycastd_gobgp_sent_messages_open router_id, peer Number of Open messages sent to the peer
anycastd_gobgp_sent_messages_refresh router_id, peer Number of Refresh messages sent to the peer
anycastd_gobgp_sent_messages_total router_id, peer Total number of messages sent to the peer
anycastd_gobgp_sent_messages_update router_id, peer Number of Update messages sent to the peer
anycastd_gobgp_sent_messages_withdraw_prefix router_id, peer Number of Withdraw Prefix messages sent to the peer
anycastd_gobgp_sent_messages_withdraw_update router_id, peer Number of Withdraw Update messages sent to the peer

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