MarathonSRV

This is a small CLI gem that retrieves Mesos slave IP addresses and port numbers for an application id and container port combination. The idea is that this side-steps the current limitations in surfacing SRV records for these BRIDGEd ports in mesos-dns.

tl;dr poor man's port/service discovery for BRIDGEd Docker Containerized Marathon applications

Usage via CLI

$ marathon-srv find \
 --marathon http://marathon.domain.tld:8080 \
 --app-id best-redis-cluster \
 --container-port 6379 \
 --username username \
 --password password
mesos-s1,tcp,31050
mesos-s2,tcp,31507
mesos-s11,tcp,31496

$ marathon-srv help find
Usage:
  marathon-srv find --container-port=CONTAINER_PORT --marathon=MARATHON

Options:
  --marathon=MARATHON              # Marathon API URL
  [--app-id=APP_ID]                # Marathon application id
  [--protocol=PROTOCOL]            
                                   # Default: tcp
  --container-port=CONTAINER_PORT  # Docker container-side port to translate
  [--username=USERNAME]            
  [--password=PASSWORD]            
  [--healthy=HEALTHY]              # Consider healthy application instances/tasks only
                                   # Default: true
  [--verbose=VERBOSE]              # Output Logger::DEBUG information to STDOUT
  [--json=JSON]                    # JSON encode response ( instead of CSV )

Returns a list of ip addresses and port numbers for an application name and service port number

Usage via Marathon::Srv::Client object

client = Marathon::Srv::Client.new "http://marathon.domain.tld:8080", "username", "password", {:log_level => Logger::DEBUG}
client.get_bridged_port_array "best-redis-cluster", true # 2nd parameter : consider healthy tasks only

Notes

Tests

Are there for the Client, not there for the CLI, and a bit spotty in general

Health checks

When considering only healthy tasks, all health checks must pass. For TCP health checks, port index is not considered - if any of the health checks fail, the task is dropped and will not contribute host/port entries.

marathon-srv