mesos-consul

Mesos to Consul bridge for service discovery.

Mesos-consul automatically registers/deregisters services run as Mesos tasks.

This means if you have a Mesos task called application, this program will register the application in Consul, and it will be exposed via DNS as application.service.consul.

This program also does Mesos leader discovery, so that leader.mesos.service.consul will point to the current leader.

Table of Contents

• mesos-consul
  • Comparisons to other discovery software
    • [Mesos-dns](#mesos-dnshttpsgithubcommesospheremesos-dns)
    • [Registrator](#registratorhttpsgithubcomgliderlabsregistrator)
  • Building
  • Running
  • Usage
    • Options
    • Consul Registration
      • Leader, Master and Follower Nodes
      • Mesos Tasks
  • Todo

Comparisons to other discovery software

Mesos-dns

This project is similar to mesos-dns in that it polls Mesos to get information about tasks. However, instead of exposing this information via a built-in DNS server, we populate Consul service discovery with this information. Consul then exposes the services via DNS and via its API.

Benefits of using Consul:

• Integration with other tools like consul-template
• Multi-DC DNS lookups
• Configurable health checks that run on each system

Registrator

Registrator is another tool that populates Consul (and other backends like etcd) with the status of Docker containers. However, Registrator is currently limited to reporting on Docker containers and does not track Mesos tasks.

Building and running mesos-consul

Building and running in Docker

Mesos-consul can be run in a Docker container via Marathon.

To build the Docker image, do:

docker build -t mesos-consul .

To run mesos-consul, start the docker image within Mesos. If your Zookeeper and Marathon services are registered in consul, you can use .service.consul to find them, otherwise change the vaules for your environment:

curl -X POST -d@mesos-consul.json -H "Content-Type: application/json" http://marathon.service.consul:8080/v2/apps'

Where mesos-consul.json is similar to (replacing the image with your image):

{
  "args": [
    "--zk=zk://zookeeper.service.consul:2181/mesos"
  ],  
  "container": {
    "type": "DOCKER",
    "docker": {
      "network": "BRIDGE",
      "image": "{{ mesos_consul_image }}:{{ mesos_consul_image_tag }}"
    }   
  },  
  "id": "mesos-consul",
  "instances": 1,
  "cpus": 0.1,
  "mem": 256
}

You can add options to authenticate via basic http or Consul token.

Building and running as a service on the Marathon instance

If you don't want to use Docker, it is possible to compile the binary and run it on a Marathon / Mesos master server.

To build it:

• ensure that Go is installed on the build server
• make sure GOPATH is set
• clone this repository and cd into it
• run make
• the binary will be created at bin/mesos-consul
• copy this to the Marathon server and start it with mesos-consul --zk=zk://zookeeper.service.consul:2181/mesos

Usage

Options

Option	Description
version	Print mesos-consul version
log-level	Set the Logging level to one of DEBUG, INFO, WARN, ERROR. (default WARN)
refresh	Time between refreshes of Mesos tasks
mesos-ip-order	Comma separated list to control the order in which github.com/CiscoCloud/mesos-consul searches or the task IP address. Valid options are 'netinfo', 'mesos', 'docker' and 'host' (default netinfo,mesos,host)
healthcheck	Enables a http endpoint for health checks. When this flag is enabled, serves health status on 127.0.0.1:24476
healthcheck-ip	Health check service interface ip
healthcheck-port	Health check service port. (default 24476)
consul-auth	The basic authentication username (and optional password), separated by a colon.
consul-ssl	Use HTTPS while talking to the registry.
consul-ssl-verify	Verify certificates when connecting via SSL.
consul-ssl-cert	Path to an SSL certificate to use to authenticate to the registry server
consul-ssl-cacert	Path to a CA certificate file, containing one or more CA certificates to use to valid the registry server certificate
consul-token	The registry ACL token
heartbeats-before-remove	Number of times that registration needs to fail before removing task from Consul. (default: 1)
whitelist	Only register services matching the provided regex. Can be specified multitple time
blacklist	Does not register services matching the provided regex. Can be specified multitple time
service-name=<name>	Service name of the Mesos hosts
service-tags=<tag>,...	Comma delimited list of tags to register the Mesos hosts. Mesos hosts will be registered as (leader
service-id-prefix=<prefix>	Prefix to use for consul service ids registered by mesos-consul. (default: mesos-consul)
task-tag=<pattern:tag>	Tag tasks matching pattern with given tag. Can be specified multitple times
zk*	Location of the Mesos path in Zookeeper. The default value is zk://127.0.0.1:2181/mesos
log-level	Level that mesos-consul should log at. Options are [ "DEBUG", "INFO", "WARN", "ERROR" ]. Default is WARN.
group-separator	Choose the group separator. Will replace _ in task names (default is empty)

Consul Registration

Leader, Master and Follower Nodes

Role	Registration
Leader	leader.mesos.service.consul, master.mesos.service.consul
Master	master.mesos.service.consul
Follower	follower.mesos.service.consul

Mesos Tasks

Tasks are registered as task_name.service.consul

Tags

Tags can be added to consul by using labels in Mesos. If you are using Marathon you can add a label called tags to your service definition with a comma-separated list of strings that will be registered in consul as tags.

For example, in your marathon service definition:

{
  "id": "tagging-test",
  "container": { /*...*/},
  "labels": {
    "tags": "label1,label2,label3"
  }
}

This will result in a service tagging-test being created in consul with 3 separate tags: label1 label2 and label3

// GET /v1/catalog/service/tagging-test
[
  {
    Node: "consul",
    Address: "10.0.2.15",
    ServiceID: "mesos-consul:10.0.2.15:tagging-test:31562",
    ServiceName: "tagging-test5",
    ServiceTags: [
      "label1",
      "label2",
      "label3"
    ],
    ServiceAddress: "10.0.2.15",
    ServicePort: 31562
  }
]

Override Task Name

By adding a label overrideTaskName with an arbitrary value, the value is used as the service name during consul registration. Tags are preserved.

Todo

• Use task labels for metadata
• Support for multiple port tasks