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nixy - nginx auto configuration and service discovery for Mesos/Marathon
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Nixy is a daemon that automatically configures Nginx for web services deployed on Apache Mesos and Marathon.


  • Reverse proxy and load balancer for your microservices running inside Mesos and Marathon
  • Single binary with no other dependencies (except Nginx/Openresty)
  • Written in Go to be blazingly fast and concurrent.
  • All the features you would expect from Nginx:
    • HTTP/TCP/UDP load balancing, HTTP/2 termination, websockets, SSL/TLS termination, caching/compression, authentication, media streaming, static file serving, etc.
  • Zero downtime with Nginx fall-back mechanism for sick backends and hot config reload.
  • Easy to customize your needs with templating.
  • Statistics via statsd (successful/failed updates, timings).
  • Real-time updates via Marathon's event stream (Marathon v0.9.0), so no need for callbacks.
  • Support for Marathon HA cluster, auto detects sick endpoints.
  • Automatic service discovery of all running tasks inside Mesos/Marathon, including their health status.
  • Basic auth support.
  • Health checks for errors in template, nginx config or Marathon endpoints.
  • Built-in Prometheus exporter for metrics and alerts.
  • ....


  • All versions of Marathon >= v0.9.0
  • All versions of Nginx or OpenResty (Also possible to run inside Docker).

Getting started

  1. Install nixy from pre-compiled packages. Check releases page.

  2. Edit config (default on ubuntu is /etc/nixy.toml):

    # Nixy listening port
    port = "6000"
    # X-Proxy header, defaults to hostname
    xproxy = ""
    # Marathon API
    marathon = ["http://example01:8080", "http://example02:8080"] # add all HA cluster nodes in priority order.
    user = "" # leave empty if no auth is required.
    pass = ""
    # Nixy realm, set this if you want to be able to filter your apps (e.g. when you have different loadbalancers which should expose different apps)
    # You will also need to set "NIXY_REALM" label at your app to be included in generated conf
    realm = ""
    # Nginx
    nginx_config = "/etc/nginx/nginx.conf"
    nginx_template = "/etc/nginx/nginx.tmpl"
    nginx_cmd = "nginx" # optionally "openresty" or "docker exec nginx nginx"
    nginx_ignore_check = false # optionally disable nginx config test. Health check will always show OK.
    #left_delimiter = "{{" # if you want to change the default template delimiters
    #right_delimiter = "}}" # if you want to change the default template delimiters
    # Statsd settings
    addr = "localhost:8125" # optional for statistics
    #namespace = "nixy.my_mesos_cluster"
    #sample_rate = 100
  3. Optionally edit the nginx template (default on ubuntu is /etc/nginx/nginx.tmpl)

  4. Install nginx or openresty and start the service.

    • Or if you prefer running inside Docker: "docker run -d --name nginx -p 7000:7000 -v /etc/nginx:/etc/nginx nginx". You will also need to change config "nginx_cmd" to "docker exec nginx nginx" for reloads to work correctly in this case.
  5. Start nixy! (service nixy start)

Using Nixy

Routing is based on the HTTP Host header matching app ID by default.

If apps are organized under a directory structure the directory will become the root subdomain.

This is easy to change and customize to your own choosing by editing the nginx.tmpl file. For example if you prefer routing based on uri instead of subdomains take a look at nginx-path.tmpl.

Example to access your apps /bar1, /bar2, /foo/bar3 running inside Mesos and Marathon:

curl -i localhost/ -H 'Host:'
curl -i localhost/ -H 'Host:'
curl -i localhost/ -H 'Host:'

Assuming you have configured nginx on port 80.

To set a custom subdomain for an application

Deploy your app to Marathon setting a custom label called subdomain:

"labels": {
    "subdomain": "foobar"

This will override the Host for that app and replace it with foobar as the new subdomain/host.

It's also possible to add multiple subdomains to a single app, dividing by a space character.

"labels": {
    "subdomain": "foo bar"

This will now match both foo and bar as the new subdomain/host.


Nixy uses the standard Go (Golang) template package to generate its config. It's a powerful and easy to use language to fully customize the nginx config. The default template is meant to be a working base that adds some sane defaults for Nginx. If needed just extend it or modify to suite your environment the best.

If you are unsure of what variables you can use inside your template just do a GET /v1/config and you will receive a JSON response of everything available. All labels and environment variables are available. Other options could be to enable websockets, HTTP/2, SSL/TLS, or to control ports, logging, load balancing method, or any other custom settings your applications need.

HTTP Load Balancing / Proxy


Add some ACL rules to block traffic from outside the internal network? Add a Label called internal to your app and the following snippet to your template:

{{- if $app.Labels.internal}}
# allow anyone from local network.
# block everyone else
deny all;
{{- end }}

Optionally, add dynamically which network that have access to the same label:

{{- if $app.Labels.internal}}
# allow anyone from local network.
allow {{ $app.Labels.internal }};
# block everyone else
deny all;
{{- end }}

Add a custom http header based on an Environment variable inside your app?

{{- if $app.Env.APP_ENV}}
# could be dev, stage, production...
add_header X-Environment {{ $app.Env.APP_ENV }} always;
{{- end}}

Additional template methods


Wrapper for strings.Contains. Contains reports whether substr is within string.

{{if contains $host "www" }}

Wrapper for strings.HasPrefix. HasPrefix tests whether the string s begins with prefix.

{{if hasPrefix $host "www" }}

Wrapper for strings.HasSuffix. HasSuffix tests whether the string s ends with suffix.

{{if hasSuffix $host ".com" }}

Wrapper for strings.Split. Splits the input string on the separating string and returns a slice of substrings.

{{- $url := split "localhost:8080" ":" }}
    host: {{index $url 0}}
    port: {{index $url 1}}

Alias for the strings.Join function.

apps: {{join $applist ","}}

Alias for the strings.Trim function.

host: {{trim "" "."}}

Alias for the strings.Replace function.

{{$host := "app/test/com"}}
host = {{replace $host "/" "." -1}}

Wrapper for os.Getenv. Retrieves the value of the environment variable named by the key. It returns the value, which will be empty if the variable is not present.

hostname: {{getenv "HOSTNAME"}}

Alias for time.Now

# Generated by nixy {{datetime}}


Sometimes it is useful to implement the same service with apps within marathon. In this case you can use .MergeAppsByLabel("some-label") instead of .Apps in your template to merge multiple apps into a single service.

For example if the following apps running in marathon implement the same API:

my-service-a my-service-b

And they both have the label servicename=my-service you could use MergeAppsByLabel("servicename") to access both implementations as nixy.marathon.mesos:12345.

  • When the apps are merged, Labels from each original app are added to each Task from that original app. This is necessary if you want to have implementation specific labels. For example, if one implementation is faster, we could route more traffic there.

TCP/UDP Load Balancing / Proxy

It is possible to use Nixy to configure nginx as a proxy for TCP or UDP traffic.

Please check the nginx-stream.tmpl example template. It assumes you have configured PortDefinitions correctly for all your services in Marathon.

Latest versions of Nginx open-source comes with streaming by default. If you are running version 1.9 you will need to compile it with --with-stream manually.

Nixy API

  • GET / prints nixy version.
  • GET /v1/config JSON response with all variables available inside the template.
  • GET /v1/reload manually trigger a new config reload.
  • GET /v1/health JSON response with health status of template, nginx config and Marathon endpoints available.
  • GET /v1/metrics Prometheus metrics endpoint.

Nagios Monitoring

In case you want to monitor nixy using Nagios (or compatible monitoring) you can use the included check_nixy plugin.

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