Purpose

Discover services in docker and update front proxy's(based on envoy) configuration

Discoverable Containers

Only containers that have CLUSTER_<port>_NAME label are discoverable, e.g.

    LABEL CLUSTER_80_NAME=serviceA

The default front proxy path will take after the name, base on the example above this would be /serviceA.

This can be overridden by adding a prefix label, e.g.

    LABEL CLUSTER_80_URLPREFIX="/api/service1"  

Building and Running it

  go build 
  ./whale_disco 

** pair it with an envoy front-proxy
** for a slightly less mickey mousy sample

Set it up as a service through aws ec2 userdata

    cat <<'EOF' >> /lib/systemd/system/whale-disco.service
    [Unit]
    Description=Whale Disco - Docker Based Discovery
    After=network.target
    StartLimitIntervalSec=0
    [Service]
    Type=simple
    Restart=always
    RestartSec=1
    User=root
    StandardOutput=file:/var/log/whale-disco/logs.log
    StandardError=file:/var/log/whale-disco/logs.log
    ExecStart=/usr/bin/whale-disco -domain=${DomainName}
    
    [Install]
    WantedBy=multi-user.target
    EOF

    systemctl start whale-disco.service

Manual testing with samples

Steps

1. Run the services
2. Build and run whale-disco
3. Run the front-proxy

Observations

1. service1 uses an /api/service1 url prefix label, so can be accessed here http://localhost:10000/api/service1 refresh the page, notice that it is alternately being served by two containers
2. service2 does not have a url prefix label, so it can be accessed here http://localhost:10000/service2/test

Notes

• EDS config dump is not available by default in the admin site, specify include_eds query parameter to make it visible, e.g http://localhost:9901/config_dump?include_eds