gistfile1.txt

[Unit]
Description=Mongodb service on port %i

# Requirements
Requires=etcd.service
Requires=docker.service
Requires=mongodb-discovery@%i.service

# Dependency ordering
After=etcd.service
After=docker.service
Before=mongodb-discovery@%i.service

[Service]
# Let processes take awhile to start up (for first run Docker containers)
TimeoutStartSec=0

# Change killmode from "control-group" to "none" to let Docker remove
# work correctly.
KillMode=none

# Get CoreOS environmental variables
EnvironmentFile=/etc/environment

# Pre-start and Start
## Directives with "=-" are allowed to fail without consequence
ExecStartPre=-/usr/bin/docker kill mongodb.%i
ExecStartPre=-/usr/bin/docker rm mongodb.%i
# I don't trust the "dockerfile" repository
ExecStartPre=/usr/bin/docker pull dockerfile/mongodb
ExecStart=/usr/bin/docker run --name mongodb.%i -p ${COREOS_PRIVATE_IPV4}:%i:27017 \
    dockerfile/mongodb

# Stop
ExecStop=/usr/bin/docker stop mongodb.%i


[X-Fleet]
# Don't schedule on the same machine as other Mongo instances
X-Conflicts=mongodb@*.service

gistfile2.txt

[Unit]
Description=Mongodb on port %i etcd registration

# Requirements
Requires=etcd.service
Requires=mongodb@%i.service

# Dependency ordering and binding
After=etcd.service
After=mongodb@%i.service
BindsTo=mongodb@%i.service

[Service]

# Get CoreOS environmental variables
EnvironmentFile=/etc/environment

# Start
## Test whether service is accessible and then register useful information
ExecStart=/bin/bash -c '\
  while true; do \
    netstat -lnt | grep ${COREOS_PRIVATE_IPV4}:%i; \
    if [ $? -eq 0 ]; then \
      etcdctl set /services/mongodb/${COREOS_PRIVATE_IPV4} \'${COREOS_PRIVATE_IPV4}:%i\' --ttl 30; \
    else \
      etcdctl rm /services/mongodb/${COREOS_PRIVATE_IPV4}; \
    fi; \
    sleep 20; \
  done'

# Stop
ExecStop=/usr/bin/etcdctl rm /services/mongodb/${COREOS_PRIVATE_IPV4}

[X-Fleet]
# Schedule on the same machine as the associated Mongodb service
X-ConditionMachineOf=mongodb@%i.service