compose/docs/env.md

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layout: default
title: Fig environment variables reference
---

Environment variables reference
===============================

Fig uses [Docker links] to expose services' containers to one another. Each linked container injects a set of environment variables, each of which begins with the uppercase name of the container.

To see what environment variables are available to a service, run `fig run SERVICE env`.

<b><i>name</i>\_PORT</b><br>
Full URL, e.g. `DB_1_PORT=tcp://172.17.0.5:5432`

<b><i>name</i>\_PORT\_<i>num</i>\_<i>protocol</i></b><br>
Full URL, e.g. `DB_1_PORT_5432_TCP=tcp://172.17.0.5:5432`

<b><i>name</i>\_PORT\_<i>num</i>\_<i>protocol</i>\_ADDR</b><br>
Container's IP address, e.g. `DB_1_PORT_5432_TCP_ADDR=172.17.0.5`

<b><i>name</i>\_PORT\_<i>num</i>\_<i>protocol</i>\_PORT</b><br>
Exposed port number, e.g. `DB_1_PORT_5432_TCP_PORT=5432`

<b><i>name</i>\_PORT\_<i>num</i>\_<i>protocol</i>\_PROTO</b><br>
Protocol (tcp or udp), e.g. `DB_1_PORT_5432_TCP_PROTO=tcp`

<b><i>name</i>\_NAME</b><br>
Fully qualified container name, e.g. `DB_1_NAME=/myapp_web_1/myapp_db_1`

[Docker links]: http://docs.docker.io/en/latest/use/port_redirection/#linking-a-container