Docker-compose using host environment variable

Question

I'm trying to do the following in my docker-compose.yml

But I hit this warning? WARNING: The HOSTNAME variable is not set. Defaulting to a blank string

environment: KAFKA_ADVERTISED_HOST_NAME: ${HOSTNAME}

The HOSTNAME environment variable is obviously set on the host.

elyas-bhy · Accepted Answer · 2016-08-01 13:52:22Z

11

You just need to export your environment variable to the docker-compose process. Try this instead:

$ export HOSTNAME
$ docker-compose up

answered Aug 1, 2016 at 13:52

elyas-bhy

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Comments

michaelbahr · Accepted Answer · 2016-02-12 11:56:38Z

4

An error saying the variable is not set looks strange indeed.

I use host variables like this:

mycontainer:
  image: <repo>/<image>:${SERVICE_VERSION}
  environment:
    - DB_USER=${DB_USER}
    - DB_PASS=${DB_PASS}

answered Feb 12, 2016 at 11:56

michaelbahr

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No I guess it must be that I'm using HOSTNAME.

Ya so just tried HOST_IP and set this on the host machine first with export HOST_IP=$(/sbin/ip route|awk '/default/ { print $3 }') this works

I guess docker is stripping out HOSTNAME env variable

Docker is automatically setting some variables: docs.docker.com/engine/reference/run/#env-environment-variables However that does not explain why the HOSTNAME is stripped during compose.yml reading.