Passing environmental variables when deploying docker to remote host - docker

Question

I am having some trouble with my docker containers and environment variables.
Currently i have a docker-compose.yml with the following defined:
version: '2.1'
services:
some-service:
build:
context: .
image: image/replacedvalues
ports:
- 8080
environment:
- PROFILE=acc
- ENVA
- ENVB
- TZ=Europe/Berlin
some-service-acc:
extends:
service: some-service
environment:
- SERVICE_NAME=some-service-acc
Now when i deploy this manually (via SSH command line directly) on server A, it will take the environmental variables from Server A and put them in my container. So i have the values of ENVA and ENVB from the host in my container. Using the following command (after building the image ofcourse): docker-compose up some-service-acc.
We are currently developing a better infrastructure and want to deploy services via Jenkins. Jenkins is up and running in a docker container on server B.
I can deploy the service via Jenkins (Job-DSL, setting DOCKER_HOST="tcp://serverA:2375"temporary). So it will run all docker (compose) commands on ServerA from the Jenkins Container on Server B. The service is up and running except that it doesn't have values for the ENVA and the ENVB.
Jenkins runs the following with the Job-DSL groovy script:
withEnv(["DOCKER_HOST=tcp://serverA:2375"]) {
sh "docker-compose pull some-service-acc"
sh "docker-compose -p some-service-acc up -d some-service-acc"
}
I tried setting them in my Jenkins container and on Server B itself but neither worked. Only when i deploy manually directly on Server A it works.
When i use docker inspect to inspect the running container, i get the following output for the env block:
"Env": [
"PROFILE=acc",
"affinity:container==JADFG09gtq340iggIN0jg53ij0gokngfs",
"TZ=Europe/Berlin",
"SERVICE_NAME=some-service-acc",
"ENVA",
"ENVB",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"LANG=C.UTF-8",
"JAVA_VERSION=8",
"JAVA_UPDATE=121",
"JAVA_BUILD=13",
"JAVA_PATH=e9e7ea248e2c4826b92b3f075a80e441",
"JAVA_HOME=/usr/lib/jvm/default-jvm",
"JAVA_OPTS="
]
Where do i need to set the Environmental variables so that they will be passed to the container? I prefer to store the variables on Server A. But if this is not possible, can someone explain me how it could be done? It is not an option to hardcode the values in the compose file or anywhere else in the source as they contain sensitive data.
If i am asking this in the wrong place, please redirect me to where i should be.
Thanks!

Answer 1

You need to set the environment variables in the shell that is running the docker-compose command line. In Jenkins, that's best done be inside your groovy script (Jenkins doesn't use the host environment within the build slave):
withEnv(["DOCKER_HOST=tcp://serverA:2375", "ENVA=hello", "ENVB=world"]) {
sh "docker-compose pull some-service-acc"
sh "docker-compose -p some-service-acc up -d some-service-acc"
}
Edit: from the comments, you also want to pass secrets.
To do that, there are plugins like the Mask Password that would allow you to pass variables without them showing up in the logs or job configuration. (I'm fairly certain a determined intruder could still get to the values since Jenkins itself knows it and passes it to your script in clear text.)
The better option IMO is to use a secrets management tool inside of docker. Hashicorp has their Vault product which implements an encrypted K/V store where values are accessed with a time limited token and offers the ability to generate new passwords per request with integration into the target system. I'd consider this the highest level of security when fully configured, but you can configure this countless ways to suit your own needs. You'll need to write something to pull the secret and inject it into your container's environment (it's a rest protocol that you can add to your entrypoint).
The latest option from Docker itself is secrets management that requires the new Swarm Mode. You save your secret in the swarm and add it to the containers you want as a file using an entry in the docker-compose.yml version 3 format. If you already use Swarm Mode and can start your containers with docker stack deploy instead of docker-compose, this is a fairly easy solution to implement.