Define environment variables for deployed containers

[robhaswell]

Docker convention is to supply runtime configuration to containers as environment variables. A user must be able to define the environment for each container in the Flocker configuration.

• GearClient should allow units to be configured with environment variables #568 GearClient.add environment variables
• Application configuration YAML should support Applications with environment variables #569 Environment variables in application.yml
• Add environment variable support to flocker.node.Deployer.calculate_necessary_state_changes #586 Add environment variable support to flocker.node.Deployer.calculate_necessary_state_changes
• Documentation for applications with environment variables #593 Documentation for applications with environment variables

[exarkun]

This is probably part of the application configuration. Along with the volume and image information, we should include a section for environment variables and their values.

[itamarst]

We can probably do the demonstrations we want for 0.1 without this feature.

[itamarst]

Latest gear supports this I think, but we may need to update the gear we've packaged.

[wallrj]

It seems that our versions of gear and docker do allow us to supply environment variables.

[vagrant@localhost environment-server]$ sudo gear install --start=true clusterhq/environment-server:1 rjw1 foo=bar deep=purple firstname=richard
Setting --env-id to N4bFpLmjQwT4iZqCa5mIwA
systemd: Reloading daemon
Container rjw1 is starting

[vagrant@localhost environment-server]$ sudo gear status rjw1
ctr-rjw1.service - Container rjw1
   Loaded: loaded (/var/lib/containers/units/rj/ctr-rjw1.service; enabled)
   Active: active (running) since Thu 2014-08-14 02:36:25 PDT; 8s ago
  Process: 3830 ExecStartPost=/usr/bin/gear init --post rjw1 clusterhq/environment-server:1 (code=exited, status=0/SUCCESS)
  Process: 3821 ExecStartPre=/usr/bin/docker rm rjw1 (code=exited, status=1/FAILURE)
  Process: 3811 ExecStartPre=/bin/sh -c /usr/bin/docker inspect --format="Reusing {{.ID}}" "rjw1-data" || exec docker run --name "rjw1-data" --volumes-from "rjw1-data" --entrypoint /bin/true "clusterhq/environment-server:1" (code=exited, status=0/SUCCESS)
 Main PID: 3829 (docker)
   CGroup: /container.slice/container-small.slice/ctr-rjw1.service
           └─3829 /usr/bin/docker run --rm --name rjw1 --volumes-from rjw1-data --env-file /var/lib/containers/env/contents/N4/N4bFpLmjQwT4iZqCa5mIwA -a stdout -a stderr clusterhq/environment-server:1

Aug 14 02:36:25 localhost.localdomain gear[3830]: user: unknown user ctr-rjw1
Aug 14 02:36:25 localhost.localdomain systemd[1]: Started Container rjw1.
Aug 14 02:36:25 localhost.localdomain docker[3829]: export HOME='/'
Aug 14 02:36:25 localhost.localdomain docker[3829]: export HOSTNAME='61f7cbe4d8f4'
Aug 14 02:36:25 localhost.localdomain docker[3829]: export PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
Aug 14 02:36:25 localhost.localdomain docker[3829]: export PWD='/'
Aug 14 02:36:25 localhost.localdomain docker[3829]: export SHLVL='1'
Aug 14 02:36:25 localhost.localdomain docker[3829]: export deep='purple'
Aug 14 02:36:25 localhost.localdomain docker[3829]: export firstname='richard'
Aug 14 02:36:25 localhost.localdomain docker[3829]: export foo='bar'

See openshift/geard#208 for the gear feature discussion.

Next I'll see if it's possible to supply environment variables via the REST API.

[wallrj]

Ok, after some trial and error, I figured out that this is how to set the environment from the REST API

curl -X PUT "http://localhost:43273/container/rjw3" -H "Content-Type: application/json" -d '{"Image": "clusterhq/environment-server:1", "Started":true, "Environment":{"Id":"rjw3", "Variables":[{"Name": "Foo", "Value": "Bar"}]}}'

[wallrj]

I created a geard ticket suggesting they document this. See openshift/geard#256

[itamarst]

Remaining work to be covered by this issue: user facing documentation and entry in What's New. Unless there's something I'm missing? I guess there's also "notice if environment variables changed" which maybe is a follow up issue?