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Configuring an Application

A Deis application stores config in environment variables.

Configure the Application

Use deis config to modify environment variables for a deployed application.

$ deis help config
Valid commands for config:

config:list        list environment variables for an app
config:set         set environment variables for an app
config:unset       unset environment variables for an app
config:pull        extract environment variables to .env
config:push        set environment variables from .env

Use `deis help [command]` to learn more.

When config is changed, a new release is created and deployed automatically.

You can set multiple environment variables with one deis config:set command, or with deis config:push and a local .env file.

$ deis config:set FOO=1 BAR=baz && deis config:pull
$ cat .env
FOO=1
BAR=baz
$ echo "TIDE=high" >> .env
$ deis config:push
Creating config... done, v4

=== yuppie-earthman
DEIS_APP: yuppie-earthman
FOO: 1
BAR: baz
TIDE: high

Attach to Backing Services

Deis treats backing services like databases, caches and queues as attached resources. Attachments are performed using environment variables.

For example, use deis config to set a DATABASE_URL that attaches the application to an external PostgreSQL database.

$ deis config:set DATABASE_URL=postgres://user:pass@example.com:5432/db
=== peachy-waxworks
DATABASE_URL: postgres://user:pass@example.com:5432/db

Detachments can be performed with deis config:unset.

Custom Domains

You can use deis domains to add or remove custom domains to your application:

$ deis domains:add hello.bacongobbler.com
Adding hello.bacongobbler.com to finest-woodshed... done

Once that's done, you can go into your DNS registrar and set up a CNAME from the new appname to the old one:

$ dig hello.deisapp.com
[...]
;; ANSWER SECTION:
hello.bacongobbler.com.         1759    IN    CNAME    finest-woodshed.deisapp.com.
finest-woodshed.deisapp.com.    270     IN    A        172.17.8.100

!!! note Setting a CNAME for your root domain can cause issues. Setting your @ record to be a CNAME causes all traffic to go to the other domain, including mail and the SOA ("start-of-authority") records. It is highly recommended that you bind a subdomain to an application, however you can work around this by pointing the @ record to the address of the load balancer (if any).

Custom Health Checks

By default, Workflow only checks that your application containers start in their Pod. If you would like Kubernetes to respond to appliation health, you may add a health check by configuring URL, port, initial delay, and timeout values. The health checks are implemented as Kubernetes container probes.

  • HEALTHCHECK_URL: the URL to visit for the health check (String, Default: /)
  • HEALTHCHECK_PORT: the TCP port to use for the health check (Integer, Default: 80 or 5000)
  • HEALTHCHECK_INITIAL_DELAY: number of seconds to wait before sending health checks (Integer, Default: 50)
  • HEALTHCHECK_TIMEOUT: number of seconds to wait before assuming the application is unhealthy (Integer, Default: 50)

Configure these health checks on a per-application basis using deis config:set:

$ deis config:set HEALTHCHECK_URL=/200.html
=== peachy-waxworks
HEALTHCHECK_URL: /200.html
$ deis config:set HEALTHCHECK_INITIAL_DELAY=5
=== peachy-waxworks
HEALTHCHECK_INITIAL_DELAY: 5
HEALTHCHECK_URL: /200.html
$ deis config:set HEALTHCHECK_TIMEOUT=5
=== peachy-waxworks
HEALTHCHECK_TIMEOUT: 5
HEALTHCHECK_INITIAL_DELAY: 5
HEALTHCHECK_URL: /200.html
$ deis config:set HEALTHCHECK_PORT=5000
=== peachy-waxworks
HEALTHCHECK_TIMEOUT: 5
HEALTHCHECK_INITIAL_DELAY: 5
HEALTHCHECK_URL: /200.html
HEALTHCHECK_PORT: 5000

Only HTTP-based health checks using the GET method are supported at this time.

If an application times out, or responds to a health check with a response code outside the 200-399 range, Kubernetes will stop sending requests to the application and re-schedule the pod to another node.

Configured health checks also modify the default application deploy behavior. When starting a new pod, Workflow will wait for the health check to pass before moving onto the next pod.

Track Changes

Each time a build or config change is made to your application, a new release is created. Track changes to your application using deis releases.

$ deis releases
=== peachy-waxworks Releases
v4      3 minutes ago                     gabrtv deployed d3ccc05
v3      1 hour 17 minutes ago             gabrtv added DATABASE_URL
v2      6 hours 2 minutes ago             gabrtv deployed 7cb3321
v1      6 hours 2 minutes ago             gabrtv deployed deis/helloworld

Rollback the Application

Use deis rollback to revert to a previous release.

$ deis rollback v2
Rolled back to v2

$ deis releases
=== folksy-offshoot Releases
v5      Just now                          gabrtv rolled back to v2
v4      4 minutes ago                     gabrtv deployed d3ccc05
v3      1 hour 18 minutes ago             gabrtv added DATABASE_URL
v2      6 hours 2 minutes ago             gabrtv deployed 7cb3321
v1      6 hours 3 minutes ago             gabrtv deployed deis/helloworld

!!! note All releases (including rollbacks) append to the release ledger.