The Kubernetes platform.
The Package manager.
The Open Service Broker.
A Drycc application stores config in environment variables.
drycc config to modify environment variables for a deployed application.
$ drycc 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 `drycc 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
drycc config:set command,
drycc config:push and a local .env file.
$ drycc config:set FOO=1 BAR=baz && drycc config:pull $ cat .env FOO=1 BAR=baz $ echo "TIDE=high" >> .env $ drycc config:push Creating config... done, v4 === yuppie-earthman DRYCC_APP: yuppie-earthman FOO: 1 BAR: baz TIDE: high
Drycc treats backing services like databases, caches and queues as attached resources. Attachments are performed using environment variables.
For example, use
drycc config to set a
DATABASE_URL that attaches
the application to an external PostgreSQL database.
$ drycc config:set DATABASE_URL=postgres://user:firstname.lastname@example.org:5432/db === peachy-waxworks DATABASE_URL: postgres://user:email@example.com:5432/db
Detachments can be performed with
By default, apps using the [Imagebuilder] will reuse the latest image data. When deploying applications that depend on third-party libraries that have to be fetched, this could speed up deployments a lot. In order to make use of this, the buildpack must implement the cache by writing to the cache directory. Most buildpacks already implement this, but when using custom buildpacks, it might need to be changed to make full use of the cache.
In some cases, cache might not speed up your application. To disable caching, you can set the
DRYCC_DISABLE_CACHE variable with
drycc config:set DRYCC_DISABLE_CACHE=1. When you disable the
cache, Drycc will clear up files it created to store the cache. After having it turned off, run
drycc config:unset DRYCC_DISABLE_CACHE to re-enable the cache.
Use the following procedure to clear the cache:
$ drycc config:set DRYCC_DISABLE_CACHE=1 $ git commit --allow-empty -m "Clearing Drycc cache" $ git push drycc # (if you use a different remote, you should use your remote name) $ drycc config:unset DRYCC_DISABLE_CACHE
By default, Workflow only checks that the application starts in their Container. If it is preferred to have Kubernetes respond to application health, a health check may be added by configuring a health check probe for the application.
The health checks are implemented as Kubernetes container probes. A
readiness probe can be configured, and each probe can be of type
tcpSocket depending on the type of probe the container requires.
A liveness probe is useful for applications running for long periods of time, eventually transitioning to broken states and cannot recover except by restarting them.
Other times, a readiness probe is useful when the container is only temporarily unable to serve, and will recover on its own. In this case, if a container fails its readiness probe, the container will not be shut down, but rather the container will stop receiving incoming requests.
httpGet probes are just as it sounds: it performs a HTTP GET operation on the Container. A
response code inside the 200-399 range is considered a pass.
exec probes run a command inside the Container to determine its health, such as
cat /var/run/myapp.pid or a script that determines when the application is ready. An exit code of
zero is considered a pass, while a non-zero status code is considered a fail.
tcpSocket probes attempt to open a socket in the Container. The Container is only considered
healthy if the check can establish a connection.
tcpSocket probes accept a port number to perform
the socket connection on the Container.
Health checks can be configured on a per-proctype basis for each application using
drycc healthchecks:set. If no type is mentioned then the health checks are applied to default proc types, web or cmd, whichever is present. To
httpGet liveness probe:
$ drycc healthchecks:set liveness httpGet 80 --type cmd === peachy-waxworks Healthchecks cmd: Liveness -------- Initial Delay (seconds): 50 Timeout (seconds): 50 Period (seconds): 10 Success Threshold: 1 Failure Threshold: 3 Exec Probe: N/A HTTP GET Probe: Path="/" Port=80 HTTPHeaders= TCP Socket Probe: N/A Readiness --------- No readiness probe configured.
If the application relies on certain headers being set (such as the
Host header) or a specific
URL path relative to the root, you can also send specific HTTP headers:
$ drycc healthchecks:set liveness httpGet 80 \ --path /welcome/index.html \ --headers "X-Client-Version:v1.0,X-Foo:bar" === peachy-waxworks Healthchecks web/cmd: Liveness -------- Initial Delay (seconds): 50 Timeout (seconds): 50 Period (seconds): 10 Success Threshold: 1 Failure Threshold: 3 Exec Probe: N/A HTTP GET Probe: Path="/welcome/index.html" Port=80 HTTPHeaders=[X-Client-Version=v1.0] TCP Socket Probe: N/A Readiness --------- No readiness probe configured.
To configure an
exec readiness probe:
$ drycc healthchecks:set readiness exec -- /bin/echo -n hello --type cmd === peachy-waxworks Healthchecks cmd: Liveness -------- No liveness probe configured. Readiness --------- Initial Delay (seconds): 50 Timeout (seconds): 50 Period (seconds): 10 Success Threshold: 1 Failure Threshold: 3 Exec Probe: Command=[/bin/echo -n hello] HTTP GET Probe: N/A TCP Socket Probe: N/A
You can overwrite a probe by running
drycc healthchecks:set again:
$ drycc healthchecks:set readiness httpGet 80 --type cmd === peachy-waxworks Healthchecks cmd: Liveness -------- No liveness probe configured. Readiness --------- Initial Delay (seconds): 50 Timeout (seconds): 50 Period (seconds): 10 Success Threshold: 1 Failure Threshold: 3 Exec Probe: N/A HTTP GET Probe: Path="/" Port=80 HTTPHeaders= TCP Socket Probe: N/A
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.
Workflow supports isolating applications onto a set of nodes using
In order to use tags, you must first launch your cluster with the proper node labels. If you do not, tag commands will fail. Learn more by reading "Assigning Pods to Nodes".
Once your nodes are configured with appropriate label selectors, use
drycc tags:set to restrict
the application to those nodes:
$ drycc tags:set environ=prod Applying tags... done, v4 environ prod