Using Docker Images
3 minute read
Drycc supports deploying applications via an existing Docker Image. This is useful for integrating Drycc into Docker-based CI/CD pipelines.
Prepare an Application
Start by cloning an example application:
$ git clone https://github.com/drycc/example-dockerfile-http.git
$ cd example-dockerfile-http
Next use your local docker
client to build the image and push
it to DockerHub.
$ docker build -t <username>/example-dockerfile-http .
$ docker push <username>/example-dockerfile-http
Docker Image Requirements
In order to deploy Docker images, they must conform to the following requirements:
- The Dockerfile must use the
EXPOSE
directive to expose exactly one port. - That port must be listening for an HTTP connection.
- The Dockerfile must use the
CMD
directive to define the default process that will run within the container. - The Docker image must contain bash to run processes.
!!! note
Note that if you are using a private registry of any kind (gcr
or other) the application environment must include a $PORT
config variable that matches the EXPOSE
’d port, example: drycc config:set PORT=5000
. See Configuring Registry for more info.
Create an Application
Use drycc create
to create an application on the controller.
$ mkdir -p /tmp/example-dockerfile-http && cd /tmp/example-dockerfile-http
$ drycc create example-dockerfile-http --no-remote
Creating application... done, created example-dockerfile-http
!!! note
For all commands except for drycc create
, the drycc
client uses the name of the current directory
as the app name if you don’t specify it explicitly with --app
.
Deploy the Application
Use drycc pull
to deploy your application from DockerHub or
a public registry.
$ drycc pull <username>/example-dockerfile-http:latest
Creating build... done, v2
$ curl -s http://example-dockerfile-http.local3.dryccapp.com
Powered by Drycc
Because you are deploying a Docker image, the web
process type is automatically scaled to 1 on first deploy.
Use drycc scale web=3
to increase web
processes to 3, for example. Scaling a
process type directly changes the number of Containers
running that process.
Private Registry
To deploy Docker images from a private registry or from a private repository, use drycc registry
to attach credentials to your application. These credentials are the same as you’d use when running
docker login
at your private registry.
To deploy private Docker images, take the following steps:
- Gather the username and password for the registry, such as a Quay.io Robot Account or a GCR.io Long Lived Token
- Run
drycc registry:set username=<the-user> password=<secret> -a <application-name>
- Now perform
drycc pull
as normal, against an image in the private registry
When using a GCR.io Long Lived Token, the JSON blob will have to be compacted first using a
tool like jq and then used in the password field in drycc registry:set
. For the username, use
_json_key
. For example:
drycc registry:set username=_json_key password="$(cat google_cloud_cred.json | jq -c .)"
When using a private registry the docker images are no longer pulled into the Drycc Internal Registry via
the Drycc Workflow Controller but rather is managed by Kubernetes. This will increase security and overall speed,
however the application port
information can no longer be discovered. Instead the application port
information can be set via
drycc config:set PORT=80
prior to setting the registry information.
!!! note Currently GCR.io and ECR in short lived auth token mode are not supported.
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