Using Dockerfiles

Drycc Container Registry allows you to deploy your Docker-based app to Drycc. Both Common Runtime and Private Spaces are supported.

Drycc supports deploying applications via Dockerfiles. A Dockerfile automates the steps for crafting a [Container Image][]. Dockerfiles are incredibly powerful but require some extra work to define your exact application runtime environment.

Add SSH Key

For Dockerfile based application deploys via git push, Drycc Workflow identifies users via SSH keys. SSH keys are pushed to the platform and must be unique to each user.

  • See this document for instructions on how to generate an SSH key.

  • Run drycc keys:add to upload your SSH key to Drycc Workflow.

$ drycc keys:add ~/.ssh/
Uploading to drycc... done

Read more about adding/removing SSH Keys here.

Prepare an Application

If you do not have an existing application, you can clone an example application that demonstrates the Dockerfile workflow.

$ git clone
$ cd helloworld

Dockerfile Requirements

In order to deploy Dockerfile applications, 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 Container 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.

$ drycc create
Creating application... done, created folksy-offshoot
Git remote drycc added

Push to Deploy

Use git push drycc master to deploy your application.

$ git push drycc master
Counting objects: 13, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (13/13), done.
Writing objects: 100% (13/13), 1.99 KiB | 0 bytes/s, done.
Total 13 (delta 2), reused 0 (delta 0)
-----> Building Docker image
Uploading context 4.096 kB
Uploading context
Step 0 : FROM drycc/base:latest
 ---> 60024338bc63
Step 1 : RUN wget -O /tmp/go1.2.1.linux-amd64.tar.gz -q
 ---> Using cache
 ---> cf9ef8c5caa7
Step 2 : RUN tar -C /usr/local -xzf /tmp/go1.2.1.linux-amd64.tar.gz
 ---> Using cache
 ---> 515b1faf3bd8
Step 3 : RUN mkdir -p /go
 ---> Using cache
 ---> ebf4927a00e9
Step 4 : ENV GOPATH /go
 ---> Using cache
 ---> c6a276eded37
Step 5 : ENV PATH /usr/local/go/bin:/go/bin:$PATH
 ---> Using cache
 ---> 2ba6f6c9f108
Step 6 : ADD . /go/src/
 ---> 94ab7f4b977b
Removing intermediate container 171b7d9fdb34
Step 7 : RUN cd /go/src/ && go install -v .
 ---> Running in 0c8fbb2d2812
 ---> 13b5af931393
Removing intermediate container 0c8fbb2d2812
Step 8 : ENV PORT 80
 ---> Running in 9b07da36a272
 ---> 2dce83167874
Removing intermediate container 9b07da36a272
Step 9 : CMD ["/go/bin/helloworld"]
 ---> Running in f7b215199940
 ---> b1e55ce5195a
Removing intermediate container f7b215199940
Step 10 : EXPOSE 80
 ---> Running in 7eb8ec45dcb0
 ---> ea1a8cc93ca3
Removing intermediate container 7eb8ec45dcb0
Successfully built ea1a8cc93ca3
-----> Pushing image to private registry

       Launching... done, v2

-----> folksy-offshoot deployed to Drycc

       To learn more, use `drycc help` or visit

To ssh://[email protected]:2222/folksy-offshoot.git
 * [new branch]      master -> master

$ curl -s
Welcome to Drycc!
See the documentation at for more information.

Because a Dockerfile application is detected, 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.

Container Build Arguments

As of Workflow v2.13.0, users can inject their application config into the Container image using Container build arguments. To opt into this, users must add a new environment variable to their application:


Every environment variable set with drycc config:set will then be available for use inside the user’s Dockerfile. For example, if a user runs drycc config:set POWERED_BY=Workflow, the user can utilize that build argument in their Dockerfile:

RUN echo "Powered by $POWERED_BY" > /etc/motd