dgoss is a convenience wrapper around goss that aims to bring the simplicity of goss to docker containers.

• video tutorial - Introduction to dgoss tutorial
• blog tutorial - Same as above, but in written format
• dgoss-examples - Repo containing examples of using dgoss to validate docker images

Follow the goss installation instructions

Since goss runs on the target container, dgoss can be used on a Mac OSX system by doing the following:

# Install dgoss
curl -L https://raw.githubusercontent.com/aelsabbahy/goss/master/extras/dgoss/dgoss -o /usr/local/bin/dgoss
chmod +rx /usr/local/bin/dgoss

# Download goss to your preferred location
curl -L https://github.com/aelsabbahy/goss/releases/download/v0.3.6/goss-linux-amd64 -o ~/Downloads/goss-linux-amd64

# Set your GOSS_PATH to the above location
export GOSS_PATH=~/Downloads/goss-linux-amd64

# Use dgoss
dgoss edit ...
dgoss run ...

dgoss [run|edit] <docker_run_params>

Run is used to validate a docker container. It expects a ./goss.yaml file to exist in the directory it was invoked from. In most cases one can just substitute the docker command for the dgoss command, for example:

run:

docker run -e JENKINS_OPTS="--httpPort=8080 --httpsPort=-1" -e JAVA_OPTS="-Xmx1048m" jenkins:alpine

test:

dgoss run -e JENKINS_OPTS="--httpPort=8080 --httpsPort=-1" -e JAVA_OPTS="-Xmx1048m" jenkins:alpine

dgoss run will do the following:

• Run the container with the flags you specified.
• Stream the containers log output into the container as /goss/docker_output.log
  • This allows writing tests or waits against the docker output
• (optional) Run goss with $GOSS_WAIT_OPTS if ./goss_wait.yaml file exists in the current dir
• Run goss with $GOSS_OPTS using ./goss.yaml

Edit will launch a docker container, install goss, and drop the user into an interactive shell. Once the user quits the interactive shell, any goss.yaml or goss_wait.yaml are copied out into the current directory. This allows the user to leverage the goss add|autoadd commands to write tests as they would on a regular machine.

Example:

dgoss edit -e JENKINS_OPTS="--httpPort=8080 --httpsPort=-1" -e JAVA_OPTS="-Xmx1048m" jenkins:alpine

The following environment variables can be set to change the behavior of dgoss.

Location of the goss binary to use. (Default: $(which goss))

Options to use for the goss test run. (Default: --color --format documentation)

Options to use for the goss wait run, when ./goss_wait.yaml exists. (Default: -r 30s -s 1s > /dev/null)

Time to sleep after running container (and optionally goss_wait.yaml) and before running tests. (Default: 0.2)

Location of the goss yaml files. (Default: .)

The name of the variables file relative to GOSS_FILES_PATH to copy into the docker container and use for valiation (i.e. dgoss run) and copy out of the docker container when writing tests (i.e. dgoss edit). If set, the --vars flag is passed to goss validate commands inside the container. If unset (or empty), the --vars flag is omitted, which is the normal behavior. (Default: '').

Strategy used for copying goss files into the docker container. If set to 'mount' a volume with goss files is mounted and log output is streamed into the container as /goss/docker_output.log file. Other strategy is 'cp' which uses 'docker cp' command to copy goss files into docker container. With the 'cp' strategy you lose the ability to write tests or waits against the docker output. The 'cp' strategy is required especially when docker daemon is not on the local machine. (Default 'mount')