Requirements for Containerization (Docker)

This page summarizes Requirements for providing Docker Containers for FIWARE Generic Enablers. Click here for an introduction to Docker.

General Requirements

At least one Dockerfile (hereby named as 'reference Dockerfile'), intended to FIWARE Generic Enabler users, MUST be provided.

The base image (Ubuntu, CentOS, etc.) for such a Dockerfile might depend on each FIWARE Generic Enabler, although some recommendations (see below) are provided. The Dockerfile can be at the root folder of the FIWARE Generic Enabler's Repository or under a folder named docker. Additional Hacker-orientated Dockerfiles MAY be provided as well.

Each Docker image SHOULD define the following tags (present at DockerHub):

  • latest: On the FIWARE Generic Enabler owner's account will correspond to the latest build (latest code snapshot) of the FIWARE Generic Enabler. It might not be stable.

  • <release n>: one tag per relevant and active stable release. The name of the tag will correspond to the name assigned to the release in GitHub.

  • FIWARE_<release n>: one stable release for all FIWARE components. This indicates FIWARE Generic Enablers which will work together.

The reference Dockerfile SHOULD be present under a separate docker folder of the GE repository.

Should your FIWARE Generic Enabler depend on other components (Databases, etc.) you MUST provide a docker-compose.yml file that will allow to instantiate the GE together with its dependencies.

The GitHub repository README.md MUST have a Docker reference - this is a link on the mandatory Docker Pulls README.md badge.

The Read the Docs Installation Documentation MUST include references to the Docker Hub image, and how to configure it

Building Docker Images

There MUST be a Docker Hub specific README for the docker image documentation. This lies in the same directory as the Dockerfile and SHOULD not be a copy of the root GitHub README.md since the required information is not the same.

The Docker README.md MUST list or link to the documentation holding all available ENV variables that can be supplied to the Docker Image and a reasonable definition of each of them.

The Docker README.md MUST give complete instructions about how to work with the corresponding Docker container. Please bear in mind that a copy of this README.md should also be included documentation directly on Dockerhub .

Where configuration occurs via a config file, and the image cannot be driven by ENV variables, a sample config file SHOULD be supplied and injected as part of the Docker build. Reference Dockerfiles SHOULD NOT COPY . default configuration directly from GitHub.

The reference Dockerfile SHOULD be split into Multiple Stages:

This is good practice to reduce the size of the layers. Although the names of the stages are not that important it is easier to align with a common naming convention. The following common names for build stages are recommended and MAY be used:

  • init - Gather Sources
  • builder - Build Sources
  • distroless - “Distroless” Build (where supported)
  • node-slim etc. - where a build stage aligns to a Docker official Image use that as the name of the stage.

Note that the main supported distro build must be the last one in the file as it will be the default.

Flexible base images SHOULD be supported using build-args, an example can be seen below:

docker build -t rhel-build  \
  --build-arg DISTRO=registry.access.redhat.com/ubi7/nodejs-12 \
  --build-arg NODE_VERSION=12 \
  --build-arg BUILDER=registry.access.redhat.com/ubi7/ubi \
  --build-arg PACKAGE_MANAGER=yum \
  --no-cache \
  .

The following names for build arguments are recommended and MAY be used:

  • BUILDER - baseline Docker image for creating sources
  • DISTRO - baseline Docker image for default build
  • DISTROLESS - baseline Docker image for “distroless” build
  • PACKAGE_MANAGER - name of package manager to use yum, apt, apk etc.
  • <NODE>_VERSION - Supported Version ( plus equivalents for Python, Java etc.)
  • GITHUB_ACCOUNT - GE Owner account on GitHub
  • GITHUB_REPOSITORY - Name of the source code repository on GitHub
  • DOWNLOAD - e.g. by GitHash or tag version
  • SOURCE_BRANCH - e.g. master

Where flexible base images are available, the README MUST state how to build them and which build options are officially supported by the GE Owner.

Running Docker Images

If the reference Dockerfile hides sensitive information (e.g. passwords) using Docker Secrets, the README.md MUST list all available ENV variables which have an equivalent _FILE that can be supplied by secrets.

It MUST be possible to supply sensitive information using the Docker Secrets mechanism as well as plain text variables for testing. Sensitive information (e.g. passwords) MUST NOT be passed in plain text - ENV variables alone.

It SHOULD be possible to configure the FIWARE Generic Enabler config entirely through - ENV variables. Where this is not possible, the README.md SHOULD explain how to mount a volume to set the configuration.

Publication Requirements

The FIWARE Generic Enabler owner will be responsible for Docker publication and maintenance operations. Docker builds SHOULD be automated. FIWARE Generic Enabler Owner's build should be triggered by git push, FIWARE's one will be triggered by new tagged releases.

Docker containers MUST be tested before being published to the community. Error in Docker materials of a FIWARE Generic Enabler will be considered as critical and MUST be fixed immediately.

Maintenance and release of interim point releases MUST be done using the FIWARE Generic Enabler Owner own contributor account.

A webhook MUST be added so that the FIWARE Infrastructure is informed whenever a release version is tagged.

Builds of components which do not successfully integrate with r/fiware/orion/latest will not be added to the FIWARE account. When changes have been made, a SemVer release on the source code will be required in order to complete the release. This will kick off the FIWARE build. Obviously, it is essential that such a build passes the mandatory integration tests.

Dockerfiles SHOULD follow best practices as described here

Dockerfiles SHOULD be based on the latest LTS (Long Term Support) release of the base image - e.g. ubuntu:20.04, node:14, etc.

Although default values SHOULD be defined, exposed ports MUST NOT be fixed, and MUST be configurable using ENV variables.

Dockerfiles should be publicly available, and therefore can be read by outside developers and can reflect on the quality of the product in question. Although image size is not everything, there are several ways to reduce the bloat of docker images and good practice should be followed:

  • Where possible, base the image on debian:9-slim rather than Ubuntu.

  • Node-based images should use node-carbon-slim where possible (which is also debian-based).

  • Builds should not package development dependencies and should remove unnecessary tools such as wget, curl, and so on - if necessary load these tools and remove them within the same layer.

  • Use the RUN git clone method of obtaining source code instead of ADD/COPY in case source code can be deleted.

  • Consider adding build-args to be able to download latest/stable/specific release of the codebase.

  • Additional alpine-based builds may be requested for some components.

Label description content

Dockerfiles SHOULD put the following static common Open Container Initiative labels inside the Dockerfile:

Name Description Example
org.opencontainers.image.authors Email addresses of responsible contacts iot_support@tid.es
org.opencontainers.image.description Description of the component An Internet of Things Agent for the Ultralight 2.0 protocol (with AMQP, HTTP and MQTT transports). This IoT Agent is designed to be a bridge betweenUltralight and the NGSI interface of a context broker.
org.opencontainers.image.documentation Link to the documentation https://fiware-iotagent-ul.rtfd.io/
org.opencontainers.image.licenses The license type AGPL-3.0-only
org.opencontainers.image.revision The GitHash or branch the image was built from d0698fad9a0880edcbdf2cc23ba775d81c3f51c1
org.opencontainers.image.source Location where the source code can be found. https://github.com/telefonicaid/iotagent-ul
org.opencontainers.image.title The title of the image IoT Agent for the Ultralight 2.0 protocol
org.opencontainers.image.vendor The name of the caretaker organization. Telefónica Investigación y Desarrollo, S.A.U

An example of Static Labels can be found in this Dockerfile

Dockerfiles SHOULD also add the following dynamic labels inside the Dockerfile:

Name Description Example
org.opencontainers.image.created The date the image was built. 2020-10-20
org.opencontainers.image.version The SemVer release of the component 1.15.0

An example of Dynamic Labelling can be found in this Build Hook

For the automation of security alerts, Dockerfiles SHOULD put the following additional FIWARE related labels inside the Dockerfile:

Name Description Example
org.fiware.contact.localpart A comma separated partial email addresses of responsible contacts fernando.lopez,jason.fox
org.fiware.contact.domain An email server domain name of responsible contacts fiware.org

Note that the Dockerfile MAINTAINER instruction is deprecated. The LABEL maintainer instruction is a much more flexible version of this and you should use it instead, as it enables setting any metadata you require, and can be viewed easily, for example with docker inspect. See section Label description content for more details.

Note that Image labels can be read using the docker inspect command:

docker inspect --format '{{json .Config.Labels}}' test | jq .

Examples

Support

Should you have any question please send an email to fiware-help@lists.fiware.org