docker.md

+++ title = "Docker container" weight = 4 +++

Docker container

If you don't want to install or run gw on your server, you can also use the prebuilt Docker images at danielgrant/gw.

Variants

The gw Docker images come in two flavours: the default image is based on Debian, while the Alpine tag is a smaller, more secure variant. For most use-cases the Debian-based is a safer option, but if you know what you are doing, the Alpine image can be useful.

# Pull Debian-based
docker pull danielgrant/gw
docker pull danielgrant/gw:0.2.2

# Pull Alpine-based
docker pull danielgrant/gw:alpine
docker pull danielgrant/gw:0.2.2-alpine

Usage

If you just want to pull a repository or run simple scripts, you can run the container with docker. You can mount a repository to a directory and watch it. For example:

docker run -d --name gw -v /path/to/repo:/app danielgrant/gw /app

You can also run scripts, but these images are very small and only have a few programs set up:

docker run -d --name gw -v /path/to/repo:/app danielgrant/gw /app -s "cp -r build/ html/"

If you prefer to use docker-compose, you can copy this file to a docker-compose.yaml and run docker compose up -d:

# docker-compose.yaml
version: "3"

services:
  gw:
    container_name: gw
    image: danielgrant/gw
    command: /app
    volumes:
      - type: volume
        source: /path/to/repo
        target: /app

Customization

Build on top of gw

The default image is useful for some cases, but most of the time we need more some other programs for our scripts. In this case it can work to build an image on top of the gw docker image. Copy this into a Dockerfile and specify gw as a base image:

# Dockerfile
# It is recommended to specify the version
FROM danielgrant/gw:0.2.2

# Install dependencies
RUN apt-get update && \
    apt-get install -y python3

# Don't add `gw` here
CMD ["/app", "-s", "python update.py"]

You can build this image into gw-python and run it similarly as before:

docker build -t gw-python .
docker run -d --name gw-python -v /path/to/repo:/app gw-python

If you prefer, you can also build this as part of a docker-compose, with running docker compose up -d --build:

# docker-compose.yaml
version: "3"

services:
  gw:
    container_name: gw-python
    build: .
    command: /app
    volumes:
      - type: volume
        source: /path/to/repo
        target: /app

Copy binary from gw

It is useful to install the dependencies on top of gw, but most applications have many dependencies and complicated setups, and are already running on Docker. In these cases it is often preferable to build the gw image on top of the already existing application image.

NOTE: This doesn't mean that these should be running in the same container, but they can use the same base image in two separate containers. It is a common wisdom that one container should run one thing.

For this we can start off of our application image as a base layer and add the gw binary in a COPY layer. Also note that gw needs ca-certificates, openssl and openssh-client installed, so it can interact with the remote server. If your base image doesn't have these, you should install them as well:

FROM example.org/registry/node-image:ubuntu

# Install `gw` dependencies
RUN apt-get update && \
    apt-get install -y ca-certificates openssl openssh-client

# Copy from the `gw` image
COPY --from danielgrant/gw:0.2.2 /usr/bin/gw /usr/bin/gw

ENTRYPOINT ["/usr/bin/gw"]
CMD ["/app", "-s", "npm run build"]

It is similar with alpine, but only the ca-certificates and openssh-client is required:

FROM example.org/registry/node-image:alpine

# Install `gw` dependencies
RUN apk add ca-certificates openssh-client

# Copy from the `gw` image
COPY --from danielgrant/gw:0.2.2-alpine /usr/bin/gw /usr/bin/gw

ENTRYPOINT ["/usr/bin/gw"]
CMD ["/app", "-s", "npm run build"]

You can build and use it similarly to the previous step.