--- description: components and formatting examples used in Docker's docs title: Code blocks toc_max: 3 --- Rouge provides lots of different code block "hints". If you leave off the hint, it tries to guess and sometimes gets it wrong. These are just a few hints that we use often. ## Variables If your example contains a placeholder value that's subject to change, use the format `<[A-Z_]+>` for the placeholder value: `` ```none export name= ``` This syntax is reserved for variable names, and will cause the variable to be rendered in a special color and font style. ## Highlight lines ```text {hl_lines=[7,8]} incoming := map[string]interface{}{ "asdf": 1, "qwer": []interface{}{}, "zxcv": []interface{}{ map[string]interface{}{}, true, int(1e9), "tyui", }, } ``` ````markdown ```go {hl_lines=[7,8]} incoming := map[string]interface{}{ "asdf": 1, "qwer": []interface{}{}, "zxcv": []interface{}{ map[string]interface{}{}, true, int(1e9), "tyui", }, } ``` ```` ## Collapsible code blocks ```dockerfile {collapse=true} # syntax=docker/dockerfile:1 ARG GO_VERSION="1.21" FROM golang:${GO_VERSION}-alpine AS base ENV CGO_ENABLED=0 ENV GOPRIVATE="github.com/foo/*" RUN apk add --no-cache file git rsync openssh-client RUN mkdir -p -m 0700 ~/.ssh && ssh-keyscan github.com >> ~/.ssh/known_hosts WORKDIR /src FROM base AS vendor # this step configure git and checks the ssh key is loaded RUN --mount=type=ssh < Welcome to nginx! ``` ## Markdown ```markdown # Hello ``` If you want to include a triple-fenced code block inside your code block, you can wrap your block in a quadruple-fenced code block: `````markdown ````markdown # Hello ```go log.Println("did something") ``` ```` ````` ## ini ```ini [supervisord] nodaemon=true [program:sshd] command=/usr/sbin/sshd -D ``` ## Dockerfile ```dockerfile # syntax=docker/dockerfile:1 FROM ubuntu RUN apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8 RUN echo "deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main" > /etc/apt/sources.list.d/pgdg.list RUN apt-get update && apt-get install -y python-software-properties software-properties-common postgresql-9.3 postgresql-client-9.3 postgresql-contrib-9.3 # Note: The official Debian and Ubuntu images automatically ``apt-get clean`` # after each ``apt-get`` USER postgres RUN /etc/init.d/postgresql start &&\ psql --command "CREATE USER docker WITH SUPERUSER PASSWORD 'docker';" &&\ createdb -O docker docker RUN echo "host all all 0.0.0.0/0 md5" >> /etc/postgresql/9.3/main/pg_hba.conf RUN echo "listen_addresses='*'" >> /etc/postgresql/9.3/main/postgresql.conf EXPOSE 5432 VOLUME ["/etc/postgresql", "/var/log/postgresql", "/var/lib/postgresql"] CMD ["/usr/lib/postgresql/9.3/bin/postgres", "-D", "/var/lib/postgresql/9.3/main", "-c", "config_file=/etc/postgresql/9.3/main/postgresql.conf"] ``` ## YAML ```yaml authorizedkeys: image: dockercloud/authorizedkeys deployment_strategy: every_node autodestroy: always environment: - AUTHORIZED_KEYS=ssh-rsa AAAAB3Nsomelongsshkeystringhereu9UzQbVKy9o00NqXa5jkmZ9Yd0BJBjFmb3WwUR8sJWZVTPFL volumes: /root:/user:rw ```