init

Dockerfile

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+FROM ubuntu:24.04 AS ubuntu
+
+# setting non-interactive mode for apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# update system and install the required stuff
+RUN apt-get update && apt-get upgrade -y
+RUN apt-get install -y --no-install-recommends \
+gosu
+
+# install packages appearing in packages.list
+# clean up chache and remove package lists
+COPY ./packages.list /tmp
+RUN xargs apt-get install -y --no-install-recommends </tmp/packages.list && \
+apt-get clean && \
+rm /tmp/packages.list
+
+
+# install what can not be installed with
+# package manager 
+COPY ./build_time_scripts.sh /tmp
+COPY ./custom /tmp/custom
+RUN /tmp/build_time_scripts.sh /tmp/custom && \
+rm -rf /tmp/build_time_scripts.sh /tmp/custom
+
+
+# set working dir inside the container
+WORKDIR /home/ubuntu
+
+# password to log in as ubuntu user
+ENV SECRET="ubuntu"
+
+# copy enrypoint script
+COPY ./entrypoint.sh /usr/bin/entrypoint-docker.sh
+
+ENTRYPOINT ["/bin/sh", "/usr/bin/entrypoint-docker.sh"]
+CMD ["/usr/bin/bash"]

Makefile

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+#image basename
+BASENAME=devenv
+# TODO use git tag
+IMAGE_NAME=$(BASENAME):latest
+
+build:
+	$(info BUILDING IMAGE NAME: $(IMAGE_NAME))
+	docker build \
+		-t $(IMAGE_NAME) \
+		-f Dockerfile .
+	docker image ls $(IMAGE_NAME)
+
+

README.md

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+# devenv
+**devenv** is a tool to quickly build a Docker image based on Ubuntu 22.04 with
+easily customisable set of packages. The image is built with an entrypoint script
+which lets you set up an unprivileged user in container OS. 
+
+The whole story is intended for developers needing to experiment with different
+versions of build tools etc.
+
+## Customise
+1. Customize packages that you want to install into the
+container OS. Just edit the **packages.list** putting
+one package name per line.
+
+2. Add shell scripts or binaries to **./custom** directory. These 
+will run at build time as **root** and the produced result will be 
+baked into the image.
+
+3. **(optional)** edit Makefile, Dockerfile, entrypoint.sh accoriding
+to your requirements.
+
+## Build the image
+This builds Docker image with Ubuntu 22.04 as base
+installing the tools you chose above. Note that build 
+executes all scripts in **./scripts** directory if any are present.
+```bash
+make build
+```
+## Entrypoint
+Entrypoint script creates an unprivileged user in container system.
+Username, gid and uig can be altered when launching the container by passing environment
+variables to docker run.
+
+If no environment variables were passed to docker run, the unprivileged user will
+default to **developer:developer** with uig/gid **1001:1001**.
+
+By default the unprivileged user created by entrpoint script has passwordless sudo.
+If this is not the desired behaviour - consider editing **entrypoint.sh** before
+building the image.
+
+## Create launch script
+This will create a bash script that runs the Docker container from the image 
+built above with your current username, uid and gid. Since username, uid and 
+gid are the same as in your host system you can safely mount anything from 
+your host system into container without creating mess in host OS.
+
+By default the launch script mounts your home directory into the unprivileged 
+user's home in the container. Edit the produced script as  approprite if this 
+is not the desired behaviour.
+```bash
+make script
+```
+
+## Create and install launch script
+This will create the launch script (see above) and place it into you
+**$HOME/.local/bin** creating the directory is if does not exist.
+```bash
+make install 
+```

build_time_scripts.sh

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+# exit on errors
+set -e
+# now let's fire up all the scripts from the
+# directory which we received as a second argument
+if [ "$(ls $1)" ]; then 
+	for script in $1/*
+	do
+		echo "executing $script"
+		$script
+	done
+else
+	echo "custom scripts directory is empty"
+fi

custom/010_vanilla_go.sh

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+# install vanilla Go 1.24.3
+set -e
+echo "fetching go compiler"
+curl --location https://go.dev/dl/go1.24.3.linux-amd64.tar.gz -o /tmp/go.tar.gz
+echo "unpacking go compiler..."
+tar -xzf /tmp/go.tar.gz -C /usr/local
+echo "removing archive"
+rm /tmp/go.tar.gz
+ln -s /usr/local/go/bin/* /usr/bin
+echo "Go 1.24.3 installed into /usr/local"

entrypoint.sh

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+set -e
+
+# set password
+echo "ubuntu:${SECRET}" | chpasswd
+
+mkdir /run/sshd 
+/sbin/sshd -o "PasswordAuthentication=yes"
+
+# add ubuntu to groups
+usermod -aG sudo ubuntu
+
+exec gosu ubuntu:ubuntu $@

packages.list

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+sudo
+openssh-server
+openssh-client
+curl
+wget
+ca-certificates
+tzdata
+git
+make
+build-essential
+tree
+htop
+iproute2
+openssh-client