Move main package to root and add Docker image (#127)

- Move main package to root.
- Update golanci-lint configuration.
- Build and push Docker container image.
- Refine GitHub Actions workflow.

.devcontainer/Dockerfile

@@ -0,0 +1,35 @@
+FROM golang:1.16
+
+# [Option] Install zsh
+ARG INSTALL_ZSH="true"
+# [Option] Upgrade OS packages to their latest versions
+ARG UPGRADE_PACKAGES="false"
+# [Option] Enable non-root Docker access in container
+ARG ENABLE_NONROOT_DOCKER="true"
+# [Option] Use the OSS Moby Engine instead of the licensed Docker Engine
+ARG USE_MOBY="true"
+
+# Install needed packages and setup non-root user. Use a separate RUN statement to add your
+# own dependencies. A user of "automatic" attempts to reuse an user ID if one already exists.
+ARG USERNAME=automatic
+ARG USER_UID=1000
+ARG USER_GID=$USER_UID
+COPY library-scripts/*.sh /tmp/library-scripts/
+RUN apt-get update \
+    && /bin/bash /tmp/library-scripts/common-debian.sh "${INSTALL_ZSH}" "${USERNAME}" "${USER_UID}" "${USER_GID}" "${UPGRADE_PACKAGES}" \
+    # Use Docker script from script library to set things up
+    && /bin/bash /tmp/library-scripts/docker-in-docker-debian.sh "${ENABLE_NONROOT_DOCKER}" "${USERNAME}" "${USE_MOBY}" \
+    # Clean up
+    && apt-get autoremove -y && apt-get clean -y && rm -rf /var/lib/apt/lists/* /tmp/library-scripts/
+
+VOLUME [ "/var/lib/docker" ]
+
+# Setting the ENTRYPOINT to docker-init.sh will start up the Docker Engine 
+# inside the container "overrideCommand": false is set in devcontainer.json. 
+# The script will also execute CMD if you need to alter startup behaviors.
+ENTRYPOINT [ "/usr/local/share/docker-init.sh" ]
+CMD [ "sleep", "infinity" ]
+
+# [Optional] Uncomment this section to install additional OS packages.
+# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+#     && apt-get -y install --no-install-recommends <your-package-list-here>

.devcontainer/devcontainer.json

@@ -1,26 +1,29 @@
 // For format details, see https://aka.ms/vscode-remote/devcontainer.json or
 // https://github.com/microsoft/vscode-dev-containers
 {
-	"name": "Go",
-	"image": "golang:1.16",
-	"runArgs": [
-		"--cap-add=SYS_PTRACE",
-		"--security-opt",
-		"seccomp=unconfined"
-	],
+	"name": "Go with Docker in Docker",
+	"dockerFile": "Dockerfile",
+	"runArgs": ["--init", "--privileged"],
+	"overrideCommand": false,
+
 	// Set *default* container specific settings.json values on container create.
 	"settings": {
-		"terminal.integrated.shell.linux": "/bin/bash",
+		"terminal.integrated.shell.linux": "/bin/zsh",
 		"go.gopath": "/go"
 	},
+
 	// Add the IDs of extensions you want installed when the container is created.
 	"extensions": [
-		"golang.Go"
+		"golang.Go",
+		"ms-azuretools.vscode-docker"
 	],
+
 	// Use 'forwardPorts' to make a list of ports inside the container available locally.
 	// "forwardPorts": [],
+
 	// Use 'postCreateCommand' to run commands after the container is created.
 	"postCreateCommand": "apt-get update && apt-get install -y git && make install"
+
 	// Uncomment to connect as a non-root user. See https://aka.ms/vscode-remote/containers/non-root.
 	// "remoteUser": "vscode"
 }