#!/usr/bin/env bash
#-------------------------------------------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See https://go.microsoft.com/fwlink/?linkid=2090316 for license information.
#-------------------------------------------------------------------------------------------------------------

# Syntax: ./docker-debian.sh [enable non-root docker socket access flag] [source socket] [target socket] [non-root user]

ENABLE_NONROOT_DOCKER=${1:-"true"}
SOURCE_SOCKET=${2:-"/var/run/docker-host.sock"}
TARGET_SOCKET=${3:-"/var/run/docker.sock"}
USERNAME=${4:-"vscode"}

set -e

if [ "$(id -u)" -ne 0 ]; then
    echo -e 'Script must be run a root. Use sudo, su, or add "USER root" to your Dockerfile before running this script.'
    exit 1
fi

# Function to run apt-get if needed
apt-get-update-if-needed()
{
    if [ ! -d "/var/lib/apt/lists" ] || [ "$(ls /var/lib/apt/lists/ | wc -l)" = "0" ]; then
        echo "Running apt-get update..."
        apt-get update
    else
        echo "Skipping apt-get update."
    fi
}

# Ensure apt is in non-interactive to avoid prompts
export DEBIAN_FRONTEND=noninteractive

# Install apt-transport-https, curl, lsb-release, gpg if missing
if ! dpkg -s apt-transport-https curl ca-certificates lsb-release > /dev/null 2>&1 || ! type gpg > /dev/null 2>&1; then
    apt-get-update-if-needed
    apt-get -y install --no-install-recommends apt-transport-https curl ca-certificates lsb-release gnupg2 
fi

# Install Docker CLI if not already installed
if type docker > /dev/null 2>&1; then
    echo "Docker CLI already installed."
else
    curl -fsSL https://download.docker.com/linux/$(lsb_release -is | tr '[:upper:]' '[:lower:]')/gpg | (OUT=$(apt-key add - 2>&1) || echo $OUT)
    echo "deb [arch=amd64] https://download.docker.com/linux/$(lsb_release -is | tr '[:upper:]' '[:lower:]') $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list
    apt-get update
    apt-get -y install --no-install-recommends docker-ce-cli
fi

# Install Docker Compose if not already installed 
if type docker-compose > /dev/null 2>&1; then
    echo "Docker Compose already installed."
else

    LATEST_COMPOSE_VERSION=$(curl -sSL "https://api.github.com/repos/docker/compose/releases/latest" | grep -o -P '(?<="tag_name": ").+(?=")')
    curl -sSL "https://github.com/docker/compose/releases/download/${LATEST_COMPOSE_VERSION}/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
    chmod +x /usr/local/bin/docker-compose
fi

# If init file already exists, exit
if [ -f "/usr/local/share/docker-init.sh" ]; then
    exit 0
fi

# By default, make the source and target sockets the same
if [ "${SOURCE_SOCKET}" != "${TARGET_SOCKET}" ]; then
    touch "${SOURCE_SOCKET}"
    ln -s "${SOURCE_SOCKET}" "${TARGET_SOCKET}"
fi

# Add a stub if not adding non-root user access, user is root, or the specified user does not exist
if [ "${ENABLE_NONROOT_DOCKER}" = "false" ] || [ "${USERNAME}" = "root" ] || ! id -u ${USERNAME} > /dev/null 2>&1; then
    echo '/usr/bin/env bash -c "\$@"' > /usr/local/share/docker-init.sh
    chmod +x /usr/local/share/docker-init.sh
    exit 0
fi

# If enabling non-root access and specified user is found, setup socat and add script
chown -h "${USERNAME}":root "${TARGET_SOCKET}"        
if ! dpkg -s socat > /dev/null 2>&1; then
    apt-get-update-if-needed
    apt-get -y install socat
fi
tee /usr/local/share/docker-init.sh > /dev/null \
<< EOF 
#!/usr/bin/env bash
#-------------------------------------------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See https://go.microsoft.com/fwlink/?linkid=2090316 for license information.
#-------------------------------------------------------------------------------------------------------------

set -e

SOCAT_PATH_BASE=/tmp/vscr-dind-socat
SOCAT_LOG=\${SOCAT_PATH_BASE}.log
SOCAT_PID=\${SOCAT_PATH_BASE}.pid

# Wrapper function to only use sudo if not already root
sudoIf()
{
    if [ "\$(id -u)" -ne 0 ]; then
        sudo "\$@"
    else
        "\$@"
    fi
}

# Log messages
log()
{
    echo -e "[\$(date)] \$@" | sudoIf tee -a \${SOCAT_LOG} > /dev/null
}

echo -e "\n** \$(date) **" | sudoIf tee -a \${SOCAT_LOG} > /dev/null
log "Ensuring ${USERNAME} has access to ${SOURCE_SOCKET} via ${TARGET_SOCKET}"

# If enabled, try to add a docker group with the right GID. If the group is root, 
# fall back on using socat to forward the docker socket to another unix socket so 
# that we can set permissions on it without affecting the host.
if [ "${ENABLE_NONROOT_DOCKER}" = "true" ] && [ "${SOURCE_SOCKET}" != "${TARGET_SOCKET}" ] && [ "${USERNAME}" != "root" ] && [ "${USERNAME}" != "0" ]; then
    SOCKET_GID=\$(stat -c '%g' ${SOURCE_SOCKET})
    if [ "\${SOCKET_GID}" != "0" ]; then
        log "Adding user to group with GID \${SOCKET_GID}."
        if [ "\$(cat /etc/group | grep :\${SOCKET_GID}:)" = "" ]; then
            sudoIf groupadd --gid \${SOCKET_GID} docker-host
        fi
        # Add user to group if not already in it
        if [ "\$(id ${USERNAME} | grep -E 'groups=.+\${SOCKET_GID}\(')" = "" ]; then
            sudoIf usermod -aG \${SOCKET_GID} ${USERNAME}
        fi
    else
        # Enable proxy if not already running
        if [ ! -f "\${SOCAT_PID}" ] || ! ps -p \$(cat \${SOCAT_PID}) > /dev/null; then
            log "Enabling socket proxy."
            log "Proxying ${SOURCE_SOCKET} to ${TARGET_SOCKET} for vscode"
            sudoIf rm -rf ${TARGET_SOCKET}
            (sudoIf socat UNIX-LISTEN:${TARGET_SOCKET},fork,mode=660,user=${USERNAME} UNIX-CONNECT:${SOURCE_SOCKET} 2>&1 | sudoIf tee -a \${SOCAT_LOG} > /dev/null & echo "\$!" | sudoIf tee \${SOCAT_PID} > /dev/null)
        else
            log "Socket proxy already running."
        fi
    fi
    log "Success"
fi

# Execute whatever commands were passed in (if any). This allows us 
# to set this script to ENTRYPOINT while still executing the default CMD.
set +e
exec "\$@"
EOF
chmod +x /usr/local/share/docker-init.sh
chown ${USERNAME}:root /usr/local/share/docker-init.sh
echo "Done!"