Add publicly accessible GitHub user SSH public keys to 'authorized_keys'

secs.sh

#!/bin/bash

############################################################
# Script META                                              #
############################################################
MetaName="secs.sh"
MetaDesc="Add publicly accessible GitHub user SSH public keys to 'authorized_keys'"
MetaVersion="2023.6.1"


############################################################
# Helpers                                                  #
# Color, Defaults, ...                                     #
############################################################

# Check if stdout is a terminal
if test -t 1; then

    # Check if it supports colors
    ncolors=$(tput colors)
    if test -n "$ncolors" && test $ncolors -ge 8; then
        BOLD="$(tput bold)"
        UNDERLINE="$(tput smul)"
        STANDOUT="$(tput smso)"
        ENDCOLOR="$(tput sgr0)"
        BLACK="$(tput setaf 0)"
        RED="$(tput setaf 1)"
        GREEN="$(tput setaf 2)"
        YELLOW="$(tput setaf 3)"
        BLUE="$(tput setaf 4)"
        MAGENTA="$(tput setaf 5)"
        CYAN="$(tput setaf 6)"
        WHITE="$(tput setaf 7)"
    fi
fi


# Set variables
Verbose=0
Username=""
KeyDir="$HOME/.ssh"
KeyFile="authorized_keys"
KeyPath="$KeyDir/$KeyFile"

############################################################
# Help                                                     #
############################################################
OfferHelp="See '$MetaName -h' for help"
Help()
{
    # Display Help
    echo $MetaName
    echo $MetaDesc
    echo
    echo "Syntax: $MetaName [-h|V|u]"
    echo "options:"
    echo "-h      Print this Help and exit."
    echo "-V      Print software version and exit."
    echo "-u bob  Specify username"
    echo
    echo "Example: curl -s link-to-$MetaName | bash -s -- -u BoxedBrain"
    echo
}


############################################################
# Version                                                  #
############################################################
Version()
{
    # Display Version
    echo "secs.sh@$(hostname)"
    echo "Version: $MetaVersion" 
    echo "(c) Tobias Nessel"
}


############################################################
# FixPermissions                                           #
# Check and fix file/folder permissions                    #
############################################################
FixPermissions()
{
    # check '~/.ssh' folder permissions
    KeyDirPermissions=$(stat --format '%a' $KeyDir)
    if [[ 700 -ne $KeyDirPermissions ]]
    then
        echo "${YELLOW}WARNING${ENDCOLOR} '${KeyDir}' insecure directory permissions: ${KeyDirPermissions}"
        # fix permissions
        chmod 700 $KeyDir
        error=$?

        if [[ $error -ne 0 ]]
        then
           echo "${RED}ERROR${ENDCOLOR} '${KeyDir}' failed to set directory permissions to 700"
           exit 1
        else
             echo "${GREEN}OK${ENDCOLOR} '${KeyDir}' directory permissions set to 700"
        fi
    else
        [[ 1 -eq $Verbose ]] && echo "'${KeyDir}' permissions: ${KeyDirPermissions}"
    fi

    # check 'authorized_keys' file permissions
    KeyFilePermissions=$(stat --format '%a' $KeyPath)
    if [[ 600 -ne $KeyFilePermissions ]]
    then
        echo "${YELLOW}WARNING${ENDCOLOR} '${KeyPath}' insecure file permissions: ${KeyFilePermissions}"
        # fix permissions
        chmod 600 $KeyPath
        error=$?

        if [[ $error -ne 0 ]]
        then
           echo "${RED}ERROR${ENDCOLOR} '${KeyPath}' failed to set file permissions to 600"
           exit 1
        else
             echo "${GREEN}OK${ENDCOLOR} '${KeyPath}' file permissions set to 600"
        fi
    else
        [[ 1 -eq $Verbose ]] && echo "'${KeyPath}' permissions: ${KeyFilePermissions}"
    fi
}


############################################################
# Process the input options. Add options as needed.        #
############################################################
# Get the options
while getopts ":hVvcu:" option; do
   case $option in
      h) # display Help
         Help
         exit;;
      V) # display Version
         Version
         exit;;
      v) # enable verbose mode
         Verbose=1;;
      c) # create folder or file if missing
         Create=1;;   
      u) # enter username
         Username=$OPTARG;;
     \?) # invalid option
         echo "${RED}ERROR${ENDCOLOR} Invalid option provided"
         echo $OfferHelp
         exit;;
   esac
done


if [ -z $Username ]
then
    echo "${RED}ERROR${ENDCOLOR} Missing argument '-u'"
    echo $OfferHelp
    exit 1
fi

[[ 1 -eq $Verbose ]] && Version

############################################################
############################################################
# Main program                                             #
############################################################
############################################################



# Check if folder and keyfile exist
# Folder
if [[ ! -d $KeyDir ]]
then
    echo "${YELLOW}WARNING${ENDCOLOR} Directory ${KeyDir} does not exist"

    # should we create it?
    if [[ 1 -ne $Create ]]
    then
        echo "Use -c to create it."
        exit 1
    else
        mkdir -p $KeyDir
        error=$?

        # Check for errors
        if [[ $error -ne 0 ]]
        then
           echo "${RED}ERROR${ENDCOLOR} failed to create '${KeyDir}'!"
           exit 1
        else
             echo "${GREEN}OK${ENDCOLOR} directory '${KeyDir}' created"
        fi
    fi    
fi


# File
if [[ ! -f $KeyPath ]]
then
    echo "${YELLOW}WARNING${ENDCOLOR} file '${KeyPath}' does not exist"

    # should we create it?
    if [[ 1 -ne $Create ]]
    then
        echo "Create it first or use parameter ${YELLOW}-c${ENDCOLOR} to create it"
        exit 1
    else
        touch $KeyPath
        error=$?

        # Check for errors
        if [[ $error -ne 0 ]]
        then
           echo "${RED}ERROR${ENDCOLOR} failed to create '${KeyPath}'!"
           exit 1
        else
             echo "${GREEN}OK${ENDCOLOR} file '${KeyPath}' created"
        fi
    fi   
fi

# Check for permission issues
FixPermissions

# get existing authorized SSH keys
ExistingUserKeys=$(cat $KeyPath)

[[ 1 -eq $Verbose ]] && echo -e "Current installed keys: \n ${ExistingUserKeys}"

# get available GitHub SSH keys for given user

NewKeys=$(curl -s --fail https://github.com/$Username.keys)
error=$?

if [[ $error -ne 0 ]]
then
    echo "${RED}ERROR${ENDCOLOR} getting keys for '$Username'! Check username and network connection."
    exit 1
fi

[[ 1 -eq $Verbose ]] && echo -e "New keys: \n ${NewKeys}"

# add new keys if not already existing
IFS=$'\n'
CountTotal=0
CountNew=0
for NewKey in $NewKeys
do
    CountTotal=$((CountTotal+1))
    if [[ "$ExistingUserKeys" != *"$NewKey"* ]]; then
        [[ 1 -eq $Verbose ]] && echo $NewKey
        echo $NewKey >> $KeyPath
        CountNew=$((CountNew+1))
    fi
done

echo "Total: ${YELLOW}$CountTotal${ENDCOLOR} New: ${GREEN}$CountNew${ENDCOLOR}"
exit 0

Run in a terminal:

curl -s https://gist.githubusercontent.com/BoxedBrain/d01fcdfcf00db947cf4780134faae89a/raw/secs.sh | bash -s -- -u <username>

Run inside a docker container:

docker exec <container> bash -c 'curl -s https://gist.githubusercontent.com/BoxedBrain/d01fcdfcf00db947cf4780134faae89a/raw/secs.sh | bash -s -- -u <username> -vc'