A (dirty) bash script that will backup issues from the GitHub repo using API. It takes pagination into consideration. Originally created by @boombatower, improved by @bojanpopic, them improved by me to handle number of pages automatically.

backup_github_issues.sh

#!/bin/bash
# based on the script by Bojan Popic https://gist.github.com/bojanpopic/2c3025d2952844de1dd0

# Gets all issues form a repo. Since Pull Requests are also Issues in Github internally, these are also included.

repo="organization/repoName"            # put the name of the repo here. Usually it is like this: organization/repo-na$
username="myuser"                       # your github username
password="mypassword"                   # your github password
# this script can be used on public repos with any user's credentials, you don't have to own the repo!

    # -I will give back only the headers without the data
    numberofpages=$( curl -I -u "$username:$password" \
                   "https://api.github.com/repos/$repo/issues?per_page=100&state=all" \
                  | grep last | cut -d"=" -f8 | cut -f1 -d">" )
    # the human logic behind these greps and cuts is: look for the "last" keyword in the output, 
    # the number of pages is a few characters behind it, between a '=' and a '>'
    
    echo
    echo "Getting ${numberofpages} pages of issues..."
    echo
    echo

    for i in `eval echo {1..$numberofpages}`
    do
       filename=$(echo "$repo-issues-page$i.json" | tr / -)
       curl -u $username:$password \
              "https://api.github.com/repos/$repo/issues?per_page=100&state=all&filter=all&page=$i" \
              > $filename
       echo
       echo "Page $i/$numberofpages retrieved, saved as $filename"
       echo
    done