backport

#!/bin/bash

## Bash script to automate BAISC MongoDB backports.
## Backports to ONE previous (or future) version
## branch at a time. If a conflict is encountered in
## the course of a cherry-pick, notifies the user and
## terminates, else completes the backport and presents
## the user with the relevant PR URL.

## Requirements:
##
## - Must be called from within a git repo
## - Must have committed the change you wish
##   to backport
## - Must be in the appropriate branch, or one of its
##   backport branchs as created by this program

## Supports the following usage:
##
## backport <version>
##     backports commit to specified major version, like:
##         v4.0, v3.6, v3.2
##     or minor revison if to future branches, like:
##         v4.0.14, v3.6.16, v3.4.24
##     or the master branch if "up-porting", like:
##         master
##     where commit message contains the jira ticket that
##     starts your current branchname. Only accepts ONE
##     target version at a time.
## backport resume
##     if previous invocation of this utility met with
##     a conflict in the cherry-pick stage, and you have
##     since manually corrected it, use this to resume
##     the cherry pick and publish as normal. Don't forget
##     to save your changes in VSCode! No need to run
##     git add or git commit, however.
## backport edit
##     if you have already created the PR to the previous
##     branch, wish to make a last minute change, and
##     have not completed the PR in GitHub, you may use
##     this option to edit the PR. Don't forget
##     to save your changes in VSCode! No need to run
##     git add or git commit, however.

############################################################
## YOUR VALUES ##
#################

## Your github username:
GITUSER=your_git_user

############################################################
## BEGIN SCRIPT ##
##################

TMPFILE=/tmp/backport$$.tmp

## Check for provided parameter:
PARAMETER=$1

# Parse user-provided parameter and determine what to do:
if [ -z $PARAMETER ]; then
   echo -e "\nERROR: No parameter provided. You must provide one of:"
   echo -e "     - <vers>: ONE of major version like: v4.0, v3.6, v3.4"
   echo -e "               or minor revision like: v4.0.14, v3.6.16, v3.4.24" 
   echo -e "     - resume: to resume an in-progress backport"
   echo -e "     - edit: to edit an already pushed backport"
   echo -e "       Exiting ...\n"
   exit;
elif [ ! -z $2 ]; then
   echo -e "\nERROR: Too many parameters provided. You must provide one of:"
   echo -e "     - <vers>: ONE of major version like: v4.0, v3.6, v3.4"
   echo -e "               or minor revision like: v4.0.14, v3.6.16, v3.4.24"
   echo -e "     - resume: to resume an in-progress backport"
   echo -e "     - edit: to edit an already pushed backport"
   echo -e "       Exiting ...\n"
   exit;
elif [[ "$PARAMETER" =~ ^(resume|RESUME|Resume)$ ]]; then
   RESUME=1
   echo "Resuming existing cherry-pick ..."
elif [[ "$PARAMETER" =~ ^(edit|EDIT|Edit)$ ]]; then
   EDIT=1
   echo "Editing existing backport ..."
elif [[ "$PARAMETER" =~ ^(master|MASTER|master)$ ]]; then
   TARGETVERS="master"
elif [ `echo $PARAMETER | sed 's%^v%%g' | egrep -c '^[0-9]\.[0-9]{1,2}\.{0,1}[0-9]{0,2}$'` -lt 1 ]; then
   echo -e "\nERROR: Invalid backport version provided."
   echo -e "       Must be ONE of major version like: v4.0, v3.6, v3.4"
   echo -e "       or minor revision like: v4.0.14, v3.6.16, v3.4.24"
   echo -e "       This script only supports one backport at a time."
   echo -e "       Exiting ...\n"
   exit;
else
   TARGETVERS=$PARAMETER
fi

# Determine BRANCHNAME:
BRANCHNAME=`git rev-parse --abbrev-ref HEAD 2>&1`

## Exit if not in a valid git repo:
if [ `echo $BRANCHNAME | grep -c '^fatal: not a git repository'` -gt 0 ]; then
   echo -e "\nERROR: Not in a git repo!"
   echo -e "       Aborting...\n"
   exit;
fi

## IF RESUMING OR EDITING:
if [[ ! -z $RESUME || ! -z $EDIT ]]; then

   ## Sanity check: did we forget to resolve any conflicts?
   grep -R '<<<<<<< HEAD' source/* | awk -F':' '{print $1}' | sort -u > $TMPFILE.missed

   ## If so, notify the user and abort!
   if [ -s $TMPFILE.missed ]; then
      echo -e "\nWARNING: Conflicts still detected in the following file(s):\n"
      echo -e "#############################################################"
      cat $TMPFILE.missed
      echo -e "#############################################################"
      echo -e "\nAborting...\n"
      rm -f $TMPFILE.*
      exit;
   fi

   ## We no longer have a user-provided $PARAMETER,
   ## but can now determine $TARGETVERS directly via git:
   TARGETVERS=`git rev-parse --abbrev-ref --symbolic-full-name @{u} | awk -F'/' '{print $2}'`

   ## Get exiting GIT_EDITOR, to restore later:
   OLD_GIT_EDITOR=`echo $GIT_EDITOR`

   ## Set custom giteditor_autoamend as GIT_EDITOR:
   export GIT_EDITOR=giteditor_autoamend

   git status
   git add source/*

   if [ ! -z $RESUME ]; then
      # Performing a $RESUME:
      git cherry-pick --continue
   else
      # Must be an $EDIT then:
      git commit --amend
   fi

   git pull --rebase
   git push -f origin $BRANCHNAME

   # Build URL:
   PR_URL="https://github.com/mongodb/docs/compare/$TARGETVERS...andf-mongodb:$BRANCHNAME?expand=1"

   # Provide links (clickable in VS Code and iTerm2):
   echo -e "\n##############################  BACKPORT READY!  #############################"
   echo -e "\n      PULL REQUEST: $PR_URL"
   echo -e "\n##############################################################################\n"

   # Replace GIT_EDITOR with original value:
   GIT_EDITOR=`echo $OLD_GIT_EDITOR`

   rm -f $TMPFILE.*
   exit;
fi

## IF NOT RESUMING OR EDITING, check current branch:
## - If branch does not start with $JIRA, likely in different backport branch
##   (like v4.0, etc). Switch to parent branch containing original commit
## - If branch does start with $JIRA, continue as normal.
if [ `echo $BRANCHNAME | awk -F\- '{print $1}' | sed 's%^v%%g' | egrep -c '^[0-9]\.[0-9]{1,2}\.{0,1}[0-9]{0,2}$'` -eq 1 ]; then
   SWITCHTO_JIRA=`echo $BRANCHNAME | awk -F\- '{print $2"-"$3}'`
   SWITCHTO_BRANCH=`git for-each-ref refs/heads | cut -d/ -f3- | grep ^$SWITCHTO_JIRA`
   git checkout $SWITCHTO_BRANCH
   BRANCHNAME=$SWITCHTO_BRANCH
fi

## Determine commit to backport. Only handles one at a time:
JIRA=`echo $BRANCHNAME | awk -F\- '{print $1"-"$2}'`
COMMIT_LINE=`git log --pretty=format:'%h | %s %d' | grep $JIRA`
COMMIT=`echo $COMMIT_LINE | awk -F' | ' {'print $1'}`

if [ -z $COMMIT ]; then
   echo -e "\nERROR: Could not determine commit to backport!"
   echo -e "       You must have committed your fix in order to backport"
   echo -e "       Aborting...\n"
   exit;
fi

## Perform work:
git checkout -b $TARGETVERS-$JIRA upstream/$TARGETVERS
git pull --rebase
git cherry-pick $COMMIT 2>&1 | tee $TMPFILE.out 2>&1 > /dev/null

## Determine if there is a conflict:
if [ `grep -c 'error: could not apply' $TMPFILE.out` -gt 0 ]; then
   echo -e "\nALERT: CONFLICTS DETECTED"
   echo -e "       You must now manually correct conflicts."
   echo -e "       When ready, use 'backport resume' to return to this step."
   echo -e "       Exiting...\n"
   rm -f $TMPFILE.*
   exit;
else
   echo -e "\nNo conflicts detected! Huzzah!"
   echo -e "       Continuing ...\n"
fi

git pull --rebase
git push -f origin $TARGETVERS-$JIRA

# Build URL:
PR_URL="https://github.com/mongodb/docs/compare/$TARGETVERS...andf-mongodb:$TARGETVERS-$JIRA?expand=1"

# Provide links (clickable in VS Code and iTerm2):
echo -e "\n##############################  BACKPORT READY!  #############################"
echo -e "\n      PULL REQUEST: $PR_URL"
echo -e "\n##############################################################################\n"

rm -f $TMPFILE.*