Gitea Upgrade Script

gitea-upgrade.sh

#!/bin/bash

export GOPATH=/home/git/go
export GOROOT=/usr/lib/go-1.10
export PATH=$PATH:$GOROOT/bin:$GOPATH/bin

export GITEAPATH=$GOPATH/src/code.gitea.io/gitea
export OLDGITEAPATH=$GOPATH/src/code.gitea.io/gitea-old

cd /home/git/gitea
git fetch

INSTALLED_VERSION="$(./gitea --version | awk '{print $3}' | grep -oP '.*\-' | sed 's/-.*//g;')"
LATEST_VERSION="$(git describe --tags `git rev-list --tags --max-count=1` | sort -rV | head -1 | sed 's/v//g;')"
LATEST_VERSION_TAG="$(git describe --tags `git rev-list --tags --max-count=1` | sort -rV | head -1)"

UPDATE_CHECK=$(printf "$INSTALLED_VERSION\n$LATEST_VERSION" | sort -n | uniq | wc -l)

if [ $UPDATE_CHECK -gt 1 ]; then
 
  echo "[$(date)] - Stopping gitea service..."
  service gitea stop
  cd /home/git

# Upgrade source and install dependencies

  echo "[$(date)] - Fetching gitea source..."
  cd $GITEAPATH

  # Move old build
  cp gitea $OLDGITEAPATH/gitea-"$INSTALLED_VERSION" &&

  git checkout $LATEST_VERSION_TAG
  echo "[$(date)] - OK" || echo "[$(date)] - Error fetching new source"


  # And rebuild Gitea
  echo "[$(date)] - Building new gitea..."
  TAGS="bindata" make generate build
  echo "[$(date)] - OK" || echo "[$(date)] - Error building gitea"

  chown -R git: /home/git

  service gitea start

# Revert to previous build on error

  if [ $? -ne 0 ]; then
  	mv $GITEAPATH/gitea $OLDGITEAPATH/gitea-broken
  	cp $OLDGITEAPATH/gitea-"$OLDGITEAVERSION" /home/git/gitea
	chown -R git /home/git
	service gitea start
	echo "[$(date)] - Error upgrading gitea, reverting to old version"
	exit 1
  fi

  # Clean up old builds

  cd $OLDGITEAPATH

  while [ `ls -t gitea* | wc -l` -gt 10 ]; do
	  rm `ls -t gitea* | tail -1`;
  done

  cd $GITEAPATH
  echo "[$(date)] - OK - Gitea upgraded to $LATEST_VERSION"

else

	echo "[$(date)] - OK - Latest version $INSTALLED_VERSION already installed"
	exit 0

fi

exit 0

You can enhance this to reduce downtime by postponing service gitea stop to basically do a service gitea restart
The linux kernel keeps the current running binary unrelated to changes in the file system. So this should be save.