merge-request.sh

#!/usr/bin/env bash
set -e

if [ -z "$GITLAB_PRIVATE_TOKEN" ]; then
  echo "GITLAB_PRIVATE_TOKEN not set"
  echo "Please set the GitLab Private Token as GITLAB_PRIVATE_TOKEN"
  exit 1
fi

source set-target-branch.sh

# Conditional commit prefix, etc: WIP
if [ -z "${COMMIT_PREFIX}" ]; then
  COMMIT_TITLE="${CI_COMMIT_REF_NAME}"
else
  COMMIT_TITLE="${COMMIT_PREFIX}: ${CI_COMMIT_REF_NAME}"
fi

# Conditional remove branch after merge
if [ -z "${REMOVE_BRANCH_AFTER_MERGE}" ]; then
  REMOVE_BRANCH_AFTER_MERGE=false
fi

# Conditional squash after merge
if [ -z "${SQUASH}" ]; then
  SQUASH=false
fi

# Conditional auto merge
# if [ -z "${AUTO_MERGE}" ]; then
#   AUTO_MERGE=false
# fi

# Extract the host where the server is running, and add the URL to the APIs
[[ $CI_PROJECT_URL =~ ^https?://[^/]+ ]] && HOST="${BASH_REMATCH[0]}/api/v4/projects/"

if [ -z "$TARGET_BRANCH" ]; then
  echo "TARGET_BRANCH not set"
  if [ -z "$FALLBACK_TARGET_BRANCH" ]; then
    echo "Using Default branch to open the Merge request"
    # Look which is the default branch
    echo "HOST: ${HOST}"
    echo "Project ID: ${CI_PROJECT_ID}"
    TARGET_BRANCH=`curl --silent "${HOST}${CI_PROJECT_ID}" --header "PRIVATE-TOKEN:${GITLAB_PRIVATE_TOKEN}" | jq --raw-output '.default_branch'`;
  else
    echo "Using FALLBACK_TARGET_BRANCH branch to open the Merge request"
    TARGET_BRANCH="${FALLBACK_TARGET_BRANCH}"
  fi
fi

echo "Source: ${CI_COMMIT_REF_NAME}"
echo "Target: ${TARGET_BRANCH}"

# If Source and Target branch is same then exit.
if [ "${CI_COMMIT_REF_NAME}" = "${TARGET_BRANCH}" ]; then
  echo "Source and Target branch is must be different! Exiting!"
  exit 0
fi

# The description of our new MR, we want to remove the branch after the MR has
# been closed
BODY="{
    \"id\": ${CI_PROJECT_ID},
    \"source_branch\": \"${CI_COMMIT_REF_NAME}\",
    \"target_branch\": \"${TARGET_BRANCH}\",
    \"squash\": \"${SQUASH}\",
    \"title\": \"${COMMIT_TITLE}\",
    \"assignee_id\":\"${GITLAB_USER_ID}\"
}";
#

# Require a list of all the merge request and take a look if there is already
# one with the same source branch
LISTMR=`curl --silent "${HOST}${CI_PROJECT_ID}/merge_requests?state=opened" --header "PRIVATE-TOKEN:${GITLAB_PRIVATE_TOKEN}"`;
COUNTBRANCHES=`echo ${LISTMR} | grep -o "\"source_branch\":\"${CI_COMMIT_REF_NAME}\"" | wc -l`;

echo "No MR found, let's create a new one"
# No MR found, let's create a new one
if [ ${COUNTBRANCHES} -eq "0" ]; then
    echo 80
    echo ${BODY}
    
    response=`curl --silent -X POST "${HOST}${CI_PROJECT_ID}/merge_requests" \
            --header "PRIVATE-TOKEN:${GITLAB_PRIVATE_TOKEN}" \
            --header "Content-Type: application/json" \
            --data "${BODY}"`;

    echo $response
    IID=`echo $response | jq .\"iid\"`
    echo $IID
    echo "Opened a new merge request: ${COMMIT_TITLE} and assigned with id ${IID}";

    if $AUTO_MERGE; then
      BODY="{
          \"merge_when_pipeline_succeeds\": \"true\",
          \"squash\": \"${SQUASH}\"
      }";
      #\"should_remove_source_branch\": \"${REMOVE_BRANCH_AFTER_MERGE}\",

      curl --silent -X PUT "${HOST}${CI_PROJECT_ID}/merge_requests/${IID}/merge" \
            --header "PRIVATE-TOKEN:${GITLAB_PRIVATE_TOKEN}" \
            --header "Content-Type: application/json" \
            --data "${BODY}";
           
      printf "\n"
      echo "Auto merging requested for ${COMMIT_TITLE} with id ${IID}";
    fi
    exit;
fi

echo "No new merge request opened";