slack text notifications

.gitlab-ci.yml

 SLACK_TEXT_START: 'Pipeline <$CI_PIPELINE_URL|$CI_PIPELINE_ID> _has started_  *$CI_PIPELINE_SOURCE* job <$CI_JOB_URL|$CI_JOB_ID> on *$ENVIRONMENT* _at branch_ *<$CI_PROJECT_URL/commit/$CI_COMMIT_SHA|$CI_COMMIT_REF_NAME>*'
 SLACK_TEXT_FINISH: 'Pipeline <$CI_PIPELINE_URL|$CI_PIPELINE_ID> _has finished_ *$CI_PIPELINE_SOURCE* job <$CI_JOB_URL|$CI_JOB_ID> on *$ENVIRONMENT* _at branch_ *<$CI_PROJECT_URL/commit/$CI_COMMIT_SHA|$CI_COMMIT_REF_NAME>* _and generated_ *<$ALLURE_DIR|Allure Reports>*'
 
 #####################################
#  Custom Slack POST-message report #
#####################################
slack_notification:
  script:
    - >
      curl
      --request POST
      --data-urlencode
      "payload={
        \"channel\":\"$SLACK_CHANNEL\",
        \"username\":\"$SLACK_USER\",
        \"text\":\"$SLACK_TEXT_FINISH\",
        \"icon_emoji\":\":gitlab:\"
      }"
      https://hooks.slack.com/services/$SLACK_TOKEN