Some notes relating to .gitlab.ci.yml

• if the image is specified at the top it'll be by default used in each stage wherein is no image
• default Gatsby ports: 9000 in serve, 8000 in develop
• gatsby serve & - an ampersand runs the process in the background
• | tac | tac | - is a workaround for an error: (23) Failed writing body https://stackoverflow.com/a/28879552/1521866
• Before deploying a project on Surge, type in a console surge TOKEN. Then go to https://gitlab.com/<username>/<project>/-/settings/ci_cd and create two new environment variables:

Project name -> CI/CD -> Variables -> Add variable

SURGE_LOGIN - email used in the middle of the registration process

SURGE_TOKEN - token provided by the above command

$CI_COMMIT_SHORT_SHA is predefined variable, it'll return the first eight characters of CI_COMMIT_SHA Docs

sed -i "s/%%VERSION%%/$CI_COMMIT_SHORT_SHA" ./public/index.html - sed is a linux command replacing a placeholder (or a marker like %%VERSION%% is placed in index.js file) with a specified key word, in our case it's an environment variable.