(1/5) If you do work with #YAML, you might think its just a bunch of lists and dicts used to store data (configuration). Recently I've been building fairly complex #Gitlab #pipeline to build and deploy #Python app to multi cluster #OpenShift deployment.
Let me gou throuh a ways how you can reuse the code:
(2/5) The easiest are the obvious keywords like `before_script` and `after_script`.
If you want to run commands before (or after) all jobs, all the time, then the easiest way is to simply extract the common code as a before_script or after_script key at the beginning of the config file.
While this does not give you a lot of flexibility, it's a very quick and straightforward way to reuse commands.
(3/5) As a programmer you tend to think of a functions.
And #YAML has #anchors, that are a lot like functions. You can define a block of configuration somewhere and create a reference to it using &. Then, you can use it with *. It is also possible to overload them... I found #Gitlab documentation really helpful: https://docs.gitlab.com/ee/ci/yaml/#anchors
While anchors can be quick to get started with, they do have their downsides. The main one is they only work within the same file.
(4/5) If you want to reuse code across several files, then you can use the `extends` keyword. This works similar to inheritance - you define a "template" job that other jobs can then extend.
Some things to keep in mind regarding extends:
* if the key is a hash it will get merged
* if the key is an array, it will get overridden
(5/5) With `include` you can load external file and if you put this all together with enviroment variables you got a powerfull tool in your hand.
You can create a template that contains hidden jobs (starting with .) that can be extended, it is OK to use #anchors in the sameplate as thay are used within the same file.
This allows you to include the same pipeline for each cluster and define everything just by enviroment variables.
RvK