Variables

Standard Variables

As mentioned before, Boilermaker uses minijinja as its templating engine. This means anything you can do in minijinja, you can do in Boilermaker.

As a quick overview, minijinja (much like Jinja2, Selmer, Django Templates, etc) use the double-brace syntax by default (and as of writing Boilermaker doesn't allow changing this).

Any of the following are valid variable interpolations:

{{ a }}

{{ x.y.z }}

{{ my.vector_of_maps[0].some_key }}

Nested variables

Both boilermaker.toml and any extra vars file allow nested vars. As of writing the command line --var option does not but that may change in the future.

Merging Ruls

Due to how Boilermaker works with minijinja, merges of any variables are shallow.

Given the following:

[project]
...

[variables]
a = 1
b = true
c = { d = { e = "f" }}

[variables.profiles.override-c]
c = { x = { y = "z" } }

Calling boil new TEMPLATE --profile override-c means that you would have the following context:

a = 1
b = true
c = { x = { y = "z" } }

Note that c now contains x.y, not d.e. This is a shallow merge.

Variable Profiles

So, let's say we have the following boilermaker.toml:

[project]
...

[variables]
a = 1
b = 2
c = -1

[variables.profiles.one]
c = 3

[variables.profiles.two]
a = 4
b = 5
c = { d = { e = "f" } }

We would get the following contexts when using these profiles:

Profile "one"

boil new TEMPLATE -p one

produces:

a = 1
b = 2
c = 3  # <- Note that `c` is now a different value.

Profile "two"

boil new TEMPLATE -p two

produces:

a = 4  # <- `a` is overridden
b = 5  # <- `b` is overridden
c = { d = { e = "f" } }  # <- `c` is completely changed in type and all