Hof can generate data files during code generation. Create any JSON, Yaml, XML, Toml and CUE file from a single source of truth CUE configuration and schemas. Use existing data and configurations as part of the input if you already have a source of truth.
Ad hoc generation
In CUE you can output a single data file at a time:
cue export config.yaml schema.cue -e app -O app.yaml cue export config.yaml schema.cue -e helm -O values.yaml
However this can become unweildy for large numbers of files or when you want to do more complex things with CUE.
With hof ad hoc generation, you can output multiple files in one command.
hof gen config.yaml config.cue \ -T :stg.app=app.yaml \ -T :stg.helm=values.yaml
Here, we have generated the application configuration and helm input values for the staging deployment of our application. We use an existing Yaml file, apply a CUE schema, set defaults, or otherwise validate or transform the inputs.
config.yaml- existing or minimal configuration
config.cue- a CUE file where we can apply schemas or transformations
-T <template>:<cue-path>=<outfile-name>is a template, or a data file in this case
-T :<...>leaves off the template, telling hof this is a data file
<cue-path>is any valid CUE path to subselect a field within the larger CUE value
<outfile-name>is any valid data type, hof will infer the format from the extension
[put an example here]
When supplying one more more data files during input,
you can tell hof where to put a data file in the CUE value
by using the
hof gen firstname.lastname@example.org \ email@example.com \ schema.cue \ -T :stg.app=app.yaml \ -T :stg.helm=values.yaml
You can have local app config combined with organization wide values to generate the inputs for multiple tools and workflows. You can intermix existing data with CUE throughout the software stack and life-cycle.
Even hof’s commands will get cumbersome when you want to generate many files. You can use generators to reduce the complexity of the commands.
hof generators can be package as modules, dependency managed, and give you reusable bundles of CUE and hof. When authoring a module, you can use the data file features to capture commands like we just saw into code. We can then shorten our commands significantly.
hof gen app.cue -t env=stg
When you configure a data file for output in your generator configuration, the fields you set are different.
Valis the input value, instead of
DatafileFormattells hof to generate data and what format
Filepathfor where to write the file
Users then run
hof gen app.cue [-t env=stg]
[Links to infra generator module]