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Configuration on Cloud Foundry

Since backman usually gets deployed as a container image on Cloud Foundry, and the image contents are frozen, it cannot be configured by providing or modifying a simple configuration file like config.json. In Cloud Foundry the general approach thats recommended to configure your applications is the 12-factor app principle, meaning the use environment variables to configure everything relevant for your app. For backman this would be $BACKMAN_CONFIG.

$BACKMAN_CONFIG

You can set environment variables under the env: section in your backman application manifest.yml or via the CLI with cf set-env .... All we need to do is set an environment variable named BACKMAN_CONFIG, containing the entire JSON document that would otherwise be inside the config.json configuration file. When starting up backman will then read this variable and parse the contents as if it were a configuration file.

Check out the manifest.yml example on how this looks like.

Please consult the main configuration documentation for a detailed description on all possible configuration options.

In addition to $BACKMAN_CONFIG it is also common on Cloud Foundry deployments to make use of the environment variables $BACKMAN_USERNAME, $BACKMAN_PASSWORD and sometimes $BACKMAN_ENCRYPTION_KEY. While the configuration option each of these represent could also be set directly within the configuration file config.json (or rather $BACKMAN_CONFIG in this case), the reason for having them separately is to be able to inject their values during cf push stage and not have them hardcoded beforehand within the configuration itself. This is achieved by making use of the cf CLIs variable substitution feature.

If you have a close look at the provided manifest.yml example, you will see that for both $BACKMAN_USERNAME and $BACKMAN_PASSWORD there are such variable references in there instead of actual values:

...
  env:
    ...
    BACKMAN_USERNAME: ((username))
    BACKMAN_PASSWORD: ((password))
...

This means that during deployment you will then be able to inject the actual values with:
cf push -f manifest.yml --var username=MyUserName --var password=SuperSecretPW12345

Service bindings and their credentials

Just as with any configuration information, in line with the 12-factor app principles service bindings are also configured and thus automatically detected via $VCAP_SERVICES environment variable when backman is running on Cloud Foundry. Any service bindings present within this environment variable will be parsed by backman. The content of $VCAP_SERVICES is set by Cloud Foundry itself, you do not have to define this variable yourself. It will automatically contain any service instances you bind to the backman app, either via cf bind-service ... or by specifying the service instance(s) in the manifest.yml under the services: section.