catalystcommunity / service-go-hello-api

repository for a golang cobra cli application with configuration via viper

service-go-hello-api

This is the service implementation for the api for hello world

Features

• Implementation via Cobra
• Configuration via Viper
• Error handling via the Catalyst Platform Utils library which includes support for sentry
• Utilities from catalyst squad such as logging via logrus
• Command configuration validation via Go validator
• Basic skaffold.yaml included
• Basic non-root Dockerfile included
• Github workflows for release and image uploading included

FAQ

How do I add a new command?

You can do it manually by adding a new .go file in the cmd directory, but I'd recommend using the cobra cli generator

1. Install the generator globally with go install github.com/spf13/cobra-cli@latest
2. Run cobra-cli add myCommand. This will generate a new go file and the skeleton for your new command.
3. Add your flags if any in the init() method. See cmd/example.go for an example
4. Add your config struct with validators
5. Implement your run function. If you have config, make sure you call GetConfigFromViper(config) in the run function, it will not work in the init() function.
6. See cmd/example.go for an example

How do the flags and viper work together?

Viper's global config is configured in cmd/root.go#initConfig(). We're using it to attempt to read configuration files as well as calling viper.AutomaticEnv() which will bind environment variables to flags when viper.BindPFlags(flags) is called

Binding flags should be done in each command's init() function. Calling viper.BindPFlags(flags) binds whatever configuration viper has found to viper. That could be a .yaml file, or env vars, or cli flags like --my_flag, this call makes viper aware of the flags and configs.

Why should I use _ instead of - in my flag names?

Simplicity. If your flag names are all strings separated with _ then you can simply use an identically named environment variable to set the setting. If you use - then there's other viper config and trickery you have to do to get it to read the env vars correctly. We don't believe it's worth the extra stuff, just use _ and it works well out of the box.

HALP

If you need more help, create an issue, or reference the more detailed linked documentation to all the components comprising this app

Running locally

The easiest way to run locally is with skaffold. Have a local cluster of your choice and run:

skaffold dev --tolerate-failures-until-deadline=true

If you want to run it locally without that, you just need to have the DATABASE_URI env var set appropriately (see tests for a testing example) and a postgres database running somewhere at that URI