Go runs

A Go run compiles and runs a program with go run. The source is the run's command, a full package main program with a func main. It suits a task that wants Go's type safety or an existing Go snippet: calling an API, reshaping data, or a quick check that a shell script would strain to express.

What runs

The source is written to a temporary main.go and run with go run, so a whole program builds and runs in one step. The working directory is the project checkout when the run sources a project. A dry run runs go vet, which compiles and statically checks the source without executing it. The dry run reports whether it found problems, so a clean check does not leave an empty log.

Two things to know. A program that imports only the standard library runs with no setup. Third-party imports need a module, the same constraint go run places on a single file. And go run reports its own exit code, one on any program failure, not the value passed to os.Exit, so a failing run shows exit one with exit status N in the log.

How values reach the program

• Extra vars, including survey answers and template vars, arrive as YARDMASTER_VARS, a JSON object:

    var vars map[string]any
    _ = json.Unmarshal([]byte(os.Getenv("YARDMASTER_VARS")), &vars)
    region, _ := vars["region"].(string)
  

• An env credential's KEY=VALUE lines are set in the environment, read with os.Getenv.

• A token credential is set as YARDMASTER_TOKEN, ready to send as a bearer token.

• Credentials attached to the run's inventory arrive the same way.

Example

package main

import (
    "encoding/json"
    "net/http"
    "os"
)

func main() {
    var vars map[string]any
    _ = json.Unmarshal([]byte(os.Getenv("YARDMASTER_VARS")), &vars)
    service, _ := vars["service"].(string)
    req, _ := http.NewRequest(http.MethodPost, "https://api.example.com/deploy/"+service, nil)
    req.Header.Set("Authorization", "Bearer "+os.Getenv("YARDMASTER_TOKEN"))
    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        os.Exit(1)
    }
    os.Stdout.WriteString(resp.Status)
}

See also Bash runs, Terraform runs, Python runs, and the tutorials.