Add support for git-xargs registered environment variables based on arguments and flags (#127)

* Register env vars based on arguments and flags

Closes #115

These changes add support for git-xargs registered environment variables
based on arguments and flags intended for use by the commands and
scripts called by git-xargs.  These environment variables start with
`XARGS_` to avoid collision with other use cases and include:

- `XARGS_REPO_NAME`: the name of the repository targeted
- `XARGS_DRY_RUN`: whether `--dry-run` flag was provided

Additionally, these changes contain a basic test to ensure this feature
works as expected going forward.

* README documentation, repository owner env var

While updating documentation, I realized that the original intent of
issue 115 might require the repository owner information as well as the
repository name.  This expands the initial changes and performs some
minor refactoring.

Author: andyfeller

README.md

@@ -237,6 +237,16 @@ git-xargs --github-org my-github-org \
   "$(pwd)/scripts/my-ruby-script.rb"
 ```
 
+## Using `git-xargs` environment variables in commands or scripts
+
+When executing commands or scripts, `git-xargs` will register the following environment variables for use by commands or scripts based on the arguments and flags provided:
+
+| Env var            | Value
+| ------------------ | ---------------------------
+| `XARGS_DRY_RUN`    | Whether the `--dry-run` flag was provided to `git-xargs`; options are `true`, `false`
+| `XARGS_REPO_NAME`  | Name of the target repository being processed
+| `XARGS_REPO_OWNER` | Owner of the target repository being processed
+
 ## Debugging runtime errors
 
 By default, `git-xargs` will conceal runtime errors as they occur because its log level setting is `INFO` if not overridden by the `--loglevel` flag.

data/test/_testscripts/test-env-vars.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# This script writes some text to stdout and stderr and then exits.
+# This is used to test that git-xargs registers environment variables based on flags and arguments.
+
+echo "XARGS_DRY_RUN=$XARGS_DRY_RUN"
+echo "XARGS_REPO_NAME=$XARGS_REPO_NAME"
+echo "XARGS_REPO_OWNER=$XARGS_REPO_OWNER"

repository/repo-operations.go

@@ -110,6 +110,10 @@ func executeCommandWithLogger(config *config.GitXargsConfig, repositoryDir strin
 
 	cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
 	cmd.Dir = repositoryDir
+	cmd.Env = os.Environ()
+	cmd.Env = append(cmd.Env, fmt.Sprintf("XARGS_DRY_RUN=%t", config.DryRun))
+	cmd.Env = append(cmd.Env, fmt.Sprintf("XARGS_REPO_NAME=%s", repo.GetName()))
+	cmd.Env = append(cmd.Env, fmt.Sprintf("XARGS_REPO_OWNER=%s", repo.GetOwner().GetLogin()))
 
 	logger.WithFields(logrus.Fields{
 		"Repo":      repo.GetName(),

repository/repo-operations_test.go

@@ -2,6 +2,7 @@ package repository
 
 import (
 	"bytes"
+	"fmt"
 	"testing"
 
 	"github.com/gruntwork-io/git-xargs/config"
@@ -50,3 +51,44 @@ func TestExecuteCommandWithLogger(t *testing.T) {
 	assert.Contains(t, buffer.String(), "Hello, from STDOUT")
 	assert.Contains(t, buffer.String(), "Hello, from STDERR")
 }
+
+// Test that we can execute a script and that the environment variables are set correctly.
+func TestExecuteCommandWithLoggerWithEnvVars(t *testing.T) {
+	t.Parallel()
+
+	cfg := config.NewGitXargsConfig()
+	cfg.Args = []string{"../data/test/_testscripts/test-env-vars.sh"}
+	repo := getMockGithubRepo()
+
+	var buffer bytes.Buffer
+
+	// Test whether the lack of --dry-run sets environment variable correctly
+	cfg.DryRun = false
+
+	logger := &logrus.Logger{
+		Out:       &buffer,
+		Level:     logrus.TraceLevel,
+		Formatter: new(logrus.TextFormatter),
+	}
+
+	err := executeCommandWithLogger(cfg, ".", repo, logger)
+	assert.NoError(t, err)
+	assert.Contains(t, buffer.String(), "XARGS_DRY_RUN=false")
+	assert.Contains(t, buffer.String(), fmt.Sprintf("XARGS_REPO_NAME=%s", *repo.Name))
+	assert.Contains(t, buffer.String(), fmt.Sprintf("XARGS_REPO_OWNER=%s", *repo.Owner.Login))
+
+	// Test whether --dry-run sets environment variable correctly
+	cfg.DryRun = true
+
+	logger = &logrus.Logger{
+		Out:       &buffer,
+		Level:     logrus.TraceLevel,
+		Formatter: new(logrus.TextFormatter),
+	}
+
+	err = executeCommandWithLogger(cfg, ".", repo, logger)
+	assert.NoError(t, err)
+	assert.Contains(t, buffer.String(), "XARGS_DRY_RUN=true")
+	assert.Contains(t, buffer.String(), fmt.Sprintf("XARGS_REPO_NAME=%s", *repo.Name))
+	assert.Contains(t, buffer.String(), fmt.Sprintf("XARGS_REPO_OWNER=%s", *repo.Owner.Login))
+}