Merge pull request #80 from runatlantis/envvars

Allow specifying config values as environment variables

README.md

@@ -442,10 +442,10 @@ If you'd like to test out Atlantis before running it on your own repositories yo
 	- `atlantis apply` will run `terraform apply`. Since our pull request creates a `null_resource` (which does nothing) this is safe to do.
 
 ## Server Configuration
-Atlantis configuration can be specified via command line flags or a YAML config file.
-The `gh-token` and `gitlab-token` flags can also be specified via the `ATLANTIS_GH_TOKEN` and `ATLANTIS_GITLAB_TOKEN` environment variables respectively.
+Configuration for `atlantis server` can be specified via command line flags, environment variables or a YAML config file.
 Config file values are overridden by environment variables which in turn are overridden by flags.
 
+### YAML
 To use a yaml config file, run atlantis with `--config /path/to/config.yaml`.
 The keys of your config file should be the same as the flag, ex.
 ```yaml
@@ -454,6 +454,10 @@ gh-token: ...
 log-level: ...
 ```
 
+### Environment Variables
+All flags can be specified as environment variables. You need to convert the flag's `-`'s to `_`'s, uppercase all the letters and prefix with `ATLANTIS_`.
+For example, `--gh-user` can be set via the environment variable `ATLANTIS_GH_USER`.
+
 To see a list of all flags and their descriptions run `atlantis server --help`
 
 ## AWS Credentials

cmd/server.go

@@ -61,7 +61,7 @@ var stringFlags = []stringFlag{
 	},
 	{
 		name:        ConfigFlag,
-		description: "Path to config file.",
+		description: "Path to config file. All flags can be set in a YAML config file instead.",
 	},
 	{
 		name:        DataDirFlag,
@@ -80,15 +80,13 @@ var stringFlags = []stringFlag{
 	{
 		name:        GHTokenFlag,
 		description: "GitHub token of API user. Can also be specified via the ATLANTIS_GH_TOKEN environment variable.",
-		env:         "ATLANTIS_GH_TOKEN",
 	},
 	{
 		name: GHWebHookSecret,
 		description: "Secret used to validate GitHub webhooks (see https://developer.github.com/webhooks/securing/)." +
 			" SECURITY WARNING: If not specified, Atlantis won't be able to validate that the incoming webhook call came from GitHub. " +
 			"This means that an attacker could spoof calls to Atlantis and cause it to perform malicious actions. " +
 			"Should be specified via the ATLANTIS_GH_WEBHOOK_SECRET environment variable.",
-		env: "ATLANTIS_GH_WEBHOOK_SECRET",
 	},
 	{
 		name:        GitlabHostnameFlag,
@@ -102,15 +100,13 @@ var stringFlags = []stringFlag{
 	{
 		name:        GitlabTokenFlag,
 		description: "GitLab token of API user. Can also be specified via the ATLANTIS_GITLAB_TOKEN environment variable.",
-		env:         "ATLANTIS_GITLAB_TOKEN",
 	},
 	{
 		name: GitlabWebHookSecret,
 		description: "Optional secret used to validate GitLab webhooks." +
 			" SECURITY WARNING: If not specified, Atlantis won't be able to validate that the incoming webhook call came from GitLab. " +
 			"This means that an attacker could spoof calls to Atlantis and cause it to perform malicious actions. " +
 			"Should be specified via the ATLANTIS_GITLAB_WEBHOOK_SECRET environment variable.",
-		env: "ATLANTIS_GITLAB_WEBHOOK_SECRET",
 	},
 	{
 		name:        LogLevelFlag,
@@ -156,7 +152,6 @@ type stringFlag struct {
 	name        string
 	description string
 	value       string
-	env         string
 }
 type intFlag struct {
 	name        string
@@ -203,12 +198,9 @@ func (d *DefaultServerCreator) NewServer(userConfig server.UserConfig, config se
 // Init returns the runnable cobra command.
 func (s *ServerCmd) Init() *cobra.Command {
 	c := &cobra.Command{
-		Use:   "server",
-		Short: "Start the atlantis server",
-		Long: `Start the atlantis server
-
-Flags can also be set in a yaml config file (see --` + ConfigFlag + `).
-Config file values are overridden by environment variables which in turn are overridden by flags.`,
+		Use:           "server",
+		Short:         "Start the atlantis server",
+		Long:          `Start the atlantis server and listen for webhook calls.`,
 		SilenceErrors: true,
 		SilenceUsage:  s.SilenceOutput,
 		PreRunE: s.withErrPrint(func(cmd *cobra.Command, args []string) error {
@@ -218,6 +210,14 @@ Config file values are overridden by environment variables which in turn are ove
 			return s.run()
 		}),
 	}
+
+	// Configure viper to accept env vars prefixed with ATLANTIS_ that can be
+	// used instead of flags.
+	s.Viper.SetEnvPrefix("ATLANTIS")
+	s.Viper.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
+	s.Viper.AutomaticEnv()
+	s.Viper.SetTypeByDefaultValue(true)
+
 	// Replace the call in their template to use the usage function that wraps
 	// columns to make for a nicer output.
 	usageWithWrappedCols := strings.Replace(c.UsageTemplate(), ".FlagUsages", ".FlagUsagesWrapped 120", -1)
@@ -232,9 +232,6 @@ Config file values are overridden by environment variables which in turn are ove
 	// Set string flags.
 	for _, f := range stringFlags {
 		c.Flags().String(f.name, f.value, "> "+f.description)
-		if f.env != "" {
-			s.Viper.BindEnv(f.name, f.env) // nolint: errcheck
-		}
 		s.Viper.BindPFlag(f.name, c.Flags().Lookup(f.name)) // nolint: errcheck
 	}