BOSH_ENVIRONMENT and BOSH_DEPLOYMENT are used

Flags override envvars, just like in the bosh cli. `bosh is` users
rejoice.

complete.go

@@ -25,6 +25,13 @@ type compContext struct {
 	Switches []string
 }
 
+func (c *compContext) InsertIfEnvvar(envvar, flag string) {
+	val := os.Getenv(envvar)
+	if val != "" {
+		c.Flags[flag] = append(c.Flags[flag], val)
+	}
+}
+
 func (c compContext) Complete() ([]string, error) {
 	var compFn compFunc
 
@@ -151,5 +158,14 @@ func parseContext(args []string) compContext {
 		}
 	}
 
+	//Flags override environment variables, so put in env vars last... they would
+	// become the second flag value, which is typically ignored in the code
+	ret.InsertIfEnvvar("BOSH_ENVIRONMENT", "--environment")
+	ret.InsertIfEnvvar("BOSH_DEPLOYMENT", "--deployment")
+	ret.InsertIfEnvvar("BOSH_CLIENT", "--client")
+	ret.InsertIfEnvvar("BOSH_CLIENT_SECRET", "--client-secret")
+	ret.InsertIfEnvvar("BOSH_NON_INTERACTIVE", "--non-interactive")
+	ret.InsertIfEnvvar("BOSH_CA_CERT", "--ca-cert")
+
 	return ret
 }

testing.sh

@@ -0,0 +1,3 @@
+make
+unset -f _bosh_comp
+eval "$(./bosh-complete --debug bash-source)"