Support mapping env vars to multiple settings

lib/convict.js

@@ -163,13 +163,12 @@ function normalizeSchema(name, node, props, fullName, env, argv, sensitive) {
 
   let o = Object.create(node);
   props[name] = o;
-
   // associate this property with an environmental variable
   if (o.env) {
-    if (env[o.env]) {
-      throw new Error("'" + fullName + "' reuses an env variable: " + o.env);
+    if (!env[o.env]) {
+      env[o.env] = [];
     }
-    env[o.env] = fullName;
+    env[o.env].push(fullName);
   }
 
   // associate this property with a command-line argument
@@ -247,9 +246,11 @@ function normalizeSchema(name, node, props, fullName, env, argv, sensitive) {
 
 function importEnvironment(o) {
   Object.keys(o._env).forEach(function(envStr) {
-    let k = o._env[envStr];
     if (process.env[envStr]) {
-      o.set(k, process.env[envStr]);
+      let ks = o._env[envStr];
+      ks.forEach(function(k) {
+        o.set(k, process.env[envStr]);
+      });
     }
   });
 }

test/cases/env_multi.js

@@ -0,0 +1,17 @@
+'use strict';
+
+exports.conf = {
+  foo: {
+    default: 'a',
+    format: String,
+    env: 'FOO'
+  },
+  bar: {
+    default: 'a',
+    format: String,
+    env: 'FOO'
+  },
+};
+exports.env = {
+  FOO: 'b'
+};

test/cases/env_multi.json

@@ -0,0 +1 @@
+{}

test/cases/env_multi.out

@@ -0,0 +1 @@
+{ "foo": "b", "bar": "b" }

test/schema-tests.js

@@ -23,13 +23,6 @@ describe('convict schema file', function() {
     conf = convict(path.join(__dirname, 'cases/schema-built-in-formats.json'));
   });
 
-  it('must throw when parsing a specification that reuses an env variable', function() {
-    (function() { convict({
-      foo: {default: 'a', env: 'BAZ'},
-      bar: {default: 'a', env: 'BAZ'}
-    })}).must.throw();
-  });
-
   it('must throw when parsing a specification that reuses a command-line argument', function() {
     (function() { convict({
       foo: {default: 'a', arg: 'BAZ'},