Provide a flag to pass environment variables at runtime

repo2docker/app.py

@@ -297,6 +297,14 @@ class Repo2Docker(Application):
             help='Username of the primary user in the image',
         )
 
+        argparser.add_argument(
+            '--env', '-e',
+            dest='environment',
+            nargs='+',
+            help='Environment variables to define at container run time',
+            default=[]
+        )
+
         return argparser
 
     def json_excepthook(self, etype, evalue, traceback):
@@ -389,6 +397,12 @@ class Repo2Docker(Application):
         if args.build_memory_limit:
             self.build_memory_limit = args.build_memory_limit
 
+        if args.environment and not self.run:
+            print("To specify environment variables, you also need to run the container")
+            sys.exit(1)
+
+        self.environment = args.environment
+
     def push_image(self):
         client = docker.APIClient(version='auto', **kwargs_from_env())
         # Build a progress setup for each layer, and only emit per-layer
@@ -442,7 +456,8 @@ class Repo2Docker(Application):
             ports=ports,
             detach=True,
             command=run_cmd,
-            volumes=container_volumes
+            volumes=container_volumes,
+            environment=self.environment
         )
         while container.status == 'created':
             time.sleep(0.5)

tests/argumentvalidation.py

@@ -118,4 +118,14 @@ def test_volume_no_run_fail():
     builddir = os.path.dirname(__file__)
     args_list = ['--no-run', '-v', '/data:/data']
 
-    assert not validate_arguments(builddir, args_list, 'To Mount volumes with -v, you also need to run the container')
+    assert not validate_arguments(builddir, args_list, 'To Mount volumes with -v, you also need to run the container')
+
+def test_env_no_run_fail():
+    """
+    Test to check if repo2docker fails when both --no-run and -e arguments are given 
+    """
+    builddir = os.path.dirname(__file__)
+    args_list = ['--no-run', '-e', 'FOO=bar', '--']
+
+    assert not validate_arguments(builddir, args_list, 'To specify environment variables, you also need to run the container')
+

tests/env.py

@@ -0,0 +1,30 @@
+"""
+Test that volume mounts work when running
+"""
+import os
+import subprocess
+import tempfile
+import time
+
+def test_env():
+    """
+    Validate that you can define environment variables
+    """
+    ts = str(time.time())
+    with tempfile.TemporaryDirectory() as tmpdir:
+        username = os.getlogin()
+        subprocess.check_call([
+            'repo2docker',
+            '-v', '{}:/home/{}'.format(tmpdir, username),
+            '-e', 'FOO={}'.format(ts), 'BAR=baz',
+            '--',
+            tmpdir,
+            '/bin/bash',
+            '-c', 'echo -n $FOO > ts && echo -n $BAR > bar'
+        ])
+
+        with open(os.path.join(tmpdir, 'ts')) as f:
+            assert f.read().strip() == ts
+        with open(os.path.join(tmpdir, 'bar')) as f:
+            assert f.read().strip() == 'baz'
+