Merge ~pwlars/testflinger-cli:server-env into testflinger-cli:master

[Paul Larson]

Allow server to be specified with environment variable

[Maciej Kisielewski (kissiel)]

LGTM +1

review: Approve

diff --git a/README.rst b/README.rst
index 4ab1f4b..58ad977 100644
--- a/README.rst
+++ b/README.rst
@@ -36,6 +36,9 @@ After installing testflinger-cli, you can get help by just running
 To specify a different server to use, you can use the '--server'
 parameter, otherwise it will default to the one running on
 http://testflinger.canonical.com
+You may also set the environment variable 'TESTFLINGER_SERVER' to
+the URI of your server, and it will prefer that over the default
+or the string specified by --server.
 
 To submit a new test job, first create a yaml or json file containing
 the job definition. Then run:
diff --git a/testflinger-cli b/testflinger-cli
index 3c071f5..d51b4f2 100755
--- a/testflinger-cli
+++ b/testflinger-cli
@@ -36,6 +36,9 @@ if os.path.exists(os.path.join(basedir, 'setup.py')):
               help='Testflinger server to use')
 @click.pass_context
 def cli(ctx, server):
+    env_server = os.environ.get('TESTFLINGER_SERVER')
+    if env_server:
+        server = env_server
     ctx.obj['conn'] = testflinger_cli.Client(server)