support github api tokens in get_available_solc_versions

CHANGELOG

@@ -1,6 +1,7 @@
-0.5.0 (unreleased)
+0.5.0
 -----
 
+ - Support for github API tokens via environment var GITHUB_TOKEN
  - Improved verbosity when get_available_solc_versions raises
  - Remove interace flag (was removed from solc in 0.4.0)
  - Raise on clone-bin and formal flags when using 0.5.x

solcx/install.py

@@ -1,6 +1,7 @@
 """
 Install solc
 """
+from base64 import b64encode
 from io import BytesIO
 import os
 from pathlib import Path
@@ -144,14 +145,23 @@ def install_solc_pragma(pragma_string, install=True):
 def get_available_solc_versions(headers=None):
     versions = []
     pattern = VERSION_REGEX[_get_platform()]
+
+    # Github sometimes blocks CI from calling their API, if you are having issues try
+    # saving an API token to the environment variable GITHUB_TOKEN in your build environment
+    # https://github.blog/2013-05-16-personal-api-tokens/
+    if not headers and os.getenv('GITHUB_TOKEN'):
+        auth = b64encode(os.getenv('GITHUB_TOKEN').encode()).decode()
+        headers = {'Authorization': "Basic {}".format(auth)}
+
     data = requests.get(ALL_RELEASES, headers=headers)
     if data.status_code != 200:
         raise ConnectionError(
-            "{} when getting solc versions from Github: '{}'".format(
+            "Status {} when getting solc versions from Github: '{}'".format(
                 data.status_code,
                 data.json()['message']
             )
         )
+
     for release in data.json():
         asset = next((i for i in release['assets'] if re.match(pattern, i['name'])), False)
         if asset:

tests/conftest.py

@@ -1,7 +1,5 @@
 #!/usr/bin/python3
 
-from base64 import b64encode
-import os
 import pytest
 import sys
 
@@ -10,9 +8,7 @@
 if sys.platform == "darwin":
     VERSIONS = solcx.get_installed_solc_versions()
 else:
-    auth = b64encode(os.environ['GITAUTH'].encode()).decode('ascii')
-    headers = {'Authorization': f"Basic {auth}"}
-    VERSIONS = solcx.get_available_solc_versions(headers=headers)
+    VERSIONS = solcx.get_available_solc_versions()
 
 
 # auto-parametrize the all_versions fixture with all target solc versions