Prefer uppercase PROMETHEUS_MULTIPROC_DIR

Author: PeterJCLaw

Dockerfile

@@ -20,6 +20,6 @@ COPY alembic.ini alembic.ini
 
 EXPOSE 2017
 
-ENV prometheus_multiproc_dir /tmp/routemaster/prometheus
+ENV PROMETHEUS_MULTIPROC_DIR /tmp/routemaster/prometheus
 
 CMD ["routemaster", "--config-file=config.yaml", "serve"]

plugins/routemaster-prometheus/README.md

@@ -13,7 +13,7 @@ Usage, in your Routemaster configuration file:
 This package is based on the official Python Promeutheus bindings in
 [`prometheus_client`](https://pypi.org/project/prometheus_client/). In order
 for that package to operate in a multithreaded program such as Routemaster,
-the environment variable `prometheus_multiproc_dir` must be set to a writeable
+the environment variable `PROMETHEUS_MULTIPROC_DIR` must be set to a writeable
 directory for temporary files. It does not need to be backed up as nothing
 is persisted between application launches.
 

plugins/routemaster-prometheus/routemaster_prometheus/__init__.py

@@ -62,12 +62,17 @@ def __init__(
         path='/metrics',
     ):
         self.path = path
-        metrics_path = os.environ.get('prometheus_multiproc_dir')
+        # Lower case spelling prometheus_multiproc_dir is deprecated but still
+        # supported by prometheus_client.
+        metrics_path = (
+            os.environ.get('PROMETHEUS_MULTIPROC_DIR') or
+            os.environ.get('prometheus_multiproc_dir')
+        )
 
         if not metrics_path:
             raise ValueError(
                 "PrometheusLogger requires the environment variable "
-                "`prometheus_multiproc_dir` to be set to a writeable "
+                "`PROMETHEUS_MULTIPROC_DIR` to be set to a writeable "
                 "directory.",
             )
 

plugins/tests/test_logging_plugins.py

@@ -132,7 +132,7 @@ def root():
 
 
 def test_prometheus_logger_wipes_directory_on_startup(app):
-    tmp = pathlib.Path(os.environ['prometheus_multiproc_dir'])
+    tmp = pathlib.Path(os.environ['PROMETHEUS_MULTIPROC_DIR'])
     tmp.mkdir(parents=True, exist_ok=True)
 
     filepath = tmp / 'foo.txt'
@@ -181,10 +181,10 @@ def test_prometheus_logger_ignores_metrics_path(routemaster_serve_subprocess):
 
 
 def test_prometheus_logger_validates_metrics_path(app):
-    orig = os.environ['prometheus_multiproc_dir']
-    os.environ['prometheus_multiproc_dir'] = ''
+    orig = os.environ['PROMETHEUS_MULTIPROC_DIR']
+    os.environ['PROMETHEUS_MULTIPROC_DIR'] = ''
 
     with pytest.raises(ValueError):
         PrometheusLogger(app.config)
 
-    os.environ['prometheus_multiproc_dir'] = orig
+    os.environ['PROMETHEUS_MULTIPROC_DIR'] = orig

setup.cfg

@@ -46,4 +46,4 @@ extend_skip =
 [tool:pytest]
 python_paths=test_data/plugins/
 env =
-    prometheus_multiproc_dir=/tmp/routemaster-tests/prometheus
+    PROMETHEUS_MULTIPROC_DIR=/tmp/routemaster-tests/prometheus

tox.ini

@@ -16,7 +16,7 @@ passenv=
     PG_USER
     PG_PASS
 setenv =
-    prometheus_multiproc_dir={envtmpdir}
+    PROMETHEUS_MULTIPROC_DIR={envtmpdir}
 commands =
     mkdir -p build/results
     mkdir -p build/artifacts