From 1b63dd8c897e2444070b015e940d3f1b31fceefd Mon Sep 17 00:00:00 2001
From: Danni Moiseyev <danni@redislabs.com>
Date: Mon, 4 May 2020 11:03:29 +0300
Subject: [PATCH] Fix timezone issues, update Dockerfile

---
 Dockerfile                | 12 +++++++-----
 GrafanaDatastoreServer.py | 10 +++-------
 README.md                 |  3 +++
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index b627184..fdd929a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,11 +1,13 @@
-FROM python:alpine3.9
+FROM python:3-alpine
+
 
 WORKDIR /app/
 
 COPY requirements.txt /app/
-RUN apk add --no-cache --virtual build-deps gcc musl-dev libffi-dev \
-    && pip install -r requirements.txt \
-    && apk del build-deps
+
+RUN apk update && apk add --no-cache --virtual build-deps build-base gcc musl-dev libffi-dev libev-dev
+RUN pip install -r requirements.txt
+RUN apk del build-deps
 
 COPY GrafanaDatastoreServer.py /app/
 
@@ -13,4 +15,4 @@ EXPOSE 8080
 ENV REDIS_HOST=localhost
 ENV REDIS_PORT=6379
 
-CMD /app/GrafanaDatastoreServer.py --redis-server $REDIS_HOST --redis-port $REDIS_PORT
\ No newline at end of file
+CMD /app/GrafanaDatastoreServer.py --redis-server $REDIS_HOST --redis-port $REDIS_PORT
diff --git a/GrafanaDatastoreServer.py b/GrafanaDatastoreServer.py
index 2bb7361..acbfc16 100755
--- a/GrafanaDatastoreServer.py
+++ b/GrafanaDatastoreServer.py
@@ -12,8 +12,6 @@
 app = Flask(__name__)
 CORS(app)
 
-EPOCH = datetime(1970, 1, 1, 0, 0, 0)
-
 REDIS_POOL = None
 SCAN_TYPE_SCRIPT = """local cursor, pat, typ, cnt = ARGV[1], ARGV[2], ARGV[3], ARGV[4] or 100
 local rep = {}
@@ -63,11 +61,9 @@ def query():
     request = flask.request.get_json()
     response = []
 
-    # !!! dates 'from' and 'to' are expected to be in UTC, which is what Grafana provides here.
-    # If not in UTC, use pytz to set to UTC timezone and subtract the utcoffset().
-    # Time delta calculations should always be done in UTC to avoid pitfalls of daylight offset changes.
-    stime = (dateutil.parser.parse(request['range']['from']) - EPOCH) / timedelta(milliseconds=1)
-    etime = (dateutil.parser.parse(request['range']['to']) - EPOCH) / timedelta(milliseconds=1)
+    # dates 'from' and 'to' are expected to be in UTC, which is what Grafana provides here.
+    stime = dateutil.parser.parse(request['range']['from']).timestamp() * 1000
+    etime = dateutil.parser.parse(request['range']['to']).timestamp() * 1000
 
     redis_client = redis.Redis(connection_pool=REDIS_POOL)
     targets = process_targets([t['target'] for t in request['targets']], redis_client)
diff --git a/README.md b/README.md
index 94320ba..fbd7b43 100644
--- a/README.md
+++ b/README.md
@@ -51,3 +51,6 @@ optional arguments:
   --redis-port REDIS_PORT
                         redis server port
 ```
+
+#### Note about timezone
+Grafana uses UTC timestamps to query its datastores. This datastore will use the same timestamps to query Redis, which means that it assumes all timestamps are UTC based.
\ No newline at end of file