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# Copyright 2018 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import datetime
import logging
import os
from flask import Flask, render_template, request, Response
import sqlalchemy
app = Flask(__name__)
logger = logging.getLogger()
def init_connection_engine():
db_config = {
# [START cloud_sql_postgres_sqlalchemy_limit]
# Pool size is the maximum number of permanent connections to keep.
"pool_size": 5,
# Temporarily exceeds the set pool_size if no connections are available.
"max_overflow": 2,
# The total number of concurrent connections for your application will be
# a total of pool_size and max_overflow.
# [END cloud_sql_postgres_sqlalchemy_limit]
# [START cloud_sql_postgres_sqlalchemy_backoff]
# SQLAlchemy automatically uses delays between failed connection attempts,
# but provides no arguments for configuration.
# [END cloud_sql_postgres_sqlalchemy_backoff]
# [START cloud_sql_postgres_sqlalchemy_timeout]
# 'pool_timeout' is the maximum number of seconds to wait when retrieving a
# new connection from the pool. After the specified amount of time, an
# exception will be thrown.
"pool_timeout": 30, # 30 seconds
# [END cloud_sql_postgres_sqlalchemy_timeout]
# [START cloud_sql_postgres_sqlalchemy_lifetime]
# 'pool_recycle' is the maximum number of seconds a connection can persist.
# Connections that live longer than the specified amount of time will be
# reestablished
"pool_recycle": 1800, # 30 minutes
# [END cloud_sql_postgres_sqlalchemy_lifetime]
}
if os.environ.get("DB_HOST"):
return init_tcp_connection_engine(db_config)
else:
return init_unix_connection_engine(db_config)
def init_tcp_connection_engine(db_config):
# [START cloud_sql_postgres_sqlalchemy_create_tcp]
# Remember - storing secrets in plaintext is potentially unsafe. Consider using
# something like https://cloud.google.com/secret-manager/docs/overview to help keep
# secrets secret.
db_user = os.environ["DB_USER"]
db_pass = os.environ["DB_PASS"]
db_name = os.environ["DB_NAME"]
db_host = os.environ["DB_HOST"]
# Extract host and port from db_host
host_args = db_host.split(":")
db_hostname, db_port = host_args[0], int(host_args[1])
pool = sqlalchemy.create_engine(
# Equivalent URL:
# postgres+pg8000://<db_user>:<db_pass>@<db_host>:<db_port>/<db_name>
sqlalchemy.engine.url.URL(
drivername="postgresql+pg8000",
username=db_user, # e.g. "my-database-user"
password=db_pass, # e.g. "my-database-password"
host=db_hostname, # e.g. "127.0.0.1"
port=db_port, # e.g. 5432
database=db_name # e.g. "my-database-name"
),
**db_config
)
# [END cloud_sql_postgres_sqlalchemy_create_tcp]
pool.dialect.description_encoding = None
return pool
def init_unix_connection_engine(db_config):
# [START cloud_sql_postgres_sqlalchemy_create_socket]
# Remember - storing secrets in plaintext is potentially unsafe. Consider using
# something like https://cloud.google.com/secret-manager/docs/overview to help keep
# secrets secret.
db_user = os.environ["DB_USER"]
db_pass = os.environ["DB_PASS"]
db_name = os.environ["DB_NAME"]
db_socket_dir = os.environ.get("DB_SOCKET_DIR", "/cloudsql")
cloud_sql_connection_name = os.environ["CLOUD_SQL_CONNECTION_NAME"]
pool = sqlalchemy.create_engine(
# Equivalent URL:
# postgres+pg8000://<db_user>:<db_pass>@/<db_name>
# ?unix_sock=<socket_path>/<cloud_sql_instance_name>/.s.PGSQL.5432
sqlalchemy.engine.url.URL(
drivername="postgresql+pg8000",
username=db_user, # e.g. "my-database-user"
password=db_pass, # e.g. "my-database-password"
database=db_name, # e.g. "my-database-name"
query={
"unix_sock": "{}/{}/.s.PGSQL.5432".format(
db_socket_dir, # e.g. "/cloudsql"
cloud_sql_connection_name) # i.e "<PROJECT-NAME>:<INSTANCE-REGION>:<INSTANCE-NAME>"
}
),
**db_config
)
# [END cloud_sql_postgres_sqlalchemy_create_socket]
pool.dialect.description_encoding = None
return pool
# This global variable is declared with a value of `None`, instead of calling
# `init_connection_engine()` immediately, to simplify testing. In general, it
# is safe to initialize your database connection pool when your script starts
# -- there is no need to wait for the first request.
db = None
@app.before_first_request
def create_tables():
global db
db = init_connection_engine()
# Create tables (if they don't already exist)
with db.connect() as conn:
conn.execute(
"CREATE TABLE IF NOT EXISTS votes "
"( vote_id SERIAL NOT NULL, time_cast timestamp NOT NULL, "
"candidate VARCHAR(6) NOT NULL, PRIMARY KEY (vote_id) );"
)
@app.route('/', methods=['GET'])
def index():
context = get_index_context()
return render_template('index.html', **context)
def get_index_context():
votes = []
with db.connect() as conn:
# Execute the query and fetch all results
recent_votes = conn.execute(
"SELECT candidate, time_cast FROM votes "
"ORDER BY time_cast DESC LIMIT 5"
).fetchall()
# Convert the results into a list of dicts representing votes
for row in recent_votes:
votes.append({
'candidate': row[0],
'time_cast': row[1]
})
stmt = sqlalchemy.text(
"SELECT COUNT(vote_id) FROM votes WHERE candidate=:candidate")
# Count number of votes for tabs
tab_result = conn.execute(stmt, candidate="TABS").fetchone()
tab_count = tab_result[0]
# Count number of votes for spaces
space_result = conn.execute(stmt, candidate="SPACES").fetchone()
space_count = space_result[0]
return {
'space_count': space_count,
'recent_votes': votes,
'tab_count': tab_count,
}
@app.route('/', methods=['POST'])
def save_vote():
# Get the team and time the vote was cast.
team = request.form['team']
time_cast = datetime.datetime.utcnow()
# Verify that the team is one of the allowed options
if team != "TABS" and team != "SPACES":
logger.warning(team)
return Response(
response="Invalid team specified.",
status=400
)
# [START cloud_sql_postgres_sqlalchemy_connection]
# Preparing a statement before hand can help protect against injections.
stmt = sqlalchemy.text(
"INSERT INTO votes (time_cast, candidate)"
" VALUES (:time_cast, :candidate)"
)
try:
# Using a with statement ensures that the connection is always released
# back into the pool at the end of statement (even if an error occurs)
with db.connect() as conn:
conn.execute(stmt, time_cast=time_cast, candidate=team)
except Exception as e:
# If something goes wrong, handle the error in this section. This might
# involve retrying or adjusting parameters depending on the situation.
# [START_EXCLUDE]
logger.exception(e)
return Response(
status=500,
response="Unable to successfully cast vote! Please check the "
"application logs for more details."
)
# [END_EXCLUDE]
# [END cloud_sql_postgres_sqlalchemy_connection]
return Response(
status=200,
response="Vote successfully cast for '{}' at time {}!".format(
team, time_cast)
)
if __name__ == '__main__':
app.run(host='127.0.0.1', port=8080, debug=True)
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