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# Copyright 2019 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 os
import subprocess
from flask import Flask, make_response, request
app = Flask(__name__)
# [START run_system_package_handler]
@app.route("/diagram.png", methods=["GET"])
def index():
# Takes an HTTP GET request with query param dot and
# returns a png with the rendered DOT diagram in a HTTP response.
try:
image = create_diagram(request.args.get("dot"))
response = make_response(image)
response.headers.set("Content-Type", "image/png")
return response
except Exception as e:
print("error: {}".format(e))
# If no graphviz definition or bad graphviz def, return 400
if "syntax" in str(e):
return "Bad Request: {}".format(e), 400
return "Internal Server Error", 500
# [END run_system_package_handler]
# [START run_system_package_exec]
def create_diagram(dot):
# Generates a diagram based on a graphviz DOT diagram description.
if not dot:
raise Exception("syntax: no graphviz definition provided")
dot_args = [ # These args add a watermark to the dot graphic.
"-Glabel=Made on Cloud Run",
"-Gfontsize=10",
"-Glabeljust=right",
"-Glabelloc=bottom",
"-Gfontcolor=gray",
"-Tpng",
]
# Uses local `dot` binary from Graphviz:
# https://graphviz.gitlab.io
image = subprocess.run(
["dot"] + dot_args, input=dot.encode("utf-8"), stdout=subprocess.PIPE
).stdout
if not image:
raise Exception("syntax: bad graphviz definition provided")
return image
# [END run_system_package_exec]
if __name__ == "__main__":
PORT = int(os.getenv("PORT")) if os.getenv("PORT") else 8080
# This is used when running locally. Gunicorn is used to run the
# application on Cloud Run. See entrypoint in Dockerfile.
app.run(host="127.0.0.1", port=PORT, debug=True)