Hey, Harness Community!
Introduction
We are constantly adding new Entities to our GraphQL, and this makes the programmatic interaction with Harness something pretty interesting.
Naturally, we are starting to see multiple use cases that interact with Harness GraphQL programmatically, to get answers to questions like:
“How many instances do I have, for each Service? Ok, what about each Service by Environment?”
I’m addicted to Shell Script. It’s simple and powerful. But, depending on the complexity and how you manipulate your GraphQL resultset, it can become a nightmare to read the code (and support it).
So, I spent some time finding a way to comprehend the HTTP aspect of this interaction automatically, at the same time that I could easily manipulate dictionary/JSON collections.
Of course, the answer was Python.
I’ll explore this finding with you, while I introduce the very nice GQL Module.
I’ll not enforce pep-8, exception handling, etc. This blog post is just to give you a good introduction to this approach.
Requirements
I’ll explore this in the Tutorial. But, in case you want to test my project directly, we’ll need some Environment Variables set at the runtime.
You can follow this README.md for reference! 
Tutorial
What are the required imports?
For this example, I’ve imported these:
import os
import csv
import logging
from gql import Client, gql
from gql.transport.requests import RequestsHTTPTransport
And you can solve all dependencies by running:
python3 -m pip install -r https://raw.githubusercontent.com/gabrielcerioni/harness_instanceStats_gql_to_csv/main/requirements.txt
Second Step
Let’s define a simple logger and some “constant” that I’ll get from Environment Variables:
logging.basicConfig(format='%(asctime)s - %(levelname)s - %(message)s', level=logging.INFO)
API_KEY = os.environ.get('HARNESS_GRAPHQL_API_KEY')
API_ENDPOINT = os.environ.get('HARNESS_GRAPHQL_ENDPOINT')
OUTPUT_CSV_NAME_CONST = os.environ.get('HARNESS_GQL_CSV_NAME')
Third Step
I don’t want to make this code huge, so I’ll cut to the chase.
So, let’s define a good generic query function to deal with Harness GraphQL:
def generic_graphql_query(query):
req_headers = {
'x-api-key': API_KEY
}
_transport = RequestsHTTPTransport(
url=API_ENDPOINT,
headers=req_headers,
use_json=True,
)
# Create a GraphQL client using the defined transport
client = Client(transport=_transport, fetch_schema_from_transport=True)
# Provide a GraphQL query
generic_query = gql(query)
# Execute the query on the transport
result = client.execute(generic_query)
return result
And also, we can do something very similar to run mutations:
def generic_graphql_mutation(mutation_query, params):
req_headers = {
'x-api-key': API_KEY
}
_transport = RequestsHTTPTransport(
url=API_ENDPOINT,
headers=req_headers,
use_json=True,
)
# Create a GraphQL client using the defined transport
client = Client(transport=_transport, fetch_schema_from_transport=True)
# Provide a GraphQL query
generic_query = gql(mutation_query)
# Execute the query on the transport
result = client.execute(generic_query, variable_values=params)
return result
Real Use Cases
Let’s explore two real use cases from our Customers.
Use Case 1
Customer Statement: I need to generate (on-demand) a CSV Report for all Instances Deployed, by Service and Environment. And I also need the Service ID, to make sure I’m counting this right.
Resulting Project (I’m still enhancing this): GitHub - gabrielcerioni/harness_instanceStats_gql_to_csv: This is a simple Python that will parse instanceStats GraphQL Query into a CSV
With everything we did until this point, I also need two functions:
- One to retrieve a very simple
instanceStatsresult set; - Another one to get that and put everything on a UTF-8 CSV.
So, this is pretty much it:
def get_all_instances_by_service_by_env():
query = '''{
instanceStats(groupBy: [{entityAggregation: Service}, {entityAggregation: Environment}]) {
... on StackedData {
dataPoints {
key {
name
id
}
values {
key {
name
}
value
}
}
}
}
}'''
generic_query_result = generic_graphql_query(query)
return(generic_query_result)
def parse_result_to_csv(instanceStats_gql_resultset):
# just for readability - I'll build a cleaner result set to make it easier to CSV this later
clean_dict_list = []
result_list = instanceStats_gql_resultset['instanceStats']['dataPoints']
for service_item in result_list:
instances = []
service_name = service_item['key']['name']
service_id = service_item['key']['id']
instance_environments = service_item['values']
for service_instance in instance_environments:
current_dict_entry = {'Service_Name' : service_name, 'Service_ID': service_id, 'Environment' : service_instance['key']['name'], 'Instance_Count' : service_instance['value']}
clean_dict_list.append(current_dict_entry)
with open(OUTPUT_CSV_NAME_CONST, 'w', encoding='utf8', newline='') as output_file:
fc = csv.DictWriter(output_file, fieldnames=clean_dict_list[0].keys(),)
fc.writeheader()
fc.writerows(clean_dict_list)
return(clean_dict_list)
And then we can easily coordinate everything in the “main” entry point:
if __name__ == '__main__':
logging.info("Starting the Program...")
logging.info("Retrieving your current instanceStats GraphQL Query result set...")
result_from_query = get_all_instances_by_service_by_env()
logging.info("Done!")
logging.info("Expanding all rows from the nested dict - and then putting it on the CSV: {0}".format(OUTPUT_CSV_NAME_CONST))
parsed_result_set = parse_result_to_csv(result_from_query)
logging.info("Done! Outputting the list content here:")
print(parsed_result_set)
logging.info("Program Exited! Have a nice day!")
Use Case 2
Customer Statement: I need to generate an output with ALL Users from my account! But I have a lot, and this will paginate ad infinitum! Please help and KT this ASAP!
Resulting Project (I’m still enhancing this): GitHub - gabrielcerioni/harness_graphql_labs: Gabs the CSE - Harness - GraphQL Labs - Python
Well, my GH Project has a dummy loader, but I don’t recommend running that, ok?
We can focus on a function that will query all the users, but that knows how to deal with GraphQL Offset/pagination:
def get_harness_account_users():
offset = 0
has_more = True
total_user_list = []
while has_more:
query = '''{
users(limit: 100, offset: ''' + str(offset) + ''') {
pageInfo {
total
limit
hasMore
offset
}
nodes {
name
}
}
}'''
generic_query_result = generic_graphql_query(query)
loop_user_list = generic_query_result["users"]["nodes"]
total_user_list.extend(loop_user_list)
#total = generic_query_result["users"]["pageInfo"]["total"]
has_more = bool(generic_query_result["users"]["pageInfo"]["hasMore"])
if has_more:
offset = offset + 100
return total_user_list
So then we could have this very simple entry point:
if __name__ == '__main__':
logging.info("Starting the Program...")
logging.info("Getting all users from your Harness Account")
result_from_query = get_harness_account_users()
logging.info("Done! You have {0} users in your Account!".format(len(result_from_query)))
print("")
logging.info("Printing the User List on your STDOUT")
print(result_from_query)
logging.info("Program Exited!")
Outcome:
Just a quick example for Use Case 1:
Further reading:
Tags:
<cloud: aws, azure, tanzu, gcp, on-prem, kubernetes, github, python, graphql, gitops>
<function: ci,cd>
<role: swdev,devops,secops,itexec,sre>
<type: howto, experts>
<category: python, graphql>