Refactor promql_api after project structure change

Refactored prompql_api after project structure change.
Fix review comments and make a better read me.

Change-Id: I40b7b2da40d85e9f297d4bb87d8633c71bdd1ec0
Issue-ID: ONAPARC-452
Signed-off-by: Rajamohan Raj <rajamohan.raj@intel.com>

3 files changed, 147 insertions, 0 deletions

diff --git a/vnfs/DAaaS/lib/promql_api/README.md b/vnfs/DAaaS/lib/promql_api/README.md
new file mode 100644
index 00000000..de64fe0b
--- /dev/null
+++ b/vnfs/DAaaS/lib/promql_api/README.md
@@ -0,0 +1,65 @@
+## What does this API do ?
+This api as of now provides a function which takes in a lits of 'LABELS' of prometheus
+and returns the corresponding result_sets in a list.
+
+For eg:
+If the labels is
+
+```
+LABELS = ['irate(collectd_cpufreq{exported_instance="otconap7",cpufreq="1"}[2m])']
+```
+
+The return is:
+
+```
+[{'metric': {'cpufreq': '1',
+             'endpoint': 'collectd-prometheus',
+             'exported_instance': 'otconap7',
+             'instance': '172.25.103.1:9103',
+             'job': 'collectd',
+             'namespace': 'edge1',
+             'pod': 'plundering-liger-collectd-wz7xg',
+             'service': 'collectd'},
+  'value': [1559177169.415, '119727200']}]
+```
+
+## How to use this API ?
+
+```
+1. Copy the directory 'promql_api' to your working directory. 
+```
+
+```
+2. Import the API function: query
+from promql_api.prom_ql_api import query
+```
+
+```
+3. have a global or local variable as 'LABELS'
+LABELS = ['irate(collectd_cpufreq{exported_instance="otconap7",cpufreq="1"}[2m])']
+```
+
+```
+4. Store the result set in a list:
+list_of_result_sets = query(LABELS)
+```
+
+## Troubleshooting tips
+
+* Check the sample file - sample_promql_query.py in the repo ( sample-apps/m3db_promql)
+* Make sure the file "__init__.py" is present in promql_api directory after you copy the directory.
+* Make sure environment variables like "DATA_ENDPOINT" are correctly set.
+* Logs are generated in the directory where the query function is called.
+* sample log file - promql_api.log
+
+```
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: set_log_config :: INFO :: Set the log configs.
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: load_and_validate_env_vars :: INFO :: Loading the env variables ...
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: load_and_validate_env_vars :: ERROR :: Env var: DATA_ENDPOINT not         found !
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: query :: INFO :: Forming the get request ...
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: query :: INFO :: API request::: URL: http://172.25.103.1:30090/api/v1/    query
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: query :: INFO :: API request::: params: {'query':                         'irate(collectd_cpufreq{exported_instance="otconap7",cpufreq="1"}[2m])'}
+ 05-30-2019 08:47:53PM ::connectionpool.py :: _new_conn :: DEBUG :: Starting new HTTP connection (1): 172.25.103.1   05-30-2019 08:47:53PM ::connectionpool.py :: _make_request :: DEBUG :: http://172.25.103.1:30090 "GET /api/v1/      query?query=irate%28collectd_cpufreq%7Bexported_instance%3D%22otconap7%22%2Ccpufreq%3D%221%22%7D%5B2m%5D%29 HTTP/1. 1" 200 370
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: query :: INFO :: ::::::::::RESULTS:::::::::::::                           irate(collectd_cpufreq{exported_instance="otconap7",cpufreq="1"}[2m])
+ 05-30-2019 08:47:53PM ::prom_ql_api.py :: query :: INFO :: {'metric': {'cpufreq': '1', 'endpoint': 'collectd-       prometheus', 'exported_instance': 'otconap7', 'instance': '172.25.103.1:9103', 'job': 'collectd', 'namespace':      'edge1', 'pod': 'plundering-liger-collectd-wz7xg', 'service': 'collectd'}, 'value': [1559249299.084, '236300']}
+ ```
diff --git a/vnfs/DAaaS/lib/promql_api/__init__.py b/vnfs/DAaaS/lib/promql_api/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/vnfs/DAaaS/lib/promql_api/__init__.py
diff --git a/vnfs/DAaaS/lib/promql_api/prom_ql_api.py b/vnfs/DAaaS/lib/promql_api/prom_ql_api.py
new file mode 100644
index 00000000..970d2416
--- /dev/null
+++ b/vnfs/DAaaS/lib/promql_api/prom_ql_api.py
@@ -0,0 +1,82 @@
+from __future__ import print_function
+from os import environ
+import logging
+import requests
+from requests.exceptions import HTTPError
+
+
+
+API_VERSION = '/api/v1/query'
+LIST_OF_ENV_VARIABLES = ["DATA_ENDPOINT"]
+MAP_ENV_VARIABLES = dict()
+LOG = logging.getLogger(__name__)
+
+def set_log_config():
+    logging.basicConfig(format='%(asctime)s ::%(filename)s :: %(funcName)s :: %(levelname)s :: %(message)s',
+                    datefmt='%m-%d-%Y %I:%M:%S%p',
+                    level=logging.DEBUG,
+                    filename='promql_api.log',
+                    filemode='w')
+    LOG.info("Set the log configs.")
+
+
+def load_and_validate_env_vars(list_of_env_vars):
+    LOG.info("Loading the env variables ...")
+    for env_var in list_of_env_vars:
+        if env_var in environ:
+            LOG.info("Found env variable: {} ".format(env_var.upper()))
+            MAP_ENV_VARIABLES[env_var.upper()] = environ.get(env_var)
+        else:
+            #MAP_ENV_VARIABLES['DATA_ENDPOINT']='http://127.0.0.1:30090' # to be deleted
+            LOG.error("Env var: {} not found ! ".format(env_var.upper()))
+            raise KeyError("Env variable: {} not found ! ".format(env_var.upper()))
+
+
+def query(LABELS):
+    """
+    Input parameters:
+        LABELS : a list of the LABELS like ['irate(collectd_cpufreq{exported_instance="otconap7",cpufreq="1"}[2m])']
+    Return:
+        returns a list of  result sets of different labels.
+        SAMPLE O/P:
+        [{'metric': {'cpufreq': '1',
+             'endpoint': 'collectd-prometheus',
+             'exported_instance': 'otconap7',
+             'instance': '172.25.103.1:9103',
+             'job': 'collectd',
+             'namespace': 'edge1',
+             'pod': 'plundering-liger-collectd-wz7xg',
+             'service': 'collectd'},
+        'value': [1559177169.415, '119727200']}]
+    """
+    set_log_config()
+    load_and_validate_env_vars(LIST_OF_ENV_VARIABLES)
+    LOG.info("Forming the get request ...")
+    list_of_substrings = []
+    params_map = {}
+    list_of_result_sets = []
+    list_of_substrings.append(MAP_ENV_VARIABLES['DATA_ENDPOINT'])
+    list_of_substrings.append(API_VERSION)
+    url = ''.join(list_of_substrings)
+
+    for each_label in LABELS:
+        params_map['query'] = each_label
+        try:
+            LOG.info('API request::: URL: {} '.format(url))
+            LOG.info('API request::: params: {} '.format(params_map))
+            response = requests.get(url, params=params_map)
+            response.raise_for_status()
+        except HTTPError as http_err:
+            print(f'HTTP error occurred: {http_err}')
+            return None
+        except Exception as err:
+            print(f'Other error occurred: {err}')
+            return None
+        else:
+
+            results = response.json()['data']['result']
+            LOG.info('::::::::::RESULTS::::::::::::: {}'.format(each_label))
+            for each_result in results:
+                LOG.info(each_result)
+            list_of_result_sets.append(results)
+    return list_of_result_sets