udata-hydra 0.1.0.dev64

Async crawler and datalake service for data.gouv.fr

udata-hydra 🦀

udata-hydra is an async metadata crawler for data.gouv.fr.

URLs are crawled via aiohttp, catalog and crawled metadata are stored in a PostgreSQL database.

CLI

Create database structure

Install udata-hydra dependencies and cli. make deps

udata-hydra init-db

Load (UPSERT) latest catalog version from data.gouv.fr

udata-hydra load-catalog

Crawler

udata-hydra-crawl

It will crawl (forever) the catalog according to config set in config.py.

BATCH_SIZE URLs are queued at each loop run.

The crawler will start with URLs never checked and then proceed with URLs crawled before SINCE interval. It will then wait until something changes (catalog or time).

There's a by-domain backoff mecanism. The crawler will wait when, for a given domain in a given batch, BACKOFF_NB_REQ is exceeded in a period of BACKOFF_PERIOD seconds. It will sleep and retry until the backoff is lifted.

If an URL matches one of the EXCLUDED_PATTERNS, it will never be checked.

A curses interface is available via:

HYDRA_CURSES_ENABLED=True udata-hydra-crawl

API

Run

pip install -r requirements.txt
adev runserver udata-hydra/app.py

Get latest check

Works with ?url={url} and ?resource_id={resource_id}.

$ curl -s "http://localhost:8000/api/checks/latest/?url=http://opendata-sig.saintdenis.re/datasets/661e19974bcc48849bbff7c9637c5c28_1.csv" | json_pp
{
   "status" : 200,
   "catalog_id" : 64148,
   "deleted" : false,
   "error" : null,
   "created_at" : "2021-02-06T12:19:08.203055",
   "response_time" : 0.830198049545288,
   "url" : "http://opendata-sig.saintdenis.re/datasets/661e19974bcc48849bbff7c9637c5c28_1.csv",
   "domain" : "opendata-sig.saintdenis.re",
   "timeout" : false,
   "id" : 114750,
   "dataset_id" : "5c34944606e3e73d4a551889",
   "resource_id" : "b3678c59-5b35-43ad-9379-fce29e5b56fe",
   "headers" : {
      "content-disposition" : "attachment; filename=\"xn--Dlimitation_des_cantons-bcc.csv\"",
      "server" : "openresty",
      "x-amz-meta-cachetime" : "191",
      "last-modified" : "Wed, 29 Apr 2020 02:19:04 GMT",
      "content-encoding" : "gzip",
      "content-type" : "text/csv",
      "cache-control" : "must-revalidate",
      "etag" : "\"20415964703d9ccc4815d7126aa3a6d8\"",
      "content-length" : "207",
      "date" : "Sat, 06 Feb 2021 12:19:08 GMT",
      "x-amz-meta-contentlastmodified" : "2018-11-19T09:38:28.490Z",
      "connection" : "keep-alive",
      "vary" : "Accept-Encoding"
   }
}

Get all checks for an URL or resource

Works with ?url={url} and ?resource_id={resource_id}.

$ curl -s "http://localhost:8000/api/checks/all/?url=http://www.drees.sante.gouv.fr/IMG/xls/er864.xls" | json_pp
[
   {
      "domain" : "www.drees.sante.gouv.fr",
      "dataset_id" : "53d6eadba3a72954d9dd62f5",
      "timeout" : false,
      "deleted" : false,
      "response_time" : null,
      "error" : "Cannot connect to host www.drees.sante.gouv.fr:443 ssl:True [SSLCertVerificationError: (1, \"[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: Hostname mismatch, certificate is not valid for 'www.drees.sante.gouv.fr'. (_ssl.c:1122)\")]",
      "catalog_id" : 232112,
      "url" : "http://www.drees.sante.gouv.fr/IMG/xls/er864.xls",
      "headers" : {},
      "id" : 165107,
      "created_at" : "2021-02-06T14:32:47.675854",
      "resource_id" : "93dfd449-9d26-4bb0-a6a9-ee49b1b8a4d7",
      "status" : null
   },
   {
      "timeout" : false,
      "deleted" : false,
      "response_time" : null,
      "error" : "Cannot connect to host www.drees.sante.gouv.fr:443 ssl:True [SSLCertVerificationError: (1, \"[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: Hostname mismatch, certificate is not valid for 'www.drees.sante.gouv.fr'. (_ssl.c:1122)\")]",
      "domain" : "www.drees.sante.gouv.fr",
      "dataset_id" : "53d6eadba3a72954d9dd62f5",
      "created_at" : "2020-12-24T17:06:58.158125",
      "resource_id" : "93dfd449-9d26-4bb0-a6a9-ee49b1b8a4d7",
      "status" : null,
      "catalog_id" : 232112,
      "url" : "http://www.drees.sante.gouv.fr/IMG/xls/er864.xls",
      "headers" : {},
      "id" : 65092
   }
]

Get modification date on resources

This tries to find a modification date for a given resource, by order of priority:

1. last-modified header if any
2. content-length comparison over multiple checks if any (precision depends on crawling frequency)

Works with ?url={url} and ?resource_id={resource_id}.

$ curl -s "http://localhost:8000/api/changed/?resource_id=f2d3e1ad-4d7d-46fc-91f8-c26f02c1e487" | json_pp
{
   "changed_at" : "2014-09-15T14:51:52",
   "detection" : "last-modified"
}

$ curl -s "http://localhost:8000/api/changed/?resource_id=f2d3e1ad-4d7d-46fc-91f8-c26f02c1e487" | json_pp
{
   "changed_at" : "2020-09-15T14:51:52",
   "detection" : "content-length"
}

Get crawling status

$ curl -s "http://localhost:8000/api/status/" | json_pp
{
   "fresh_checks_percentage" : 0.4,
   "pending_checks" : 142153,
   "total" : 142687,
   "fresh_checks" : 534,
   "checks_percentage" : 0.4
}

Get crawling stats

$ curl -s "http://localhost:8000/api/stats/" | json_pp
{
   "status" : [
      {
         "count" : 525,
         "percentage" : 98.3,
         "label" : "ok"
      },
      {
         "label" : "error",
         "percentage" : 1.3,
         "count" : 7
      },
      {
         "label" : "timeout",
         "percentage" : 0.4,
         "count" : 2
      }
   ],
   "status_codes" : [
      {
         "code" : 200,
         "count" : 413,
         "percentage" : 78.7
      },
      {
         "code" : 501,
         "percentage" : 12.4,
         "count" : 65
      },
      {
         "percentage" : 6.1,
         "count" : 32,
         "code" : 404
      },
      {
         "code" : 500,
         "percentage" : 2.7,
         "count" : 14
      },
      {
         "code" : 502,
         "count" : 1,
         "percentage" : 0.2
      }
   ]
}

Using Kafka integration

** Set the environment variables ** Rename the .env.sample to .env and fill it with the right values.

REDIS_URL = redis://localhost:6380/0
REDIS_HOST = localhost
REDIS_PORT = 6380
KAFKA_HOST = localhost
KAFKA_PORT = 9092
KAFKA_API_VERSION = 2.5.0
MINIO_URL = https://object.local.dev/
MINIO_USER = sample_user
MINIO_BUCKET = benchmark-de
MINIO_PWD = sample_pwd
MINIO_FOLDER = data
MAX_FILESIZE_ALLOWED = 1e9
UDATA_INSTANCE_NAME = udata

The kafka_integration module retrieves messages with the topics resource.created, resource.modified and resource.deleted sent by udata. The Kafka instance URI, Hydra API URL and Data Gouv API URL to be used can be defined in udata-hydra/config or overwritten with env variables. It can be launched using the CLI: udata-hydra run_kafka_integration. This will mark the corresponding resources as highest priority for the next crawling batch.

TODO

• non curse interface :sad:
• tests
• expose summary/status as API
• change detection API on url / resource
• handle GET request when 501 on HEAD
• handle GET requests for some domains
• denormalize interesting headers (length, mimetype, last-modified...)
• some sort of dashboard (dash?), or just plug postgrest and handle that elsewhere
• custom config file for pandas_profiling
• move API endpoints to /api endpoints