Skip to main content

Async crawler and parsing service for data.gouv.fr

Project description

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.

Since it's called hydra, it also has mythical powers embedded:

  • analyse remote resource metadata over time to detect changes in the smartest way possible
  • if the remote resource is a CSV, convert it to a PostgreSQL table, ready for APIfication
  • send crawl and analysis info to a udata instance

CLI

Create database structure

Install udata-hydra dependencies and cli. poetry install

poetry run udata-hydra migrate

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 retry until the backoff is lifted.

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

Worker

A job queuing system is used to process long-running tasks. Launch the worker with the following command:

poetry run rq worker -c udata_hydra.worker

Monitor worker status:

poetry run rq info -c udata_hydra.worker --interval 1

CSV conversion to database

Converted CSV tables will be stored in the database specified via config.DATABASE_URL_CSV. For tests it's same database as for the catalog. Locally, docker compose will launch two distinct database containers.

API

Run

poetry install
poetry run 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 crawling status

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

Get worker status

$ curl -s "http://localhost:8000/api/status/worker/" | json_pp
{
   "queued" : {
      "default" : 0,
      "high" : 825,
      "low" : 655
   }
}

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 Webhook integration

** Set the config values**

Create a config.toml where your service and commands are launched, or specify a path to a TOML file via the HYDRA_SETTINGS environment variable. config.toml or equivalent will override values from udata_hydra/config_default.toml, lookup there for values that can/need to be defined.

UDATA_URI = "https://dev.local:7000/api/2"
UDATA_URI_API_KEY = "example.api.key"
SENTRY_DSN = "https://{my-sentry-dsn}"

The webhook integration sends HTTP messages to udata when resources are analyzed or checked to fill resources extras.

Regarding analysis, there is a phase called "change detection". It will try to guess if a resource has been modified based on different criterions:

  • harvest modified date in catalog
  • content-length and last-modified headers
  • checksum comparison over time

The payload should look something like:

{
   "analysis:content-length": 91661,
   "analysis:mime-type": "application/zip",
   "analysis:checksum": "bef1de04601dedaf2d127418759b16915ba083be",
   "analysis:last-modified-at": "2022-11-27T23:00:54.762000",
   "analysis:last-modified-detection": "harvest-resource-metadata",
}

Development

docker-compose

Multiple docker-compose files are provided:

  • a minimal docker-compose.yml with two PostgreSQL containers (one for catalog and metadata, the other for converted CSV to database)
  • docker-compose.broker.yml adds a Redis broker
  • docker-compose.test.yml launches a test DB, needed to run tests

NB: you can launch compose from multiple files like this: docker-compose -f docker-compose.yml -f docker-compose.test.yml up

Logging & Debugging

The log level can be adjusted using the environment variable LOG_LEVEL. For example, to set the log level to DEBUG when initializing the database, use LOG_LEVEL="DEBUG" udata-hydra init_db .

Writing a migration

  1. Add a file named migrations/{YYYYMMDD}_{description}.sql and write the SQL you need to perform migration.
  2. udata-hydra migrate will migrate the database as needeed.

Deployment

3 services need to be deployed for the full stack to run:

  • worker
  • api / app
  • crawler

Refer to each section to learn how to launch them. The only differences from dev to prod are:

  • use HYDRA_SETTINGS env var to point to your custom config.toml
  • use HYDRA_APP_SOCKET_PATH to configure where aiohttp should listen to a reverse proxy connection (eg nginx) and use udata-hydra-app to launch the app server

Project details


Release history Release notifications | RSS feed

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

udata_hydra-2.0.0.dev1224.tar.gz (31.5 kB view details)

Uploaded Source

Built Distribution

udata_hydra-2.0.0.dev1224-py3-none-any.whl (37.9 kB view details)

Uploaded Python 3

File details

Details for the file udata_hydra-2.0.0.dev1224.tar.gz.

File metadata

  • Download URL: udata_hydra-2.0.0.dev1224.tar.gz
  • Upload date:
  • Size: 31.5 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? No
  • Uploaded via: poetry/1.2.2 CPython/3.9.15 Linux/5.15.0-1030-aws

File hashes

Hashes for udata_hydra-2.0.0.dev1224.tar.gz
Algorithm Hash digest
SHA256 b2837f9ef22bfa730e4a57071faceadf1781621acb0c22c0993833ff0ce9c4fa
MD5 5abab0d8ff4e81d3283c5fa4371163ab
BLAKE2b-256 ec239255c1e736ec64c794901d0c90589e40b7a845e8313b6b4f706acbac8378

See more details on using hashes here.

File details

Details for the file udata_hydra-2.0.0.dev1224-py3-none-any.whl.

File metadata

File hashes

Hashes for udata_hydra-2.0.0.dev1224-py3-none-any.whl
Algorithm Hash digest
SHA256 caa0d3daa9e54cfc6e1f9dfd8426900bfd872559885a7837edd48bd227687856
MD5 838638688800995366d5a1a0c6595722
BLAKE2b-256 534ac9100a7a843b45e7c357c853b119afe30c8da0e8fc20852161199bd87f87

See more details on using hashes here.

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page