healthchecks/hc/api/views.py

from datetime import timedelta as td
import uuid

from django.conf import settings
from django.core.exceptions import SuspiciousOperation
from django.db import connection
from django.http import (HttpResponse, HttpResponseForbidden,
                         HttpResponseNotFound, JsonResponse)
from django.shortcuts import get_object_or_404
from django.utils import timezone
from django.views.decorators.cache import never_cache
from django.views.decorators.csrf import csrf_exempt
from django.views.decorators.http import require_GET, require_POST

from hc.api import schemas
from hc.api.decorators import authorize, authorize_read, validate_json
from hc.api.models import Check, Notification, Channel
from hc.lib.badges import check_signature, get_badge_svg


@csrf_exempt
@never_cache
def ping(request, code, is_fail=False):
    check = get_object_or_404(Check, code=code)

    headers = request.META
    remote_addr = headers.get("HTTP_X_FORWARDED_FOR", headers["REMOTE_ADDR"])
    remote_addr = remote_addr.split(",")[0]
    scheme = headers.get("HTTP_X_FORWARDED_PROTO", "http")
    method = headers["REQUEST_METHOD"]
    ua = headers.get("HTTP_USER_AGENT", "")
    body = request.body.decode()

    check.ping(remote_addr, scheme, method, ua, body, is_fail)

    response = HttpResponse("OK")
    response["Access-Control-Allow-Origin"] = "*"
    return response


def _lookup(user, spec):
    unique_fields = spec.get("unique", [])
    if unique_fields:
        existing_checks = Check.objects.filter(user=user)
        if "name" in unique_fields:
            existing_checks = existing_checks.filter(name=spec.get("name"))
        if "tags" in unique_fields:
            existing_checks = existing_checks.filter(tags=spec.get("tags"))
        if "timeout" in unique_fields:
            timeout = td(seconds=spec["timeout"])
            existing_checks = existing_checks.filter(timeout=timeout)
        if "grace" in unique_fields:
            grace = td(seconds=spec["grace"])
            existing_checks = existing_checks.filter(grace=grace)

        return existing_checks.first()


def _update(check, spec):
    if "name" in spec:
        check.name = spec["name"]

    if "tags" in spec:
        check.tags = spec["tags"]

    if "timeout" in spec and "schedule" not in spec:
        check.kind = "simple"
        check.timeout = td(seconds=spec["timeout"])

    if "grace" in spec:
        check.grace = td(seconds=spec["grace"])

    if "schedule" in spec:
        check.kind = "cron"
        check.schedule = spec["schedule"]
        if "tz" in spec:
            check.tz = spec["tz"]

    check.save()

    # This needs to be done after saving the check, because of
    # the M2M relation between checks and channels:
    if "channels" in spec:
        if spec["channels"] == "*":
            check.assign_all_channels()
        elif spec["channels"] == "":
            check.channel_set.clear()
        else:
            channels = []
            for chunk in spec["channels"].split(","):
                try:
                    chunk = uuid.UUID(chunk)
                except ValueError:
                    raise SuspiciousOperation("Invalid channel identifier")

                try:
                    channel = Channel.objects.get(code=chunk)
                    channels.append(channel)
                except Channel.DoesNotExist:
                    raise SuspiciousOperation("Invalid channel identifier")
            check.channel_set.set(channels)

    return check


@validate_json()
@authorize_read
def get_checks(request):
    q = Check.objects.filter(user=request.user)

    tags = set(request.GET.getlist("tag"))
    for tag in tags:
        # approximate filtering by tags
        q = q.filter(tags__contains=tag)

    checks = []
    for check in q:
        # precise, final filtering
        if not tags or check.matches_tag_set(tags):
            checks.append(check.to_dict())

    return JsonResponse({"checks": checks})


@validate_json(schemas.check)
@authorize
def create_check(request):
    created = False
    check = _lookup(request.user, request.json)
    if check is None:
        num_checks = Check.objects.filter(user=request.user).count()
        if num_checks >= request.user.profile.check_limit:
            return HttpResponseForbidden()

        check = Check(user=request.user)
        created = True

    _update(check, request.json)
    return JsonResponse(check.to_dict(), status=201 if created else 200)


@csrf_exempt
def checks(request):
    if request.method == "GET":
        return get_checks(request)

    elif request.method == "POST":
        return create_check(request)

    return HttpResponse(status=405)


@require_GET
@validate_json()
@authorize_read
def channels(request):
    q = Channel.objects.filter(user=request.user)
    channels = [ch.to_dict() for ch in q]
    return JsonResponse({"channels": channels})


@csrf_exempt
@validate_json(schemas.check)
@authorize
def update(request, code):
    check = get_object_or_404(Check, code=code)
    if check.user != request.user:
        return HttpResponseForbidden()

    if request.method == "POST":
        _update(check, request.json)
        return JsonResponse(check.to_dict())

    elif request.method == "DELETE":
        response = check.to_dict()
        check.delete()
        return JsonResponse(response)

    # Otherwise, method not allowed
    return HttpResponse(status=405)


@csrf_exempt
@require_POST
@validate_json()
@authorize
def pause(request, code):
    check = get_object_or_404(Check, code=code)
    if check.user != request.user:
        return HttpResponseForbidden()

    check.status = "paused"
    check.save()
    return JsonResponse(check.to_dict())


@never_cache
def badge(request, username, signature, tag, format="svg"):
    if not check_signature(username, tag, signature):
        return HttpResponseNotFound()

    status = "up"
    q = Check.objects.filter(user__username=username)
    if tag != "*":
        q = q.filter(tags__contains=tag)
        label = tag
    else:
        label = settings.MASTER_BADGE_LABEL

    for check in q:
        if tag != "*" and tag not in check.tags_list():
            continue

        check_status = check.get_status()
        if status == "up" and check_status == "grace":
            status = "late"

        if check_status == "down":
            status = "down"
            break

    if format == "json":
        return JsonResponse({"status": status})

    svg = get_badge_svg(label, status)
    return HttpResponse(svg, content_type="image/svg+xml")


@csrf_exempt
def bounce(request, code):
    notification = get_object_or_404(Notification, code=code)

    # If webhook is more than 10 minutes late, don't accept it:
    td = timezone.now() - notification.created
    if td.total_seconds() > 600:
        return HttpResponseForbidden()

    notification.error = request.body.decode()[:200]
    notification.save()

    notification.channel.email_verified = False
    notification.channel.save()

    return HttpResponse()


def status(request):
    with connection.cursor() as c:
        c.execute("SELECT 1")
        c.fetchone()

    return HttpResponse("OK")