software/grafana: version up and include loki/promtail

This enable vieiwing applications logs directly in grafana, as long as
loki agent can access the log file and the regular expressions to parse
the logs are defined

Other changes:
 - provision data sources automatically so that user do not have to add
   them manually
 - update TODO in README
 - introduce a SR test
 - switch to dep to install dependencies, because that's how these
  packages manage their dependencies.

Versions up:
  grafana: v6.3.0
  telegraf: v1.11.1-0
  influxdb: v1.7.8rc1
New:
  loki: v0.3.0

software/grafana/README.md

 # grafana / telegraf / influxdb
 
+This is an experimental integration, mainly to evaluate these solutions.
 
 ## Custom telegraf plugins
 
@@ -7,24 +8,20 @@
 See https://github.com/influxdata/telegraf to learn about plugins.
 
 Useful plugins in this context are probably
-[exec](https://github.com/influxdata/telegraf/tree/1.5.1/plugins/inputs/exec)
+[exec](https://github.com/influxdata/telegraf/tree/1.11.1/plugins/inputs/exec),
+[logparser](https://github.com/influxdata/telegraf/tree/1.11.1/plugins/inputs/logparser)
 or
-[httpjson](https://github.com/influxdata/telegraf/tree/1.5.1/plugins/inputs/httpjson).
+[http](https://github.com/influxdata/telegraf/tree/1.11.1/plugins/inputs/http).
 
 Telegraf will save in the `telegraf` database from the embedded influxdb server.
 
 
 ## Grafana
 
-You'll have to add yourself the influxdb data source in grafana, using the
-parameters published by the slapos instance.
+A default user is created, username and password are published as connection
+parameters. You can add more users in grafana interface.
 
-http://docs.grafana.org/features/datasources/influxdb/
-
-When adding datasource, use *proxy* option, otherwise Grafana makes your
-browser query influxdb directly, which also uses a self signed certificate.
-One workaround is to configure your browser to also accept influxdb certificate
-before using grafana, but using proxy seems easier.
+Datasources should be automatically added.
 
 ## Influxdb
 
@@ -34,8 +31,32 @@ One important thing to notice is that the backup protocol is enabled on ipv4
 provided by slapos, so make sure this ip is not reachable from untrusted
 sources.
 
-## TODO
+# Ingesting/Visualizing logs
+
+Eventhough main feature is visualizing metrics, Grafana has a feature called "Explore" to view logs for a time frame.
+The following backend can be used:
+
+## Loki
+
+See `TestLoki` in test for an example.
+
+## Influxdb
+
+Influxdb logs only have tags and there does not seem to be a way to search (except than tag and time frame).
+
+To inject log files containing:
+```
+INFO the message
+WARN another message
+```
+
+use config like:
+
+```
+[[inputs.logparser]]
+  files = ["/tmp/x*.log", "/tmp/aaa.log"]
 
-* influxdb and telegraf runs with very low priority, this could become an option
-* make one partition for each service and use switch software type
-* make it easier to add custom configuration (how ?)
+  [inputs.logparser.grok]
+  measurement = "logs"
+  patterns = ['^%{WORD:level:tag} %{GREEDYDATA:message:string}']
+```

software/grafana/buildout.hash.cfg

@@ -15,7 +15,7 @@
 
 [instance-profile]
 filename = instance.cfg.in
-md5sum = 461d515da03de5e422e6f75189d09184
+md5sum = 8abfd8ce01c375257e94f64824478f5c
 
 [influxdb-config-file]
 filename = influxdb-config-file.cfg.in
@@ -28,3 +28,15 @@ md5sum = a1a9c22c2a7829c66a49fc2504604d21
 [grafana-config-file]
 filename = grafana-config-file.cfg.in
 md5sum = 8244d430905b968795c7946049bed9e3
+
+[grafana-provisioning-config-file]
+filename = grafana-provisioning-config-file.cfg.in
+md5sum = 3aa0f1ed752b2a59ea2b5e7c1733daf3
+
+[loki-config-file]
+filename = loki-config-file.cfg.in
+md5sum = 02ba5acf23fcf88f5594919f46838533
+
+[promtail-config-file]
+filename = promtail-config-file.cfg.in
+md5sum = c77788d0a3cc654ad9393eb4b1f31e94

software/grafana/grafana-provisioning-config-file.cfg.in

+# https://grafana.com/docs/administration/provisioning/#example-datasource-config-file
+
+apiVersion: 1
+
+datasources:
+- name: telegraf
+  type: influxdb
+  access: proxy
+  url: {{ influxdb['url'] }}
+  user: {{ influxdb['auth-username'] }}
+  database: telegraf
+  isDefault: true
+  jsonData:
+    tlsSkipVerify: true
+  secureJsonData:
+    password: {{ influxdb['auth-password'] }}
+  version: 1
+  editable: false
+- name: loki
+  type: loki
+  access: proxy
+  url: {{ loki['url'] }}
+  version: 1
+  editable: false

software/grafana/instance-input-schema.json

@@ -28,6 +28,11 @@
       "description": "Name used in From: header of emails",
       "default": "Grafana",
       "type": "string"
+    },
+    "promtail-extra-scrape-config": {
+      "description": "Raw promtail config (experimental parameter, see https://github.com/grafana/loki/blob/master/docs/promtail.md#scrape-configs for detail)",
+      "default": "",
+      "type": "string"
     }
   }
 }

software/grafana/instance.cfg.in

@@ -41,11 +41,14 @@ grafana-data-dir = ${:grafana-dir}/data
 grafana-logs-dir = ${:var}/log
 grafana-plugins-dir = ${:grafana-dir}/plugins
 grafana-provisioning-config-dir = ${:grafana-dir}/provisioning-config
-grafana-provisioning-datasources = ${:grafana-provisioning-config-dir}/datasources
-grafana-provisioning-dashboards = ${:grafana-provisioning-config-dir}/dashboards
+grafana-provisioning-datasources-dir = ${:grafana-provisioning-config-dir}/datasources
+grafana-provisioning-dashboards-dir = ${:grafana-provisioning-config-dir}/dashboards
 telegraf-dir = ${:srv}/telegraf
 telegraf-extra-config-dir = ${:telegraf-dir}/extra-config
-
+loki-dir = ${:srv}/loki
+loki-storage-boltdb-dir = ${:loki-dir}/index/
+loki-storage-filesystem-dir = ${:loki-dir}/chunks/
+promtail-dir = ${:srv}/promtail
 
 # macros
 [generate-certificate]
@@ -75,7 +78,11 @@ extensions = jinja2.ext.do
 module = check_port_listening
 name = ${:_buildout_section_name_}.py
 
-
+[check-url-available-promise]
+recipe = slapos.cookbook:check_url_available
+path = ${directory:promise}/${:_buildout_section_name_}
+dash_path = {{ dash_bin }}
+curl_path = {{ curl_bin }}
 
 [influxdb]
 ipv6 = ${instance-parameter:ipv6-random}
@@ -133,6 +140,7 @@ data-dir = ${directory:grafana-data-dir}
 logs-dir = ${directory:grafana-logs-dir}
 plugins-dir = ${directory:grafana-plugins-dir}
 provisioning-config-dir = ${directory:grafana-provisioning-config-dir}
+provisioning-datasources-dir = ${directory:grafana-provisioning-datasources-dir}
 admin-user = ${grafana-password:username}
 admin-password = ${grafana-password:passwd}
 secret-key = ${grafana-secret-key:passwd}
@@ -160,6 +168,15 @@ context =
   section grafana grafana
   section apache_frontend apache-frontend
   key slapparameter_dict slap-configuration:configuration
+depends =
+  ${grafana-provisioning-config-file:rendered}
+
+[grafana-provisioning-config-file]
+<= config-file
+rendered = ${grafana:provisioning-datasources-dir}/datasource.yaml
+context =
+  section influxdb influxdb
+  section loki loki
 
 [grafana-listen-promise]
 <= check-port-listening-promise
@@ -183,6 +200,53 @@ context =
   section telegraf telegraf
 
 
+[loki]
+recipe = slapos.cookbook:wrapper
+command-line =
+   bash -c 'nice -19 chrt --idle 0 ionice -c3 {{ loki_bin }} -config.file=${loki-config-file:rendered}'
+wrapper-path = ${directory:service}/loki
+
+storage-boltdb-dir = ${directory:loki-storage-boltdb-dir}
+storage-filesystem-dir = ${directory:loki-storage-filesystem-dir}
+ip = ${instance-parameter:ipv4-random}
+port = 3100
+url = http://${:ip}:${:port}
+
+
+[loki-config-file]
+<= config-file
+context =
+  section loki loki
+
+[loki-listen-promise]
+<= check-url-available-promise
+url = ${loki:url}/ready
+
+[promtail]
+recipe = slapos.cookbook:wrapper
+command-line =
+   bash -c 'nice -19 chrt --idle 0 ionice -c3 {{ promtail_bin }} -config.file=${promtail-config-file:rendered}'
+wrapper-path = ${directory:service}/promtail
+
+dir = ${directory:promtail-dir}
+http_port = 19080
+ip = ${instance-parameter:ipv4-random}
+url = http://${:ip}:${:http_port}
+
+[promtail-config-file]
+<= config-file
+context =
+  section promtail promtail
+  section loki loki
+  key slapparameter_dict slap-configuration:configuration
+
+[promtail-listen-promise]
+<= check-port-listening-promise
+hostname= ${promtail:ip}
+port = ${promtail:http_port}
+
+
+
 [apache-frontend]
 <= slap-connection
 recipe = slapos.cookbook:requestoptional
@@ -201,6 +265,8 @@ instance-promises =
   ${influxdb-listen-promise:path}
   ${influxdb-password-promise:wrapper-path}
   ${grafana-listen-promise:path}
+  ${loki-listen-promise:path}
+  ${promtail-listen-promise:path}
 
 
 [publish-connection-parameter]
@@ -213,4 +279,6 @@ telegraf-extra-config-dir = ${telegraf:extra-config-dir}
 grafana-url = ${grafana:url}
 grafana-username = ${grafana:admin-user}
 grafana-password = ${grafana:admin-password}
+loki-url = ${loki:url}
+promtail-url = ${promtail:url}
 url = ${apache-frontend:connection-secure_access}

software/grafana/loki-config-file.cfg.in

+auth_enabled: false
+
+server:
+  http_listen_port: {{ loki['port'] }}
+
+ingester:
+  lifecycler:
+    address: {{ loki['ip'] }}
+    ring:
+      kvstore:
+        store: inmemory
+      replication_factor: 1
+  chunk_idle_period: 15m
+
+schema_config:
+  configs:
+  - from: 2018-04-15
+    store: boltdb
+    object_store: filesystem
+    schema: v9
+    index:
+      prefix: index_
+      period: 168h
+
+storage_config:
+  boltdb:
+    directory: {{ loki['storage-boltdb-dir'] }}
+
+  filesystem:
+    directory: {{ loki['storage-filesystem-dir'] }}
+
+limits_config:
+  enforce_metric_name: false
+  reject_old_samples: true
+  reject_old_samples_max_age: 168h
+
+chunk_store_config:
+  max_look_back_period: 0
+
+table_manager:
+  chunk_tables_provisioning:
+    inactive_read_throughput: 0
+    inactive_write_throughput: 0
+    provisioned_read_throughput: 0
+    provisioned_write_throughput: 0
+  index_tables_provisioning:
+    inactive_read_throughput: 0
+    inactive_write_throughput: 0
+    provisioned_read_throughput: 0
+    provisioned_write_throughput: 0
+  retention_deletes_enabled: false
+  retention_period: 0

software/grafana/promtail-config-file.cfg.in

+# https://github.com/grafana/loki/blob/master/docs/logentry/processing-log-lines.md
+
+server:
+  http_listen_port: {{ promtail['http_port'] }}
+  # XXX this external_url does not work ... promtail still listen on all IPs
+  external_url: {{ promtail['url'] }}
+  grpc_listen_port: 0
+
+positions:
+  filename: {{ promtail['dir'] }}/positions.yaml
+
+clients:
+  - url: {{ loki['url'] }}/api/prom/push
+
+scrape_configs:
+- job_name: test
+  static_configs:
+  - targets:
+      - localhost
+    labels:
+      job: grafanalogs
+      __path__: ./var/log/*log
+{{ slapparameter_dict.get('promtail-extra-scrape-config', '') }}

software/grafana/software.cfg

@@ -6,6 +6,8 @@ extends =
   ../../component/make/buildout.cfg
   ../../component/golang/buildout.cfg
   ../../component/openssl/buildout.cfg
+  ../../component/curl/buildout.cfg
+  ../../component/dash/buildout.cfg
   buildout.hash.cfg
   gowork.cfg
 
@@ -17,6 +19,9 @@ parts =
   influxdb-config-file
   telegraf-config-file
   grafana-config-file
+  grafana-provisioning-config-file
+  loki-config-file
+  promtail-config-file
 
 
 [nodejs]
@@ -31,7 +36,7 @@ md5sum = 46790033c23803387890f545e4040690
 
 
 [gowork]
-# All the softwares installed in the go work have "non standard" installation
+# All the softwares installed in the go workspace have "non standard" installation
 # methods, so we install them in specific parts with custom commands.
 # They will be installed because they are dependencies of ${gowork.goinstall}
 install =
@@ -41,6 +46,8 @@ influx-bin = ${:bin}/influx
 influxd-bin = ${:bin}/influxd
 grafana-bin = ${:bin}/grafana-server
 grafana-homepath = ${go_github.com_grafana_grafana:location}
+loki-bin = ${:bin}/loki
+promtail-bin = ${:bin}/promtail
 
 # use recent go
 golang  = ${golang1.12:location}
@@ -52,17 +59,22 @@ depends =
    ${influxdb-install:recipe}
    ${telegraf-install:recipe}
    ${grafana-install:recipe}
+   ${loki-install:recipe}
+   ${promtail-install:recipe}
 
 [influxdb-install]
 <= gowork.goinstall
 command = bash -c ". ${gowork:env.sh} && \
+   go install -v github.com/golang/dep/cmd/dep && \
    cd ${gowork:directory}/src/github.com/influxdata/influxdb && \
+   dep ensure && \
    go install ./cmd/..."
 update-command =
 
 [telegraf-install]
 <= gowork.goinstall
 command = bash -c ". ${gowork:env.sh} && \
+   go install -v github.com/golang/dep/cmd/dep && \
    cd ${gowork:directory}/src/github.com/influxdata/telegraf && \
    ${make:location}/bin/make &&
    cp telegraf ${gowork:bin}"
@@ -74,12 +86,32 @@ update-command =
 command = bash -c "export PATH=${nodejs:location}/bin/:$PATH && \
    . ${gowork:env.sh} && \
    cd ${gowork:directory}/src/github.com/grafana/grafana && \
-   ${gowork:golang}/bin/go run build.go setup && \
-   ${gowork:golang}/bin/go run build.go build && \
+   go run build.go setup && \
+   go run build.go build && \
    ${yarn:location}/bin/yarn install --pure-lockfile && \
    ${nodejs:location}/bin/npm run build"
 update-command =
 
+[loki-install]
+<= gowork.goinstall
+# loki also uses nodejs
+command = bash -c "export PATH=${nodejs:location}/bin/:$PATH && \
+   . ${gowork:env.sh} && \
+   go install -v github.com/golang/dep/cmd/dep && \
+   cd ${gowork:directory}/src/github.com/grafana/loki && \
+   go install ./cmd/loki"
+update-command =
+
+[promtail-install]
+<= gowork.goinstall
+# CGO_ENABLED is to disable systemd support (did not compile in my case)
+command = bash -c "export CGO_ENABLED=0 && \
+   . ${gowork:env.sh} && \
+   go install -v github.com/golang/dep/cmd/dep && \
+   cd ${gowork:directory}/src/github.com/grafana/loki && \
+   go install ./cmd/promtail"
+update-command =
+
 
 [download-file-base]
 recipe = slapos.recipe.build:download
@@ -96,6 +128,15 @@ mode = 0644
 [grafana-config-file]
 <= download-file-base
 
+[grafana-provisioning-config-file]
+<= download-file-base
+
+[loki-config-file]
+<= download-file-base
+
+[promtail-config-file]
+<= download-file-base
+
 [instance-profile]
 recipe = slapos.recipe.template:jinja2
 template = ${:_profile_base_location_}/${:filename}
@@ -110,10 +151,14 @@ context =
   key influx_bin gowork:influx-bin
   key grafana_bin gowork:grafana-bin
   key grafana_homepath gowork:grafana-homepath
+  key loki_bin gowork:loki-bin
+  key promtail_bin gowork:promtail-bin
+  key curl_bin :curl-bin
+  key dash_bin :dash-bin
   key monitor_template monitor2-template:rendered
-
+curl-bin = ${curl:location}/bin/curl
+dash-bin = ${dash:location}/bin/dash
 
 [versions]
 slapos.recipe.template = 4.2
 inotifyx = 0.2.2
-

software/grafana/test/README.md

+Tests for Grafana software release

software/grafana/test/setup.py

+##############################################################################
+#
+# Copyright (c) 2018 Nexedi SA and Contributors. All Rights Reserved.
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsibility of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# guarantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 3
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+from setuptools import setup, find_packages
+
+version = '0.0.1.dev0'
+name = 'slapos.test.grafana'
+long_description = open("README.md").read()
+
+setup(
+    name=name,
+    version=version,
+    description="Test for SlapOS' Grafana",
+    long_description=long_description,
+    long_description_content_type='text/markdown',
+    maintainer="Nexedi",
+    maintainer_email="info@nexedi.com",
+    url="https://lab.nexedi.com/nexedi/slapos",
+    packages=find_packages(),
+    install_requires=[
+        'slapos.core',
+        'slapos.libnetworkcache',
+        'erp5.util',
+        'requests',
+        'supervisor',
+        'psutil',
+    ],
+    zip_safe=True,
+    test_suite='test',
+)

software/grafana/test/test.py

+##############################################################################
+#
+# Copyright (c) 2019 Nexedi SA and Contributors. All Rights Reserved.
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsibility of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# guarantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 3
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import os
+import textwrap
+import logging
+import tempfile
+import time
+
+import requests
+
+from slapos.testing.testcase import makeModuleSetUpAndTestCaseClass
+
+
+setUpModule, SlapOSInstanceTestCase = makeModuleSetUpAndTestCaseClass(
+    os.path.abspath(
+        os.path.join(os.path.dirname(__file__), '..', 'software.cfg')))
+
+
+class TestGrafana(SlapOSInstanceTestCase):
+  def setUp(self):
+    self.grafana_url = self.computer_partition.getConnectionParameterDict(
+    )['grafana-url']
+
+  def test_grafana_available(self):
+    resp = requests.get(self.grafana_url, verify=False)
+    self.assertEqual(requests.codes.ok, resp.status_code)
+
+  def test_grafana_api(self):
+    # check API is usable
+    api_org_url = '{self.grafana_url}/api/org'.format(**locals())
+    resp = requests.get(api_org_url, verify=False)
+    self.assertEqual(requests.codes.unauthorized, resp.status_code)
+
+    connection_params = self.computer_partition.getConnectionParameterDict()
+    resp = requests.get(
+        api_org_url,
+        verify=False,
+        auth=requests.auth.HTTPBasicAuth(
+            connection_params['grafana-username'],
+            connection_params['grafana-password'],
+        ))
+    self.assertEqual(requests.codes.ok, resp.status_code)
+    self.assertEqual(1, resp.json()['id'])
+
+  def test_grafana_datasource_povisinonned(self):
+    # data sources are provisionned
+    connection_params = self.computer_partition.getConnectionParameterDict()
+    resp = requests.get(
+        '{self.grafana_url}/api/datasources'.format(**locals()),
+        verify=False,
+        auth=requests.auth.HTTPBasicAuth(
+            connection_params['grafana-username'],
+            connection_params['grafana-password'],
+        ))
+    self.assertEqual(requests.codes.ok, resp.status_code)
+    self.assertEqual(
+        sorted(['influxdb', 'loki']),
+        sorted([ds['type'] for ds in resp.json()]))
+
+
+class TestInfluxDb(SlapOSInstanceTestCase):
+  def setUp(self):
+    self.influxdb_url = self.computer_partition.getConnectionParameterDict(
+    )['influxdb-url']
+
+  def test_influxdb_available(self):
+    ping_url = '{self.influxdb_url}/ping'.format(**locals())
+    resp = requests.get(ping_url, verify=False)
+    self.assertEqual(requests.codes.no_content, resp.status_code)
+
+  def test_influxdb_api(self):
+    query_url = '{self.influxdb_url}/query'.format(**locals())
+    connection_params = self.computer_partition.getConnectionParameterDict()
+
+    for i in range(5):
+      # retry, as it may take a little delay to create databases
+      resp = requests.get(
+          query_url,
+          verify=False,
+          params=dict(
+              q='SHOW DATABASES',
+              u=connection_params['influxdb-username'],
+              p=connection_params['influxdb-password']))
+      self.assertEqual(requests.codes.ok, resp.status_code)
+      result, = resp.json()['results']
+      if result['series']:
+        break
+      time.sleep(0.5 * i)
+
+    self.assertIn(
+        [connection_params['influxdb-database']], result['series'][0]['values'])
+
+
+class TestTelegraf(SlapOSInstanceTestCase):
+  def test_telegraf_running(self):
+    with self.slap.instance_supervisor_rpc as supervisor:
+      all_process_info = supervisor.getAllProcessInfo()
+    process_info, = [p for p in all_process_info if 'telegraf' in p['name']]
+    self.assertEqual('RUNNING', process_info['statename'])
+
+
+class TestLoki(SlapOSInstanceTestCase):
+  @classmethod
+  def getInstanceParameterDict(cls):
+    cls._logfile = tempfile.NamedTemporaryFile(suffix='log')
+    return {
+        'promtail-extra-scrape-config':
+            textwrap.dedent(
+                r'''
+                - job_name: {cls.__name__}
+                  pipeline_stages:
+                  - match:
+                    selector: "{{job=~\".*\"}}"
+                    stages:
+                    - regex:
+                        expression: "^(?P<timestamp>.*) - (?P<name>\\S+) - (?P<level>\\S+) - (?P<message>.*)"
+                    - timestamp:
+                        format: 2006-01-02T15:04:05Z00:00
+                        source: timestamp
+                    - labels:
+                        level:
+                        name:
+                  static_configs:
+                  - targets:
+                      - localhost
+                    labels:
+                      job: {cls.__name__}
+                      __path__: {cls._logfile.name}
+                ''').format(**locals())
+    }
+
+  @classmethod
+  def tearDownClass(cls):
+    cls._logfile.close()
+    super(TestLoki, cls).tearDownClass()
+
+  def setUp(self):
+    self.loki_url = self.computer_partition.getConnectionParameterDict(
+    )['loki-url']
+
+  def test_loki_available(self):
+    self.assertEqual(
+        requests.codes.ok,
+        requests.get('{self.loki_url}/ready'.format(**locals()),
+                     verify=False).status_code)
+
+  def test_log_ingested(self):
+    # create a logger logging to the file that we have
+    # configured in instance parameter.
+    test_logger = logging.getLogger(self.id())  # type: logging.Logger
+    test_handler = logging.FileHandler(filename=self._logfile.name)
+    test_handler.setFormatter(
+        logging.Formatter(
+            '%(asctime)s - %(name)s - %(levelname)s - %(message)s'))
+    test_logger.addHandler(test_handler)
+    test_logger.info("testing message")
+    test_logger.info("testing another message")
+    test_logger.warning("testing warn")
+
+    # Check our messages have been ingested
+    # we retry a few times, because there's a short delay until messages are
+    # ingested and returned.
+    for i in range(10):
+      resp = requests.get(
+          '{self.loki_url}/api/prom/query?query={{job="TestLoki"}}'.format(
+              **locals()),
+          verify=False).json()
+      if not resp:
+        time.sleep(0.5 * i)
+        continue
+
+    warn_stream, = [stream for stream in resp['streams'] if 'level="WARNING"' in stream['labels']]
+    self.assertIn("testing warn", warn_stream['entries'][0]['line'])
+    info_stream, = [stream for stream in resp['streams'] if 'level="INFO"' in stream['labels']]
+    self.assertTrue(
+        [
+            line for line in info_stream['entries']
+            if "testing message" in line['line']
+        ])
+    self.assertTrue(
+        [
+            line for line in info_stream['entries']
+            if "testing another message" in line['line']
+        ])
+    # The labels we have configued are also available
+    resp = requests.get(
+        '{self.loki_url}/api/prom/label'.format(**locals()),
+        verify=False).json()
+    self.assertIn('level', resp['values'])
+    self.assertIn('name', resp['values'])