Add docker setup for local testing

Dockerfile

@@ -0,0 +1,14 @@
+FROM python:3.8-slim
+
+USER root
+
+RUN mkdir /tmp/build
+WORKDIR /tmp/build
+COPY . .
+RUN SETUPTOOLS_SCM_PRETEND_VERSION=0 pip install .
+
+WORKDIR /tmp
+RUN rm -rf /tmp/build
+
+RUN useradd --system checker
+USER checker

README.rst

@@ -30,6 +30,21 @@ console scripts via the command line::
     chweb_collect -c config.yaml &
     chweb_consume -c config.yaml &
 
+Using docker-compose
+--------------------
+
+The services can be run with docker-compose. You'd need to change the values of
+``KAFKA_SERVERS``, ``POSTGRES_HOST`` and ``POSTGRES_PASS`` in order for
+the configuration to be properly applied. Also, you'd need to download the
+kafka certificates and put them in the folder you're running docker-composer
+from and create the PostgreSQL cert by copying it from aivens console and
+saving it to ``pgcert.pem``. After all this is done, simply run::
+
+    docker-compose up
+
+Config file
+===========
+
 Sites
 -----
 

docker-compose.yaml

@@ -0,0 +1,42 @@
+version: "3"
+services:
+  collector:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    environment:
+      KAFKA_SERVERS: "AIVEN_KAFKA_SERVER"
+      KAFKA_TOPIC: "sitestats"
+      KAFKA_CA_FILE: "/etc/kafka_ca.pem"
+      KAFKA_CERT: "/etc/kafka_service.cert"
+      KAFKA_KEY: "/etc/kafka_service.key"
+    volumes:
+    - ./config.yaml:/etc/checker.yaml
+    - ./ca.pem:/etc/kafka_ca.pem
+    - ./service.cert:/etc/kafka_service.cert
+    - ./service.key:/etc/kafka_service.key
+    command: chweb_collect
+
+  consumer:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    environment:
+      KAFKA_SERVERS: "AIVEN_KAFKA_SERVER"
+      KAFKA_TOPIC: "sitestats"
+      KAFKA_CA_FILE: "/etc/kafka_ca.pem"
+      KAFKA_CERT: "/etc/kafka_service.cert"
+      KAFKA_KEY: "/etc/kafka_service.key"
+      POSTGRES_DB: "defaultdb"
+      POSTGRES_HOST: "AIVEN_PG_SERVER"
+      POSTGRES_PORT: 23700
+      POSTGRES_USER: "avnadmin"
+      POSTGRES_PASS: ""
+      POSTGRES_CERT: "/etc/pgcert.pem"
+    volumes:
+    - ./config.yaml:/etc/checker.yaml
+    - ./ca.pem:/etc/kafka_ca.pem
+    - ./service.cert:/etc/kafka_service.cert
+    - ./service.key:/etc/kafka_service.key
+    - ./pgcert.pem:/etc/pgcert.pem
+    command: chweb_consume