Connection refused with Python connection in Docker

Trying to install Elasticsearch and Kibana 8.4.3 Docker containers on a development laptop, and run elasticsearch-py commands from an app in another running container. And I'm stuck.

I have the ES8 and Kibana containers up, and can access ES from Kibana, create indexes, etc., but when I try to make a connection from the app container to the running ES instance with a python statement, I get "Connection refused" no matter what connection statement I use. E.g.

es = Elasticsearch( [{ 'host': '127.0.0.1', 'port': 9200,'scheme': 'https'}], ca_certs="./http_ca.crt", http_auth=('elastic', ${ELASTIC_PASSWORD}) )

The configuration and accessing of http_ca.crt seems to have something to do with it. Maybe I'm missing something about a network: config item; can't find documentation about when that is called for.

I have followed the instructions in the Elasticsearch docs explicitly: here, and took the docker-compose example there, removed references to nodes 2 and 3, and started the containers with

docker-compose -f docker-compose-esk.yml.

The environment variables are read from a .env file. I set the exposed ports to 9201 and 5602 respectively to avoid conflict with my non-Docker ES & Kibana installs running on the same laptop.

As I say, the following will get me accessing the container's ES instance with Kibana on localhost:5602

docker-compose-esk.yml

version: "2.2"

services:
  app:
    platform: linux/amd64
    container_name: 'whg-docker'
    build:
      context: .
      args:
        - DEV=true
    ports:
      - "8001:8000"
    volumes:
      - ./app:/app
    command: >
      sh -c "python manage.py wait_for_db &&
             python manage.py migrate &&
             python manage.py runserver 0.0.0.0:8000 &&
             celery -A whg worker -l INFO"
    environment:
      - DB_HOST=db
      - DB_NAME=devdb
      - DB_USER=devuser
      - DB_PASS=changeme
      - DEBUG=1
    depends_on:
      - db

  setup:
    image: docker.elastic.co/elasticsearch/elasticsearch:${STACK_VERSION}
    volumes:
      - certs:/usr/share/elasticsearch/config/certs
    user: "0"
    command: >
      bash -c '
        if [ x${ELASTIC_PASSWORD} == x ]; then
          echo "Set the ELASTIC_PASSWORD environment variable in the .env file";
          exit 1;
        elif [ x${KIBANA_PASSWORD} == x ]; then
          echo "Set the KIBANA_PASSWORD environment variable in the .env file";
          exit 1;
        fi;
        if [ ! -f config/certs/ca.zip ]; then
          echo "Creating CA";
          bin/elasticsearch-certutil ca --silent --pem -out config/certs/ca.zip;
          unzip config/certs/ca.zip -d config/certs;
        fi;
        if [ ! -f config/certs/certs.zip ]; then
          echo "Creating certs";
          echo -ne \
          "instances:\n"\
          "  - name: es01\n"\
          "    dns:\n"\
          "      - es01\n"\
          "      - localhost\n"\
          "    ip:\n"\
          "      - 127.0.0.1\n"\
          > config/certs/instances.yml;
          bin/elasticsearch-certutil cert --silent --pem -out config/certs/certs.zip --in config/certs/instances.yml --ca-cert config/certs/ca/ca.crt --ca-key config/certs/ca/ca.key;
          unzip config/certs/certs.zip -d config/certs;
        fi;
        echo "Setting file permissions"
        chown -R root:root config/certs;
        find . -type d -exec chmod 750 \{\} \;;
        find . -type f -exec chmod 640 \{\} \;;
        echo "Waiting for Elasticsearch availability";
        until curl -s --cacert config/certs/ca/ca.crt https://es01:9200 | grep -q "missing authentication credentials"; do sleep 30; done;
        echo "Setting kibana_system password";
        until curl -s -X POST --cacert config/certs/ca/ca.crt -u "elastic:${ELASTIC_PASSWORD}" -H "Content-Type: application/json" https://es01:9200/_security/user/kibana_system/_password -d "{\"password\":\"${KIBANA_PASSWORD}\"}" | grep -q "^{}"; do sleep 10; done;
        echo "All done!";
      '
    healthcheck:
      test: ["CMD-SHELL", "[ -f config/certs/es01/es01.crt ]"]
      interval: 1s
      timeout: 5s
      retries: 120

  es01:
    depends_on:
      setup:
        condition: service_healthy
    image: docker.elastic.co/elasticsearch/elasticsearch:${STACK_VERSION}
    volumes:
      - certs:/usr/share/elasticsearch/config/certs
      - esdata01:/usr/share/elasticsearch/data
    ports:
      - 9201:9200
    environment:
      - node.name=es01
      - cluster.name=${CLUSTER_NAME}
      - cluster.initial_master_nodes=es01
      - ELASTIC_PASSWORD=${ELASTIC_PASSWORD}
      - bootstrap.memory_lock=true
      - xpack.security.enabled=true
      - xpack.security.http.ssl.enabled=true
      - xpack.security.http.ssl.key=certs/es01/es01.key
      - xpack.security.http.ssl.certificate=certs/es01/es01.crt
      - xpack.security.http.ssl.certificate_authorities=certs/ca/ca.crt
      - xpack.security.http.ssl.verification_mode=certificate
      - xpack.security.transport.ssl.enabled=true
      - xpack.security.transport.ssl.key=certs/es01/es01.key
      - xpack.security.transport.ssl.certificate=certs/es01/es01.crt
      - xpack.security.transport.ssl.certificate_authorities=certs/ca/ca.crt
      - xpack.security.transport.ssl.verification_mode=certificate
      - xpack.license.self_generated.type=${LICENSE}
    mem_limit: ${MEM_LIMIT}
    ulimits:
      memlock:
        soft: -1
        hard: -1
    healthcheck:
      test:
        [
          "CMD-SHELL",
          "curl -s --cacert config/certs/ca/ca.crt https://localhost:9200 | grep -q 'missing authentication credentials'",
        ]
      interval: 10s
      timeout: 10s
      retries: 120

  kibana:
    depends_on:
      es01:
        condition: service_healthy
    image: docker.elastic.co/kibana/kibana:${STACK_VERSION}
    volumes:
      - certs:/usr/share/kibana/config/certs
      - kibanadata:/usr/share/kibana/data
    ports:
      - 5602:5601
    environment:
      - SERVERNAME=kibana
      - ELASTICSEARCH_HOSTS=https://es01:9200
      - ELASTICSEARCH_USERNAME=kibana_system
      - ELASTICSEARCH_PASSWORD=${KIBANA_PASSWORD}
      - ELASTICSEARCH_SSL_CERTIFICATEAUTHORITIES=config/certs/ca/ca.crt
    mem_limit: ${MEM_LIMIT}
    healthcheck:
      test:
        [
          "CMD-SHELL",
          "curl -s -I http://localhost:5601 | grep -q 'HTTP/1.1 302 Found'",
        ]
      interval: 10s
      timeout: 10s
      retries: 120

volumes:
  certs:
    driver: local
  esdata01:
    driver: local
  kibanadata:
    driver: local

After a couple days of trying many things, realized the docker-compose file was establishing names and paths for certs, and that a connection parameter need to point to the right cert. Two were created: .../config/certs/es01/es01.crt and .../config/certs/ca/ca.crt. First didn't work, second did. The ca.crt file had to be copied out of its location in the es01 container into the root of the "calling" container.

A working connection string turned out to be

es = Elasticsearch("https://es01:9200", ca_certs="ca.crt", http_auth=("elastic", "password"))

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