502 Proxy Error ( docker + traefik + apache )
Question
I'm trying to setup traefik for SSL termination on my local development instance. Following up this guide I have the following configuration.
docker-compose.yml
version: '2.1'
services:
mariadb:
image: wodby/mariadb:10.2-3.0.2
healthcheck:
test: "/usr/bin/mysql --user=dummyuser --password=dummypasswd --execute \"SHOW DATABASES;\" | grep database"
interval: 3s
timeout: 1s
retries: 5
restart: always
environment:
MYSQL_ROOT_PASSWORD: dummy
MYSQL_DATABASE: database
volumes:
- ./mariadb-init:/docker-entrypoint-initdb.d # Place init .sql file(s) here.
- mysql:/var/lib/mysql # I want to manage volumes manually.
php:
depends_on:
mariadb:
condition: service_healthy
ports:
- "25:25"
- "587:587"
environment:
PHP_FPM_CLEAR_ENV: "no"
DB_HOST: mariadb
#DB_USER: dummy
DB_PASSWORD: dummypasswd
DB_NAME: database
DB_DRIVER: mysql
PHP_POST_MAX_SIZE: "256M"
PHP_UPLOAD_MAX_FILESIZE: "256M"
PHP_MAX_EXECUTION_TIME: 300
volumes:
- codebase:/var/www/html/
- private:/var/www/html/private
solr:
image: mxr576/apachesolr-4.x-drupal-docker
ports:
- "8983:8983"
labels:
- 'traefik.backend=solr'
- 'traefik.port=8983'
# - 'traefik.frontend.rule=Host:192.168.33.10'
volumes:
- solr:/opt/solr/example/solr/collection1/data
restart: always
portainer:
image: portainer/portainer
command: --no-auth -H unix:///var/run/docker.sock
volumes:
- /var/run/docker.sock:/var/run/docker.sock
labels:
- 'traefik.backend=portainer'
- 'traefik.port=9000'
restart: always
apache:
image: wodby/php-apache:2.4-2.0.2
# ports:
# - "80:80"
depends_on:
- php
environment:
APACHE_LOG_LEVEL: warn
APACHE_BACKEND_HOST: php
APACHE_SERVER_ROOT: /var/www/html/drupal
volumes:
- codebase:/var/www/html/
- private:/var/www/html/private
labels:
- 'traefik.backend=apache'
- 'traefik.docker.network=proxy'
- "traefik.frontend.rule=Host:127.0.0.1"
- "traefik.enable=true"
- "traefik.port=80"
- "traefik.default.protocol=http"
restart: always
networks:
- proxy
traefik:
image: traefik
command: -c /traefik.toml --web --docker --logLevel=INFO
ports:
- '80:80'
- '443:443'
- '8888:8080' # Dashboard
volumes:
- /var/run/docker.sock:/var/run/docker.sock
- /codebase/traefik.toml:/traefik.toml
- /codebase/certs/cert.crt:/cert.crt
- /codebase/certs/cert.key:/cert.key
volumes:
solr:
external: true
mysql:
external: true
codebase:
external: true
private:
external: true
networks:
proxy:
external: true
traefik.toml
logLevel = "DEBUG" # <---
defaultEntryPoints = ["https", "http"] # <---
[accessLog]
[traefikLog]
[entryPoints]
[entryPoints.http]
address = ":80"
[entryPoints.http.redirect]
entryPoint = "https"
[entryPoints.https]
address = ":443"
[entryPoints.https.tls]
[[entryPoints.https.tls.certificates]]
certFile = "/cert.crt"
keyFile = "/cert.key"
[retry]
[docker]
endpoint = "unix:///var/run/docker.sock"
watch = true
exposedbydefault = false
When trying to verify the instance, I get a 502 Bad Gateway
curl -i -k https://127.0.0.1
HTTP/1.1 502 Bad Gateway
Content-Length: 392
Content-Type: text/html; charset=iso-8859-1
Date: Fri, 14 Sep 2018 16:34:36 GMT
Server: Apache/2.4.29 (Unix) LibreSSL/2.5.5
X-Content-Type-Options: nosniff
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>502 Proxy Error</title>
</head><body>
<h1>Proxy Error</h1>
<p>The proxy server received an invalid
response from an upstream server.<br />
The proxy server could not handle the request <em><a href="/index.php">GET /index.php</a></em>.<p>
Reason: <strong>DNS lookup failure for: php</strong></p></p>
</body></html>
A reset for docker-compose and the docker network didn't help. I've checked the issue on their repo and it seems like nobody got a definitive solution. Anybody has an idea on how to solve this?
Edit:Update for full docker-compose file.
1 answers
solution1
0 ACCPTED 2018-09-16 12:29:31
You are trying to connect to php container from apache service using service discovery. But php container is not attached to the network proxy , Because you haven't declared network for it. The same case is with mariabd as well. So, When you connect to apache/traefik they look for host php which is not attached to the network proxy and throw error 502 .
Unless and until you specify external network, Docker containers will not be connected to them.
Hence, You have to specify the network as follows for all the services in order to make docker service discovery work properly.
networks:
- proxy
Bonus:
Since you have done port mapping. You can also use public Ip of your host machine followed by the port to connect to services from docker container and from outside containers as well.
Example:
Let us assume your ip is
192.168.0.123then you can connect tophpfrom any services in docker container and even from outside docker as192.168.0.123:25and192.168.0.123:587. This is because you have exposed ports 25,587 by mapping them to host ports 25,587 .
Some references:
- Docker networking
- Networking using the host network
- Connect a container to a user-defined bridge
- Networking with standalone containers
- Service discovery
- Networking in Compose (check "Specify custom networks" section)
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