I am running an ASP.NET Core 3.0 multi-container application on an Azure Linux App Service for Containers using Docker Compose. Containers are built and pushed to an Azure Container Registry via CI pipelines and CD pipelines deploy to the app service using a "docker-compose.[environment].yml".
I am trying to use nginx and jwilder's docker-gen as a reverse proxy (separate containers to avoid having the docker socket bound to a publicly exposed container service), and use virtual host names to access the various services over the net.
I seem to be going round in circles between the following 3 errors:
1. The web app displaying the 'Welcome to Nginx' page with logs repeating:
2020-02-26T15:18:44.021444322Z 2020/02/26 15:18:44 Watching docker events
2020-02-26T15:18:44.022275908Z 2020/02/26 15:18:44 Error retrieving docker server info: Get http://unix.sock/info: dial unix /tmp/docker.sock: connect: no such file or directory
2020-02-26T15:18:44.022669201Z 2020/02/26 15:18:44 Error listing containers: Get http://unix.sock/containers/json?all=1: dial unix /tmp/docker.sock: connect: no such file or directory
2020-02-26T15:18:44.405594944Z 2020/02/26 15:18:44 Docker daemon connection interrupted
2. 502 Bad Gateway
502 - Web server received an invalid response while acting as a gateway or proxy server. There is a problem with the page you are looking for, and it cannot be displayed. When the Web server (while acting as a gateway or proxy) contacted the upstream content server, it received an invalid response from the content server.
3. The app service's 'Application Error :(' page.
Here is my docker-compose.development.yml:
version: "3.7"
services:
nginx:
image: nginx
environment:
DEFAULT_HOST: ***.azurewebsites.net
ports:
- "80:80"
volumes:
- "${WEBAPP_STORAGE_HOME}/tmp/nginx:/etc/nginx/conf.d"
dockergen:
image: jwilder/docker-gen
command: -notify-sighup nginx -watch /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf
volumes_from:
- nginx
volumes:
- "/var/run/docker.sock:/tmp/docker.sock:ro"
- "${WEBAPP_STORAGE_HOME}./nginx.tmpl:/etc/docker-gen/templates/nginx.tmpl"
webapp:
image: ***.azurecr.io/digitalcore:dev
restart: always
environment:
VIRTUAL_HOST: ***.azurewebsites.net
depends_on:
- nginx
"webapp" service dockerfile (exposes ports 80, 443):
FROM mcr.microsoft.com/dotnet/core/sdk:3.0 AS build
WORKDIR /source
COPY . .
RUN dotnet restore
RUN dotnet publish --output /app/ --configuration Release --no-restore
FROM mcr.microsoft.com/dotnet/core/aspnet:3.0 AS runtime
WORKDIR /app
COPY --from=build /app .
EXPOSE 80 443
ENTRYPOINT ["dotnet", "DigitalCore.WebApp.dll"]
Error #1 seems to be the closest I have got to seeing it working, with the issues being centred around configuring the volumes correctly for an Azure Linux App Service (the ${WEBAPP_STORAGE_HOME} made an appearance after much digging).
Networks and Container Names only seemed to make things worse in my efforts so far, so they were removed to try and keep things to the bare essentials to get it working. The "webapp" service is where my focus is at the moment
Can anybody spot where I'm going wrong?! I will be eternally grateful for any words of wisdom...
UPDATE:
Some progress it would seem - after removing the "ro" permissions from the container volume, docker.sock is now being found, but docker-gen is unable to connect to the endpoint.
2020-02-26T22:21:44.186316399Z 2020/02/26 22:21:44 Watching docker events
2020-02-26T22:21:44.187487428Z 2020/02/26 22:21:44 Error retrieving docker server info: cannot connect to Docker endpoint
2020-02-26T22:21:44.188270247Z 2020/02/26 22:21:44 Error listing containers: cannot connect to Docker endpoint
2020-02-26T22:21:44.500471940Z 2020/02/26 22:21:44 Docker daemon connection interrupted
UPDATE 2
I have now built the containers and pushed to the Azure Container Registry so I am not pulling from different locations. This is my current docker-compose:
version: "3.7"
services:
nginx:
image: ***.azurecr.io/nginx:dev
ports:
- "80:80"
volumes:
- "${WEBAPP_STORAGE_HOME}/etc/nginx/conf.d"
dockergen:
image: ***.azurecr.io/dockergen:dev
privileged: true
command: -notify-sighup nginx -watch -only-exposed /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf
volumes_from:
- nginx
volumes:
- "${WEBAPP_STORAGE_HOME}/var/run/docker.sock:/tmp/docker.sock"
- "${WEBAPP_STORAGE_HOME}./nginx.tmpl:/etc/docker-gen/templates/nginx.tmpl"
webapp:
image: ***.azurecr.io/digitalcore:dev
restart: always
environment:
VIRTUAL_HOST: ***.azurewebsites.net
depends_on:
- nginx
