build-mocker-image

When to use

Use when a mocker project must be containerized. Covers Dockerfile authoring, build/run/verify, and networking.

Steps

1. Verbatim Dockerfile (FB s14#6, LAB L5)

# build
FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
WORKDIR /src
COPY . .
RUN dotnet restore --configfile NuGet.config
RUN dotnet publish -c Release -o /app

# runtime — MUST be aspnet (mocker hosts an HTTP server); dotnet/runtime:10.0 FAILS at start
FROM mcr.microsoft.com/dotnet/aspnet:10.0
WORKDIR /app
COPY --from=build /app .
ENTRYPOINT ["dotnet", "HelloMocker.dll", "mocker.qaas.yaml"]

CRITICAL: runtime stage MUST be aspnet:10.0. Using runtime:10.0 fails at container start: Framework 'Microsoft.AspNetCore.App' ... No frameworks were found. (FB s13#7, LAB L5).

Dockerfile comments must be on their OWN line (FB s13#18). Never append a trailing comment to an instruction line — FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build # note fails the build with dockerfile parse error ... FROM requires either one or three arguments. Put # ... on a separate line.

2. Airgap build args (FB s08, docs deployMock.md)

For Artifactory feed, pass build args at build time:

docker build `
  --build-arg QAAS_NUGET_SOURCE_NAME=QaaS `
  --build-arg QAAS_NUGET_SOURCE_URL=https://artifactory.example.com/nuget/v3/index.json `
  -t hellomocker:lab .

NuGet.config template using these args:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageSources>
    <clear />
    <add key="${QAAS_NUGET_SOURCE_NAME}" value="${QAAS_NUGET_SOURCE_URL}" />
  </packageSources>
</configuration>

Some scaffolds use ENTRYPOINT ["sh","-c","exec dotnet DummyAppMock.dll \"$QAAS_MOCKER_CONFIG\""] for runtime config override (FB s14#6).

3. .dockerignore

obj/
bin/
allure-results/
session-data/
*.user

4. Mocker YAML for container: disable IsLocalhost

Servers:
  - Http:
      Port: 8080
      # IsLocalhost: false  ← omit or explicitly false → binds 0.0.0.0 (accessible from host)
      # IsLocalhost: true   ← WRONG in a container; binds 127.0.0.1 only (FB s03)

5. Build and run sequence

cd Mocker                                         # must be in the Dockerfile context dir

docker build -t hellomocker:lab .
# exit 0 = success

docker run -d -p 8080:8080 --name hellomocker hellomocker:lab
# -d = detached; -p host:container port mapping

docker logs hellomocker
# Look for:
# "Building transaction stub 'X' with processor 'Y'"
# "Built 4 transaction stub(s) including default not-found and internal-error stubs"
# "HTTP Server started. Listening on http://0.0.0.0:8080"
# "controller enabled: False"  (or True if Controller configured)

Expected startup log lines (FB s14#6, LAB L5):

• Building transaction stub 'HealthStub' with processor 'HealthProcessor'
• Built 4 transaction stub(s) including default not-found and internal-error stubs
• Resolved runtime graph with 0 data source(s), 4 stub(s), 1 server(s) [Http], and controller enabled: False
• HTTP Server started. Listening on http://0.0.0.0:8080

6. Verify curl

curl.exe -s -w "\n%{http_code}" http://127.0.0.1:8080/hello
# Expected: body + 200

curl.exe -s -o NUL -w "%{http_code}" http://127.0.0.1:8080/health
# Expected: 200

7. Controller Redis from inside container (FB s14#7, LAB L6)

If mocker uses Controller, Redis host inside the container must reach the host machine:

Controller:
  ServerName: HelloMocker
  Redis:
    Host: "host.docker.internal:6379"   # NOT 127.0.0.1 (that is the container itself)

See references/container-networking.md for Docker network options.

8. Cleanup

docker stop hellomocker
docker rm hellomocker

9. Docker Compose (multi-service stack)

Run the mocker — plus any dependency it talks to (Redis/RabbitMQ) — as a compose stack. Inside a compose network, services reach each other by service name (e.g. Redis host redis:6379, NOT 127.0.0.1); the host reaches the mocker through the published port. Publish ONLY the service you curl from the host (the mocker). Publishing a dependency like Redis to a fixed host port (6379:6379) can clash with another container already bound to that port on the host — leave internal deps unpublished.

# docker-compose.yml
services:
  redis:                     # internal dependency — NOT published to the host
    image: redis:7-alpine    # other services reach it as host "redis" on 6379
  mocker:
    build: .                 # builds the Dockerfile in this directory
    ports: ["8125:8080"]     # ONLY the mocker is published (host:container; container stays on its YAML Port)
    depends_on: [redis]

docker compose -p qaas-e03 up -d --build      # build + start
curl.exe http://127.0.0.1:8125/health         # verify through the published host port
docker compose -p qaas-e03 down -v            # tear down (remove volumes)

10. CI build script

A thin, idempotent wrapper so CI can build (and optionally smoke-test) the image in one call. Keep the exact image tag the rest of the pipeline expects, and propagate the build exit code.

# build.ps1
docker build -t hellomocker:lab .
if ($LASTEXITCODE -ne 0) { Write-Error "image build failed"; exit 1 }

11. Env-driven config at run time

Use the sh -c ENTRYPOINT (FB s14#6) so the config file is chosen by an environment variable at docker run time instead of being baked into the image:

ENTRYPOINT ["sh", "-c", "exec dotnet Hello.dll \"$QAAS_MOCKER_CONFIG\""]

docker run -d -p 8127:8080 -e QAAS_MOCKER_CONFIG=hello.mocker.yaml hellomocker:lab

Traps

#	Trap	Fix
s13#7	runtime:10.0 base → aspnet crash	Use aspnet:10.0 in second FROM stage
s03	IsLocalhost:true in container	Omit or set false
s07	127.0.0.1 for Redis/broker inside container	Use host.docker.internal
s08	No NuGet.config → restore fails airgap	Include NuGet.config with <clear/> + Artifactory add
LAB L5	ENTRYPOINT DLL name wrong	Must match <AssemblyName> in csproj

Citations

• FB s13#7 (aspnet fix), FB s14#6 (verbatim Dockerfile), FB s03 (IsLocalhost), FB s08 (airgap/NuGet)