add the ready health check

.vscode/settings.json

@@ -2,6 +2,7 @@
     "cSpell.words": [
         "ASPNETCORE",
         "Edsger",
+        "healthz",
         "Heemstra",
         "opentelemetry",
         "opsi",

README.md

@@ -21,6 +21,11 @@ docker compose ps
 # show logs.
 docker compose logs
 
+# show the quotes container health check output log.
+docker inspect --format '{{json .State.Health }}' \
+  "$(docker compose ps quotes --format '{{.Name}}')" \
+  | jq -r '.Log[].Output'
+
 # open a container network interface in wireshark.
 ./wireshark.sh quotes
 

docker-compose.yml

@@ -22,4 +22,9 @@ services:
       # http api.
       # http://localhost:8000
       - 8000:8000
+    healthcheck:
+      test: ["CMD", "curl", "--silent", "--fail-with-body", "--max-time", "5", "http://localhost:8000/healthz/ready"]
+      interval: 15s
+      timeout: 5s
+      retries: 2
     restart: on-failure

quotes/Dockerfile

@@ -8,6 +8,13 @@ COPY . ./
 RUN dotnet publish -c Release
 
 FROM mcr.microsoft.com/dotnet/aspnet:8.0
+RUN <<'EOF'
+#!/bin/bash
+set -euxo pipefail
+apt-get update
+apt-get install -y --no-install-recommends curl
+rm -rf /var/lib/apt/lists/*
+EOF
 WORKDIR /app
 COPY --from=builder /app/bin/Release/net8.0/publish ./
 ENTRYPOINT ["/app/Quotes"]

quotes/Program.cs

@@ -1,4 +1,5 @@
 using System.Reflection;
+using Microsoft.AspNetCore.Diagnostics.HealthChecks;
 using OpenTelemetry.Logs;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.ResourceDetectors.Container;
@@ -7,6 +8,7 @@
 
 var builder = WebApplication.CreateBuilder(args);
 
+builder.Services.AddHealthChecks();
 builder.Services.AddControllers();
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen();
@@ -46,6 +48,8 @@
 
 var app = builder.Build();
 
+app.MapHealthChecks("/healthz/ready");
+
 // enable the swagger document endpoint and swagger ui.
 app.UseSwagger();   // make the swagger available at /swagger/v1/swagger.json
 app.UseSwaggerUI(); // make the swagger UI available at /swagger