Init commit

.gitignore

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+server

Dockerfile

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+# Use the scratch base image
+FROM scratch
+
+WORKDIR /app
+COPY server .
+
+# Expose port 80
+EXPOSE 80
+
+# Run the binary
+CMD ["/app/server"]

LICENSE

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+MIT License
+
+Copyright (c) 2024 Kevin Midbøe
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Makefile

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+.PHONY: all docker-build run clean
+
+# Variables for C compilation
+CC = gcc
+CFLAGS = -Os -fdata-sections -ffunction-sections -march=native -Wall -Wextra
+TARGET = server
+
+# Variables for Docker Buildx
+IMAGE_NAME = kevinmidboe/http-200
+VERSION = latest
+PLATFORMS = linux/amd64,linux/arm64,linux/arm/v7
+DATE=$(shell date +%Y.%m.%d)
+
+# Default rule to compile the C program and build Docker image
+all: $(TARGET)
+
+run:
+	./server
+
+# Rule to compile the C executable
+$(TARGET): server.c
+	$(CC) $(CFLAGS) -o $(TARGET) server.c
+
+# Docker Buildx setup
+docker-setup: $(TARGET)
+	docker buildx create --use --name multiarch_builder || true
+	docker buildx inspect --bootstrap
+
+# Build multi-platform Docker image without pushing to registry
+docker-build: docker-setup
+	docker buildx build --platform $(PLATFORMS) -t $(IMAGE_NAME):$(VERSION) -t $(IMAGE_NAME):$(DATE) .
+
+# Build multi-platform Docker image and push to registry
+docker-publish: docker-setup
+	docker buildx build --platform $(PLATFORMS) -t $(IMAGE_NAME):$(VERSION) -t $(IMAGE_NAME):$(DATE) --push .
+
+# Clean up Buildx builder and compiled binary
+clean:
+	rm -f $(TARGET)
+	docker buildx rm multiarch_builder || true
+

README.md

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+# http-200
+
+Simple http C server that always responds 200 to all http requests. Resulting in docker image size smaller than 40 kB (or 3 kB compressed).
+
+## build
+
+```bash
+gcc -o server server.c
+```
+
+or using make
+
+```bash
+make
+```
+
+## run
+
+```bash
+./server
+```
+
+or
+
+```bash
+make run
+```
+
+## docker
+
+build using docker with
+
+```bash
+docker build -t http-200 .
+```
+
+publish (multi-arch) using
+
+```bash
+make docker-publish
+```

server.c

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+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <arpa/inet.h>  // For inet_ntop
+
+int server_fd;
+
+void handle_signal(int signal) {
+    printf("\nReceived signal %d, shutting down server...\n", signal);
+    fflush(stdout);  // Ensure output is flushed immediately
+    if (server_fd >= 0) {
+        close(server_fd);
+    }
+    exit(0);  // Graceful exit after closing the socket
+}
+
+int main() {
+    struct sockaddr_in address;
+    struct sockaddr_in client_address;
+    int client_fd;
+    int addrlen = sizeof(address);
+    int port = 80;
+
+    // Disable stdout buffering
+    setbuf(stdout, NULL);  // Disables buffering, output is immediate
+
+    // Setup signal handler for graceful shutdown
+    struct sigaction sa;
+    sa.sa_handler = handle_signal;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = 0;
+    sigaction(SIGINT, &sa, NULL);
+    sigaction(SIGTERM, &sa, NULL);
+
+    // Create socket
+    server_fd = socket(AF_INET, SOCK_STREAM, 0);
+    if (server_fd == 0) {
+        perror("Socket failed");
+        return 1;
+    }
+
+    // Configure the server address and port
+    address.sin_family = AF_INET;
+    address.sin_addr.s_addr = INADDR_ANY;
+    address.sin_port = htons(port);
+
+    // Bind the socket to the port
+    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
+        perror("Bind failed");
+        return 1;
+    }
+
+    // Start listening for incoming connections
+    if (listen(server_fd, 1) < 0) {
+        perror("Listen failed");
+        return 1;
+    }
+
+    // Output immediately after listening starts
+    printf("Server listening on port %i...\n", port);
+    fflush(stdout);  // Ensure output is flushed immediately
+
+    while (1) {
+        // Accept client connections
+        client_fd = accept(server_fd, (struct sockaddr *)&client_address, (socklen_t *)&addrlen);
+        if (client_fd < 0) {
+            perror("Accept failed");
+            continue;
+        }
+
+        // Get the client's IP address
+        char client_ip[INET_ADDRSTRLEN];
+        if (inet_ntop(AF_INET, &client_address.sin_addr, client_ip, sizeof(client_ip)) == NULL) {
+            perror("inet_ntop failed");
+        } else {
+            printf("Connection from IP: %s\n", client_ip);  // Log the client IP
+        }
+
+        // Send a simple HTTP 200 OK response
+        char response[] = "HTTP/1.1 200 OK\r\nContent-Length: 0\r\nserver: http-200\r\n\r\n";
+        send(client_fd, response, strlen(response), 0);
+        close(client_fd);  // Close the client connection after sending the response
+    }
+
+    return 0;
+}
+