Guides

C++ Boost

In this guide we create and deploy a C++-based HTTP web server using the Boost libraries. To run this example, follow these steps:

1. Install the kraft CLI tool and a container runtime engine, e.g. Docker.

2. Clone the example repository and cd into the examples/http-cpp-boost/ directory:

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git clone https://github.com/kraftcloud/examples
cd examples/http-cpp-boost/

Make sure to log into Unikraft Cloud by setting your token and a metro close to you. We use fra0 (Frankfurt, 🇩🇪) in this guide:

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# Set Unikraft Cloud access token
export UKC_TOKEN=token
# Set metro to Frankfurt, DE
export UKC_METRO=fra0

When done, invoke the following command to deploy this application on Unikraft Cloud:

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kraft cloud deploy -p 443:8080 .

The output shows the instance URL and other details:

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[●] Deployed successfully!
 │
 ├────────── name: http-cpp-boost-rae7s
 ├────────── uuid: 5a9886fa-f8a3-4860-afcf-d5eb13fdc38d
 ├───────── state: running
 ├─────────── url: https://red-snow-3bn7bzc8.fra0.kraft.host
 ├───────── image: http-cpp-boost@sha256:61cf86b89fed46351af53689e27189315e466576475f61c7240bf17644613489
 ├───── boot time: 15.00 ms
 ├──────── memory: 128 MiB
 ├─────── service: red-snow-3bn7bzc8
 ├── private fqdn: http-cpp-boost-rae7s.internal
 ├──── private ip: 172.16.6.4
 └────────── args: /http_server

In this case, the instance name is http-cpp-boost-rae7s and the URL is https://red-snow-3bn7bzc8.fra0.kraft.host. They are different for each run.

Use curl to query the Unikraft Cloud instance of the C++ Boost HTTP web server:

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curl https://red-snow-3bn7bzc8.fra0.kraft.host

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Hello, World!

At any point in time, you can list information about the instance:

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kraft cloud instance list

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NAME                  FQDN                                STATE    CREATED AT    IMAGE                                                         MEMORY   ARGS           BOOT TIME
http-cpp-boost-rae7s  red-snow-3bn7bzc8.fra0.kraft.host  running  1 minute ago  http-cpp-boost@sha256:61cf86b89fed46351af53689e27189315e...   128 MiB  /http_server   15000us

When done, you can remove the instance:

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kraft cloud instance remove http-cpp-boost-rae7s

Customize your Application

To customize the application, update the files in the repository, listed below:

• http_server.cpp: the C++ HTTP server
• Kraftfile: the Unikraft Cloud specification
• Dockerfile: the Docker-specified application filesystem

Lines in the Kraftfile have the following roles:

• spec: v0.6: The current Kraftfile specification version is 0.6.

• runtime: base: The Unikraft runtime kernel to use is its base one.

• rootfs: ./Dockerfile: Build the application root filesystem using the Dockerfile.

• cmd: ["/http_server"]: Use /http_server as the starting command of the instance.

Lines in the Dockerfile have the following roles:

• COPY ./http_server.cpp /src/http_server.cpp: Copy the server implementation file (http_server.cpp) in the Docker filesystem (in /src/http_server.cpp).

The following options are available for customizing the application:

• If only updating the implementation in the http_server.cpp source file, no other change is required.

• If new files are added, these have to be copied in the application filesystem, using the COPY command in the Dockerfile.

• If a new C++ source files is added, update the cmd line in the Kraftfile and replace http_server.cpp to run that file when creating the instance.

• More extensive changes may require expanding the Dockerfile with additional Dockerfile commands.

Learn More

Use the --help option for detailed information on using Unikraft Cloud:

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kraft cloud --help

Or visit the CLI Reference.