92 lines
3.8 KiB
Markdown
92 lines
3.8 KiB
Markdown
serve_header.py
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===============
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Serves the `single_include/nlohmann/json.hpp` header file over HTTP(S).
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The header file is automatically amalgamated on demand.
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## Prerequisites
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1. Make sure these Python packages are installed.
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```
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PyYAML
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watchdog
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```
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(see `tools/serve_header/requirements.txt`)
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2. To serve the header over HTTPS (which is required by Compiler Explorer at this time), a certificate is needed.
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The recommended method for creating a locally-trusted certificate is to use [`mkcert`](https://github.com/FiloSottile/mkcert).
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- Install the `mkcert` certificate authority into your trust store(s):
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```
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$ mkcert -install
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```
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- Create a certificate for `localhost`:
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```
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$ mkcert localhost
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```
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The command will create two files, `localhost.pem` and `localhost-key.pem`, in the current working directory. It is recommended to create them in the top level or project root directory.
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## Usage
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`serve_header.py` has a built-in default configuration that will serve the `single_include/nlohmann/json.hpp` header file relative to the top level or project root directory it is homed in.
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The built-in configuration expects the certificate `localhost.pem` and the private key `localhost-key.pem`to be located in the top level or project root directory.
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To start serving the `json.hpp` header file at `https://localhost:8443/json.hpp`, run this command from the top level or project root directory:
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```
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$ make serve_header
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```
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Open [Compiler Explorer](https://godbolt.org/) and try it out:
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```cpp
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#include <https://localhost:8443/json.hpp>
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using namespace nlohmann;
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#include <iostream>
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int main() {
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// these macros are dynamically injected into the header file
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std::cout << JSON_BUILD_TIME << " (" << JSON_BUILD_COUNT << ")\n";
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return 0;
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}
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```
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> `serve_header.py` dynamically injects the macros `JSON_BUILD_COUNT` and `JSON_BUILD_TIME` into the served header file. By comparing build count or time output from the compiled program with the output from `serve_header.py`, one can be reasonably sure the compiled code uses the expected revision of the header file.
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## Configuration
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`serve_header.py` will try to read a configuration file `serve_header.yml` in the top level or project root directory, and will fall back on built-in defaults if the file cannot be read.
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An annotated example configuration can be found in `tools/serve_header/serve_header.yml.example`.
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## Serving `json.hpp` from multiple project directory instances or working trees
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`serve_header.py` was designed with the goal of supporting multiple project roots or working trees at the same time.
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The recommended directory structure is shown below but `serve_header.py` can work with other structures as well, including a nested hierarchy.
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```
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json/ ⮜ the parent or web server root directory
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├── develop/ ⮜ the main git checkout
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│ └── ...
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├── feature1/
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│ └── ... any number of additional
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├── feature2/ ⮜ working trees (e.g., created
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│ └── ... with git worktree)
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└── feature3/
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└── ...
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```
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To serve the header of each working tree at `https://localhost:8443/<worktree>/json.hpp`, a configuration file is needed.
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1. Create the file `serve_header.yml` in the top level or project root directory of any working tree:
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```yaml
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root: ..
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```
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By shifting the web server root directory up one level, the `single_include/nlohmann/json.hpp` header files relative to each sibling directory or working tree will be served.
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2. Start `serve_header.py` by running this command from the same top level or project root directory the configuration file is located in:
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```
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$ make serve_header
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```
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`serve_header.py` will automatically detect the addition or removal of working trees anywhere within the configured web server root directory.
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