Functions Framework for C++
APACHE-2.0 License
Functions Framework | Unit Tests | Lint Test | Conformance Tests |
---|---|---|---|
C++ |
An open source FaaS (Functions as a Service) framework for writing portable C++ functions -- brought to you by Google.
The Functions Framework lets you write lightweight functions that run in many different environments, including:
Google Cloud Functions does not currently provide an officially supported C++ language runtime, but we're working to make running on Google Cloud Run as seamless and symmetric an experience as possible for your C++ Functions Framework projects.
The framework allows you to go from:
#include <google/cloud/functions/function.h>
namespace gcf = ::google::cloud::functions;
gcf::Function HelloWorld() {
return gcf::MakeFunction([](gcf::HttpRequest const& /*request*/) {
return gcf::HttpResponse{}
.set_header("Content-Type", "text/plain")
.set_payload("Hello World\n");
});
}
To:
curl https://<your-app-url>
# Output: Hello, World!
All without needing to worry about writing an HTTP server or request handling logic.
See more demos under the examples directory.
This library is considered generally available. We do not expect breaking changes to its public APIs. See below for a description of what is included in the public API, and what parts of the library may change without notice.
This library does not follow the Semantic Versioning conventions.
This is a C++17-based framework. It requires a compiler supporting C++17, we routinely test with GCC (>= 8), and with Clang (>= 10), let us know if you have problems with other compilers. The framework also depends on a number of other libraries, note that these libraries may have their own dependencies:
Library | Minimum version | Description |
---|---|---|
Abseil | 20200923 | C++ components to augment the standard library |
Boost | 1.73 | Peer-reviewed portable C++ libraries |
nlohmann/json | 3.9.1 | JSON for Modern C++ |
The examples use additional libraries, note that these libraries may have their own dependencies:
Library | Minimum version | Description |
---|---|---|
google-cloud-cpp | 1.23.0 | Google Cloud C++ Client Libraries |
{fmt} | 7.1.3 | A formatting library |
In general, we avoid making backwards incompatible changes to our C++ APIs (see
below for the definition of "API"). Sometimes such changes yield benefits to
our customers, in the form of better performance, easier-to-understand APIs,
and/or more consistent APIs across services. When these benefits warrant it, we
will announce these changes prominently in our CHANGELOG.md
file and in the
affected release's notes. Nevertheless, though we take commercially reasonable
efforts to prevent this, it is possible that backwards incompatible changes go
undetected and, therefore, undocumented. We apologize if this is the case and
welcome feedback (or bug reports) to rectify the problem.
By "API" we mean the C++ API exposed by public header files in this repo. We are not talking about the gRPC or REST APIs exposed by Google Cloud servers. We are also talking only about API stability -- the ABI is subject to change without notice. You should not assume that binary artifacts (e.g. static libraries, shared objects, dynamically loaded libraries, object files) created with one version of the library are usable with newer/older versions of the library. The ABI may, and does, change on "minor revisions", and even patch releases.
We request that our customers adhere to the following guidelines to avoid accidentally depending on parts of the library we do not consider to be part of the public API and therefore may change (including removal) without notice:
google/cloud/functions/*.h
,google/cloud/functions/mock/*.h
patterns.google/cloud/functions/internal
.Previous versions of the library will remain available on the GitHub Releases page.
Applications developers interact with a C++ library through more than just the C++ symbols and headers. They also need to reference the name of the library in their build scripts. Depending of the build system they use this may be a CMake target, a Bazel rule, a pkg-config module, or just the name of some object in the file system.
As with the C++ API, we try to avoid breaking changes to these interface
points. Sometimes such changes yield benefits to our customers, in the form of
easier-to-understand what names go with services, or more consistency
across services. When these benefits warrant it, we will announce these changes
prominently in our CHANGELOG.md
file and in the affected release's notes.
Nevertheless, though we take commercially reasonable efforts to prevent this,
it is possible that backwards incompatible changes go undetected and,
therefore, undocumented. We apologize if this is the case and welcome feedback
(or bug reports) to rectify the problem.
From time to time we add libraries to functions-framework-cpp
to validate
new designs, expose experimental (or otherwise not generally available)
features, or simply because a library is not yet complete. Such libraries
will have experimental
in their CMake target and Bazel rule. The README
file for these libraries will also document that they are experimental.
Such libraries are subject to change, including removal, without notice.
This includes, but it is not limited to, all their symbols, pre-processor
macros, files, targets, rules, and installed artifacts.
Only CMake packages starting with the functions_framework_cpp_
prefix are
intended for customer use. Only targets starting with
functions-framework-cpp::
are intended for customer use. Experimental targets
have experimental
in their name (e.g.
functions-framework-cpp::experimental-foo
), as previously stated,
experimental targets are subject to change or removal without notice.
Only modules starting with functions_framework_cpp_
are intended for customer
use.
We try to provide stable names for the previously described mechanisms:
find_package()
,It is certainly possible to use the library through other mechanisms, and while these may work, we may accidentally break these from time to time. Examples of such, and the recommended alternatives, include:
CMake's FetchContent
and/or git submodules: in these approaches the
functions-framework-cpp
library becomes a sub-directory of a larger CMake
build. We do not test functions-framework-cpp
in this configuration, and we
find it brittle as all CMake targets become visible to the larger
project. This is both prone to conflicts, and makes it impossible to enforce
that some targets are only for testing or implementation. Applications may
want to consider source package managers, such as vcpkg
, or CMake super
builds via ExternalProject_Add()
as alternatives.
Using library names directly: applications should not use the
library names, e.g., by using -lfunctions_framework_cpp
in build scripts. We
may need to split or merge libraries over time, making such names unstable.
Applications should use CMake targets, e.g.,
functions-framework-cpp::framework
, or pkg-config modules, e.g.,
$(pkg-config functions_framework_cpp --libs)
.
The documentation (and its links) is intended for human consumption and not third party websites, or automation (such as scripts scrapping the contents). The contents and links of our documentation may change without notice.
We think this covers all interface points, if we missed something please file a GitHub issue.
See CONTRIBUTING.md
for details on how to contribute to
this project, including how to build and test your changes as well as how to
properly format your code.
Apache 2.0; see LICENSE
for details.