Within conanfile.py , this is how you can obtain a list of include & library directories for each of the dependencies:
class MyProject(Conanfile):
# ...
def build(self):
# Check dependencies
for dependency in self.dependencies.values():
cppinfo = dependency.cpp_info.aggregated_components()
print("libdirs", cppinfo.libdirs)
print("includedirs", cppinfo.includedirs)
# ...
When you try to download a package from conancenter using conan download, the right syntax to use is:
conan download libcurl/8.1.1 -r conancenter
If you forget to specify -r conancenter, you will see the following error message:
usage: conan download [-h] [-v [V]] [--only-recipe] [-p PACKAGE_QUERY] -r REMOTE reference conan download: error: the following arguments are required: -r/--remote ERROR: Exiting with code: 2
You want to install or build a conan project using a command such as
conan install .
but you see an error message such as
ERROR: The default build profile '/home/uli/.conan2/profiles/default' doesn't exist. You need to create a default profile (type 'conan profile detect' command) or specify your own profile with '--profile:build=<myprofile>'
Typically you just want to create the default build profile using
conan profile detect
detect means to detect the compiler.
The following list of templates is predefined for conan 2.0.6:
You can check for yourself using
conan new --help
In the output from this command, look for positional arguments -> template. In the help text, you’ll find a list of possible templates.
You want to initialize your conan project using a command such as
conan new cmake_exe
but you see the following error message:
ERROR: Missing definitions for the template. Required definitions are: 'name', 'version'
Conan wants you to specify the name and version of your package using -d name=myproject -d version=1.0.0.
Full example:
conan new cmake_exe -d name=MyPkg -d version=1.0.0
You want to initialize a conan project using a command such as
conan new myproject/1.0.0
However, once you run it, you see an error message like
ERROR: Template doesn't exist or not a folder: myproject/1.0.0
The way you have to use conan new changed with Conan version 2.0.
Now you don’t specify the project name but a template! Templates are names such as cmake_exe but the easiest template to start with is basic as it doesn’t require any parameters:
conan new basic
You can also initialize it using a predefined template such as cmake_exe:
conan new cmake_exe -d name=MyProject -d version=1.0.0
The simplest way of starting is by running the following command in your project directory:
conan new basic
This will create conanfile.py from the basic template.
Alternatively, you can initialize it from a predefined template such as cmake_exe:
conan new cmake_exe -d name=myproject -d version=1.0.0
This is the .gitignore I use for most of my conan-built executable projects:
CMakeCache.txt CMakeFiles/ Makefile bin/ cmake_install.cmake conan.lock conanbuildinfo.cmake conanbuildinfo.txt conaninfo.txt graph_info.json
It is debatable whether you should include lock files such as conan.lock. My opinion is that in the development phase they should be ignored but reconsidered when entering into production service.
Important note: This post is for Conan 1.x and is not compatible with the current version conan 2.x! See How to initialize C++ project using conan 2.x for an updated version of this post!
In the directory where you want to create the project, run (obviously, replace mypackageby the name of everywhere in our code!)
conan new mypackage/1.0.0 -s
-s is important here. It tells conan that the source is available in the project directory and it should not be pulled using git etc.
This will initialize a shared library project, which we will now modify to build an executable.
First, open src/CMakeLists.txt and change add_library() to add_executable(), for example
add_library(mypackage mypackage.cpp)
to
add_executable(mypackage mypackage.cpp)
Now we shall modify conanfile.py to properly build & install the executable:
def package(self):
self.copy("*.h", dst="include", src="src")
self.copy("*.lib", dst="lib", keep_path=False)
self.copy("*.dll", dst="bin", keep_path=False)
self.copy("*.dylib*", dst="lib", keep_path=False)
self.copy("*.so", dst="lib", keep_path=False)
self.copy("*.a", dst="lib", keep_path=False)
def package_info(self):
self.cpp_info.libs = ["NoxecoDB"]
with
def package(self):
self.copy("mypackage", src="bin", dst="bin", keep_path=False)
def package_info(self):
self.env_info.PATH = os.path.join(self.package_folder, "bin")
def deploy(self):
self.copy("mypackage", dst="bin", src="bin")
and add
import os.path
to the top of the file
Now let’s add a main() function to src/mypackage.cpp. Replace the file’s content with
#include <iostream>
int main(int argc, char** argv) {
std::cout << "Hello World!" <<std::endl;
}
Now it’s time to install the dependencies & build the project using
conan install . && conan build .
The executable will be in
bin/mypackage
You can run it using
./bin/mypackage
which will print
Hello World!
I also recommend to add this .gitignore:
CMakeCache.txt CMakeFiles/ Makefile bin/ cmake_install.cmake conan.lock conanbuildinfo.cmake conanbuildinfo.txt conaninfo.txt graph_info.json
When running
conan install .
you see ERROR: Missing binary error messages like this:
Installing (downloading, building) binaries... ERROR: Missing binary: cpr/1.6.2:76fe60a9d5c829a2384b0f578695b5a6357b8acc ERROR: Missing binary: gtest/cci.20210126:c37dc23725d84483088a68c29e2dd7122c328359 ERROR: Missing binary: jsoncpp/1.9.4:718278bac9f92b77a9a44bfbe1aa00d1c8344d51 ERROR: Missing binary: libcurl/7.78.0:d287dc966931230205222ceabf47400733e72fa3 ERROR: Missing binary: openssl/1.1.1l:c3baf9fae083edda2e0c5ef3337b6a111016a898 ERROR: Missing binary: zlib/1.2.11:c3baf9fae083edda2e0c5ef3337b6a111016a898
Use the --build=missing flag for conan install to enable building the dependencies for which no binaries are available:
conan install . --build=missing
Configuration:
[settings]
arch=armv8
arch_build=armv8
build_type=Release
compiler=gcc
compiler.libcxx=libstdc++
compiler.version=9
os=Linux
os_build=Linux
[options]
[build_requires]
[env]
openssl/1.1.1l: Not found in local cache, looking in remotes...
openssl/1.1.1l: Trying with 'conancenter'...
Downloading conanmanifest.txt completed [0.26k]
Downloading conanfile.py completed [40.47k]
Downloading conan_export.tgz completed [0.25k]
Decompressing conan_export.tgz completed [0.00k]
openssl/1.1.1l: Downloaded recipe revision 0
cpr/1.6.2: Not found in local cache, looking in remotes...
cpr/1.6.2: Trying with 'conancenter'...
Downloading conanmanifest.txt completed [0.25k]
Downloading conanfile.py completed [9.62k]
Downloading conan_export.tgz completed [0.30k]
Decompressing conan_export.tgz completed [0.00k]
cpr/1.6.2: Downloaded recipe revision 0
WARN: cpr/1.6.2: requirement libcurl/7.80.0 overridden by elasticlient/0.2 to libcurl/7.78.0
libcurl/7.78.0: Not found in local cache, looking in remotes...
libcurl/7.78.0: Trying with 'conancenter'...
Downloading conanmanifest.txt completed [0.70k]
Downloading conanfile.py completed [27.11k]
Downloading conan_export.tgz completed [0.23k]
Decompressing conan_export.tgz completed [0.00k]
libcurl/7.78.0: Downloaded recipe revision 0
jsoncpp/1.9.4: Not found in local cache, looking in remotes...
jsoncpp/1.9.4: Trying with 'conancenter'...
Downloading conanmanifest.txt completed [0.65k]
Downloading conanfile.py completed [4.90k]
Downloading conan_export.tgz completed [0.25k]
Decompressing conan_export.tgz completed [0.00k]
jsoncpp/1.9.4: Downloaded recipe revision 0
gtest/cci.20210126: Not found in local cache, looking in remotes...
gtest/cci.20210126: Trying with 'conancenter'...
Downloading conanmanifest.txt completed [0.39k]
Downloading conanfile.py completed [8.14k]
Downloading conan_export.tgz completed [0.32k]
Decompressing conan_export.tgz completed [0.00k]
gtest/cci.20210126: Downloaded recipe revision 0
conanfile.py (elasticlient/0.2): Installing package
Requirements
cpr/1.6.2 from 'conancenter' - Downloaded
jsoncpp/1.9.4 from 'conancenter' - Downloaded
libcurl/7.78.0 from 'conancenter' - Downloaded
openssl/1.1.1l from 'conancenter' - Downloaded
zlib/1.2.11 from 'conancenter' - Cache
Packages
cpr/1.6.2:76fe60a9d5c829a2384b0f578695b5a6357b8acc - Missing
jsoncpp/1.9.4:718278bac9f92b77a9a44bfbe1aa00d1c8344d51 - Missing
libcurl/7.78.0:d287dc966931230205222ceabf47400733e72fa3 - Missing
openssl/1.1.1l:c3baf9fae083edda2e0c5ef3337b6a111016a898 - Missing
zlib/1.2.11:c3baf9fae083edda2e0c5ef3337b6a111016a898 - Missing
Build requirements
gtest/cci.20210126 from 'conancenter' - Downloaded
Build requirements packages
gtest/cci.20210126:c37dc23725d84483088a68c29e2dd7122c328359 - Missing
Installing (downloading, building) binaries...
ERROR: Missing binary: cpr/1.6.2:76fe60a9d5c829a2384b0f578695b5a6357b8acc
ERROR: Missing binary: gtest/cci.20210126:c37dc23725d84483088a68c29e2dd7122c328359
ERROR: Missing binary: jsoncpp/1.9.4:718278bac9f92b77a9a44bfbe1aa00d1c8344d51
ERROR: Missing binary: libcurl/7.78.0:d287dc966931230205222ceabf47400733e72fa3
ERROR: Missing binary: openssl/1.1.1l:c3baf9fae083edda2e0c5ef3337b6a111016a898
ERROR: Missing binary: zlib/1.2.11:c3baf9fae083edda2e0c5ef3337b6a111016a898
Run this command to create a debug profile from your default profile:
cp ~/.conan/profiles/default ~/.conan/profiles/debug && sed -i -e 's/Release/Debug/g' ~/.conan/profiles/debug
Example output from conan profile show debug:
[settings] os=Linux os_build=Linux arch=x86_64 arch_build=x86_64 compiler=gcc compiler.version=9 compiler.libcxx=libstdc++ build_type=Debug [options] [conf] [build_requires] [env]
In order to list local conan packages, run
conan search
$ conan search Existing package recipes: cpr/1.6.2 elasticlient/0.2 elasticlient/0.2@demo/testing gtest/cci.20210126 jsoncpp/1.9.4 libcurl/7.69.1 libcurl/7.78.0 openssl/1.1.1l zlib/1.2.11
When building your conan package, you see this CMake error:
CMake Error at /usr/share/cmake-3.16/Modules/FindPackageHandleStandardArgs.cmake:146 (message): Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the system variable OPENSSL_ROOT_DIR (missing: OPENSSL_CRYPTO_LIBRARY OPENSSL_INCLUDE_DIR) Call Stack (most recent call first): /usr/share/cmake-3.16/Modules/FindPackageHandleStandardArgs.cmake:393 (_FPHSA_FAILURE_MESSAGE) /usr/share/cmake-3.16/Modules/FindOpenSSL.cmake:447 (find_package_handle_standard_args) ../_deps/curl-src/CMakeLists.txt:365 (find_package)
even though your conanfile.py declares OpenSSL as a dependency:
class MyPackageConan(ConanFile):
# ...
requires = ("openssl/1.1.1l", )Make sure that the project’s CMakeLists.txt contains these lines:
include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()Typically, the way to do this is to use this code which is automatically generated by conan new:
# This small hack might be useful to guarantee proper /MT /MD linkage
# in MSVC if the packaged project doesn't have variables to set it
# properly
tools.replace_in_file("hello/CMakeLists.txt", "PROJECT(HelloWorld)",
'''PROJECT(HelloWorld)
include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()''')in source() like this:
def source(self):
self.run("git clone https://github.com/conan-io/hello.git")
# This small hack might be useful to guarantee proper /MT /MD linkage
# in MSVC if the packaged project doesn't have variables to set it
# properly
tools.replace_in_file("hello/CMakeLists.txt", "PROJECT(HelloWorld)",
'''PROJECT(HelloWorld)
include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()''')
Note that you need to replace both hello/CMakeLists.txt with the correct filename (typically, just replace hello by). Also, you need to replace both instances PROJECT(HelloWorld) by the actual line from your CMakeLists.txt in order for the replace command to work.
Just add build_requires = ('dep1/version1', 'dep1/version2') to your conanfile.py:
class MyPackageConan(ConanFile):
# ...
requires = ("openssl/1.1.1l", )
build_requires = ("jsoncpp/1.9.4", )
If you want to run git submodule update in your conanfile.py, you can simple add a self.run() command after the git clone command:
self.run("git clone https://github.com/conan-io/hello.git")
self.run("cd hello && git submodule update --init --recursive")
self.run("git clone https://github.com/seznam/elasticlient.git -b version-0.2")
self.run("cd elasticlient && git submodule update --init --recursive")
Note that you need to cd <directory> && git submodule update
If you want to create a new conan build recipe for a package that already exists, use
conan new hello/0.1
conan new hello/0.1 -t
More info: See packaging docs
When building a library using conan, this is the default conanfile.py definition for building using CMake
cmake = CMake(self) cmake.configure(source_folder="hello") cmake.build()
You can easily add definitions like this:
cmake.definitions["MY_FLAG"] = "1"
This will generate -DMY_FLAG=1 when calling CMake
Full example:
cmake = CMake(self) cmake.definitions["USE_SYSTEM_CPR"] = "1 cmake.configure(source_folder="elasticlient")" cmake.build()
Note that you need to add all cmake.definitions calls before calling cmake.configure()