"Could NOT find CURL (missing: HTTP)" while building on Ubuntu 14

[gholmann16]

"Could NOT find CURL (missing: HTTP)" while building on Ubuntu 14

[TheAssassin]

This is a bug in CMake's FindCURL.cmake on Ubuntu I recently stumbled across, too, and it's not related to AppImageUpdate or its dependency cpr. Please check if curl-config --protocols lists HTTP and HTTPS. If that's the case, then the pkg-config file in /usr/lib/x86_64-linux-gnu/pkgconfig/libcurl.pc (when using amd64, adapt otherwise) is broken. The fix is to add HTTP HTTPS to supported_protocols there:

supported_protocols="DICT FILE FTP FTPS GOPHER GOPHERS HTTP HTTPS IMAP IMAPS LDAP LDAPS MQTT POP3 POP3S RTMP RTSP SCP SFTP SMB SMBS SMTP SMTPS TELNET TFTP"

[TheAssassin]

Also, Ubuntu 14.04 and 14.10 are not supported (there is no Ubuntu 14).

[gholmann16]

What versions are supported then? I'm trying to build on an older version so that people who want to run my program on an older distro can use it.

[TheAssassin]

Ubuntu 14.04 has been end-of-life for more than three years now. Currently, the oldest still-supported Ubuntu LTS release is 18.04. This is also what we use to build AppImageUpdate on. Please note, however, that the deployment process has some complexity, since we need a C++17 compatible compiler. To build an AppImage of AppImageUpdate, use https://github.com/AppImage/AppImageUpdate/blob/main/ci/build-in-docker.sh.

This demonstrates how to set up a compatible compiler to, e.g., build libappimageupdate:

https://github.com/AppImage/AppImageUpdate/blob/af298b7aebfab4bcee7490a86f0471cc22db248b/ci/Dockerfile.x86_64#L28-L32

Note that "not supported" means "no support from the developers", not "it won't work". There are unofficial builds of libappimageupdate on CentOS 7 for instance, they just have to build almost all dependencies themselves.

[probonopd]

Currently, the oldest still-supported Ubuntu LTS release is 18.04.

👍

[TheAssassin]

Closing as wontfix, since the issue is within the Ubuntu-provided libcurl builds. It works fine when building libcurl oneself, or when using the proposed workaround.

[gholmann16]

I did what you said, specifically
sudo sed -i 's|supported_protocols=.*|supported_protocols="DICT FILE FTP FTPS GOPHER GOPHERS HTTP HTTPS IMAP IMAPS LDAP LDAPS MQTT POP3 POP3S RTMP RTSP SCP SFTP SMB SMBS SMTP SMTPS TELNET TFTP"|g' /usr/lib/x86_64-linux-gnu/pkgconfig/libcurl.pc
but it did not do anything. Instead I manually disabled the check but obviously this is not a great solution.

[TheAssassin]

Have you reset your CMake cache properly? Try with a new build directory.

[gholmann16]

Undid my hack and deleted the directory and I still get the same error.
This is how /usr/lib/x86_64-linux-gnu/pkgconfig/libcurl.pc looks:

prefix=/usr
exec_prefix=${prefix}
libdir=${prefix}/lib/x86_64-linux-gnu
includedir=${prefix}/include
supported_protocols="DICT FILE FTP FTPS GOPHER GOPHERS HTTP HTTPS IMAP IMAPS LDAP LDAPS MQTT POP3 POP3S RTMP RTSP SCP SFTP SMB SMBS SMTP SMTPS TELNET TFTP"
supported_features="SSL IPv6 libz AsynchDNS IDN NTLM NTLM_WB TLS-SRP"

Name: libcurl
URL: http://curl.haxx.se/
Description: Library to transfer files with ftp, http, etc.
Version: 7.35.0
Libs: -L${libdir} -lcurl
Libs.private: -lidn -lrtmp -lssl -lcrypto -lssl -lcrypto -Wl,-Bsymbolic-functions -Wl,-z,relro -lgssapi_krb5 -lkrb5 -lk5crypto -lcom_err -llber -llber -lldap -lz
Cflags: -I${includedir} 

[TheAssassin]

Please provide the output of curl-config --protocols.

Note that this is really not AppImageUpdate's fault. If anything, you need to talk to cpr. But even they are not to blame. CMake's doing a bad job here.

Reminds me, please update your CMake version if necessary.

[gholmann16]

I can certainly talk to cpr that's a good idea.
I manually updated cmake to 3.24, is that sufficient?

cmake -version
cmake version 3.24.0-rc2

~/gpgme-1.18.0$  curl-config --protocols
DICT
FILE
FTP
FTPS
GOPHER
HTTP
HTTPS
IMAP
IMAPS
LDAP
LDAPS
POP3
POP3S
RTMP
RTSP
SMTP
SMTPS
TELNET
TFTP

[TheAssassin]

3.24.0 would be latest version of CMake, you're still using a release candidate. But it's good enough.

I don't think cpr can do a lot about it, but you certainly should try. Please mention me there so I get notified and can possibly contribute.