util/http: lazily init the global HTTP client
GetGlobalHttpClient returned a nil client until InitGlobalHttpClient ran,
which only happens in weed.go's main. Anything that starts a command
in-process bypasses that: the admin server's metrics goroutine seeds a
dashboard sample on startup, reaching fetchPublicUrlMap -> GetGlobalHttpClient().Do,
and nil-derefs the receiver in GetHttpScheme.
Init the client on first Get via sync.Once so it is never nil regardless of
the startup path. InitGlobalHttpClient keeps its eager-init role through the
same Once.
* Added global http client
* Added Do func for global http client
* Changed the code to use the global http client
* Fix http client in volume uploader
* Fixed pkg name
* Fixed http util funcs
* Fixed http client for bench_filer_upload
* Fixed http client for stress_filer_upload
* Fixed http client for filer_server_handlers_proxy
* Fixed http client for command_fs_merge_volumes
* Fixed http client for command_fs_merge_volumes and command_volume_fsck
* Fixed http client for s3api_server
* Added init global client for main funcs
* Rename global_client to client
* Changed:
- fixed NewHttpClient;
- added CheckIsHttpsClientEnabled func
- updated security.toml in scaffold
* Reduce the visibility of some functions in the util/http/client pkg
* Added the loadSecurityConfig function
* Use util.LoadSecurityConfiguration() in NewHttpClient func
Chris Lu