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If 'namespace' keyword is used in the backend server settings or/and in the bind string, it means that haproxy process will call setns() to change its default namespace to the configured one and then, it will create a socket in this new namespace. setns() syscall requires CAP_SYS_ADMIN capability in the process Effective set (see man 2 setns). Otherwise, the process must be run as root. To avoid to run haproxy as root, let's add cap_sys_admin capability in the same way as we already added the support for some other network capabilities. As CAP_SYS_ADMIN belongs to CAP_SYS_* capabilities type, let's add a separate flag LSTCHK_SYSADM for it. This flag is set, if the 'namespace' keyword was found during configuration parsing. The flag may be unset only in prepare_caps_for_setuid() or in prepare_caps_from_permitted_set(), which inspect process EUID/RUID and Effective and Permitted capabilities sets. If system doesn't support Linux capabilities or 'cap_sys_admin' was not set in 'setcap', but 'namespace' keyword is presented in the configuration, we keep the previous strict behaviour. Process, that has changed uid to the non-priviledged user, will terminate with alert. This alert invites the user to recheck its configuration. In the case, when haproxy will start and run under a non-root user and 'cap_sys_admin' is not set, but 'namespace' keyword is presented, this patch does not change previous behaviour as well. We'll still let the user to try its configuration, but we inform via warning, that unexpected things, like socket creation errors, may occur.
The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - BRANCHES to understand the project's life cycle and what version to use - LICENSE for the project's license - CONTRIBUTING for the process to follow to submit contributions The more detailed documentation is located into the doc/ directory : - doc/intro.txt for a quick introduction on HAProxy - doc/configuration.txt for the configuration's reference manual - doc/lua.txt for the Lua's reference manual - doc/SPOE.txt for how to use the SPOE engine - doc/network-namespaces.txt for how to use network namespaces under Linux - doc/management.txt for the management guide - doc/regression-testing.txt for how to use the regression testing suite - doc/peers.txt for the peers protocol reference - doc/coding-style.txt for how to adopt HAProxy's coding style - doc/internals for developer-specific documentation (not all up to date)