This commit introduced the basic URI rewrite. It allows users to change request URI. Note the "rewrite" option ignores the contained query if any and the query from the request is preserverd.
An example:
"routes": [
    {
        "match": {
            "uri": "/v1/test"
        },
        "action": {
            "return": 200
        }
    },
    {
        "action": {
            "rewrite": "/v1$uri",
            "pass": "routes"
        }
    }
]

Reviewed-by: Alejandro Colomar <alx@nginx.com>

This removes a bunch of unused files that would have been touched by
subsequent commits that switch to using nxt_bool_t (AKA unit6_t) in
structures.

In auto/sources we have

  NXT_LIB_SRC0=" \
      src/nxt_buf_filter.c \
      src/nxt_job_file.c \
      src/nxt_stream_module.c \
      src/nxt_stream_source.c \
      src/nxt_upstream_source.c \
      src/nxt_http_source.c \
      src/nxt_fastcgi_source.c \
      src/nxt_fastcgi_record_parse.c \
  \
      src/nxt_mem_pool_cleanup.h \
      src/nxt_mem_pool_cleanup.c \
  "

None of these seem to actually be used anywhere (other than within
themselves). That variable is _not_ referenced anywhere else.

Also remove the unused related header files: src/nxt_buf_filter.h,
src/nxt_fastcgi_source.h, src/nxt_http_source.h, src/nxt_job_file.h,
src/nxt_stream_source.h and src/nxt_upstream_source.h

Also, these files do not seem to be used, no mention under auto/ or build/

  src/nxt_file_cache.c
  src/nxt_cache.c
  src/nxt_job_file_cache.c

src/nxt_cache.h is #included in src/nxt_main.h, but AFAICT is not
actually used.

With all the above removed

  $ ./configure --openssl --debug --tests && make -j && make -j tests &&
  make libnxt

all builds.

Buildbot passes.

NOTE: You may need to do a 'make clean' before the next build attempt.

Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Due to the need to replace our use of clone/__NR_clone on Linux with
fork(2)/unshare(2) for enabling Linux namespaces(7) to keep the
pthreads(7) API working.  Let's rename NXT_HAVE_CLONE to
NXT_HAVE_LINUX_NS, i.e name it after the feature, not how it's
implemented, then in future if we change how we do namespaces again we
don't have to rename this.

Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

This commit enables the building of the cgroup code. This is only built
when the cgroupv2 filesystem is found.

If cgroupv2 support is found then

  cgroupv2: .................. YES

will be printed by ./configure

Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

It's for the introduction of njs support.
For each option that supports native variable and JS template literals introduced next,
it's unified as template string.

No functional changes.

@alejandro-colomar reported that the build was broken on MacOS

cc  -o build/unitd -pipe -fPIC -fvisibility=hidden -O -W -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -fstrict-aliasing -Wstrict-overflow=5 -Wmissing-prototypes -Werror -g   \
		build/src/nxt_main.o  build/libnxt.a \
		    \
                      \
                    -L/usr/local/Cellar/pcre2/10.40/lib -lpcre2-8
Undefined symbols for architecture x86_64:
  "_nxt_fs_mkdir_parent", referenced from:
      _nxt_runtime_pid_file_create in libnxt.a(nxt_runtime.o)
      _nxt_runtime_controller_socket in libnxt.a(nxt_controller.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [build/unitd] Error 1

This was due to commit 57fc920 ("Socket: Created control socket & pid file
directories.").

This happened because this commit introduced the usage of
nxt_fs_mkdir_parent() in core code which uses nxt_fs_mkdir(), both of
these are defined in src/nxt_fs.c. It turns out however that this file
doesn't get built on MacOS (or any system that isn't Linux or that
lacks a FreeBSD compatible nmount(2) system call) due to the following

In auto/sources we have

  if [ $NXT_HAVE_ROOTFS = YES ]; then
      NXT_LIB_SRCS="$NXT_LIB_SRCS src/nxt_fs.c"
  fi

NXT_HAVE_ROOTFS is set in auto/isolation

  If [ $NXT_HAVE_MOUNT = YES -a $NXT_HAVE_UNMOUNT = YES ]; then
      NXT_HAVE_ROOTFS=YES

      cat << END >> $NXT_AUTO_CONFIG_H
  #ifndef NXT_HAVE_ISOLATION_ROOTFS
  #define NXT_HAVE_ISOLATION_ROOTFS  1
  #endif
  END

  fi

While we do have a check for a generic umount(2) which is found on
MacOS, for mount(2) we currently only check for the Linux mount(2) and
FreeBSD nmount(2) system calls. So NXT_HAVE_ROOTFS is set to NO on MacOS
and we don't build src/nxt_fs.c

This fixes the immediate build issue by taking the mount/umount OS
support out of nxt_fs.c into a new nxt_fs_mount.c file which is guarded
by the above while we now build nxt_fs.c unconditionally.

This should fix the build on any _supported_ system.

Reported-by: Alejandro Colomar <alx@nginx.com>
Fixes: 57fc920 ("Socket: Created control socket & pid file directories.")
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>