Merge branch 'marc/52-start-stop-scripts' into 'master'

## [Unreleased]

### New

- Added a new script for starting and stopping daemons on multiple

  nodes ([!135](https://storage.bsc.es/gitlab/hpc/gekkofs/-/merge_requests/135)).

- Added statistics gathering on daemons ([!132](https://storage.bsc.es/gitlab/hpc/gekkofs/-/merge_requests/132)).

    - Stats output can be enabled with:

    - `--enable-collection` collects normal statistics.

    - `--enable-chunkstats` collects extended chunk statistics.

- Statistics output to file is controlled by `--output-stats <filename>`

- Added Prometheus support for outputting

  statistics ([!132](https://storage.bsc.es/gitlab/hpc/gekkofs/-/merge_requests/132)):

- Added Prometheus support for outputting statistics ([!132](https://storage.bsc.es/gitlab/hpc/gekkofs/-/merge_requests/132)):

    - Prometheus dependency optional and enabled at compile time with the CMake argument `GKFS_ENABLE_PROMETHEUS`.

    - `--enable-prometheus` enables statistics pushing to Prometheus if statistics are enabled.

    - `--prometheus-gateway` sets an IP and port for the Prometheus connection.

- `-c` argument has been moved to `--clean-rootdir-finish` and is now used to clean rootdir/metadir on daemon

  shutdown ([!110](https://storage.bsc.es/gitlab/hpc/gekkofs/-/merge_requests/110)).

- Environment variable to change Daemon log levels was changed from `GKFS_LOG_LEVEL`

  to `GKFS_DAEMON_LOG_LEVEL` ([!135](https://storage.bsc.es/gitlab/hpc/gekkofs/-/merge_requests/135)).

### Removed

- Removed old initialization code in the GekkoFS

For MPI application, the `LD_PRELOAD` variable can be passed with the `-x` argument for `mpirun/mpiexec`.

## Run GekkoFS daemons on multiple nodes (beta version!)

The `scripts/run/gkfs` script can be used to simplify starting the GekkoFS daemon on one or multiple nodes. To start

GekkoFS on multiple nodes, a Slurm environment that can execute `srun` is required. Users can further

modify `scripts/run/gkfs.conf` to mold default configurations to their environment.

The following options are available for `scripts/run/gkfs`:

```bash

usage: gkfs [-h/--help] [-r/--rootdir <path>] [-m/--mountdir <path>] [-a/--args <daemon_args>] [-f/--foreground <false>]

        [--srun <false>] [-n/--numnodes <jobsize>] [--cpuspertask <64>] [--numactl <false>] [-v/--verbose <false>]

        {start,stop}

    This script simplifies the starting and stopping GekkoFS daemons. If daemons are started on multiple nodes,

    a Slurm environment is required. The script looks for the 'gkfs.conf' file in the same directory where

    additional permanent configurations can be set.

    positional arguments:

            command                 Command to execute: 'start' and 'stop'

    optional arguments:

            -h, --help              Shows this help message and exits

            -r, --rootdir <path>    Providing the rootdir path for GekkoFS daemons.

            -m, --mountdir <path>   Providing the mountdir path for GekkoFS daemons.

            -a, --args <daemon_arguments>

                                    Add various additional daemon arguments, e.g., "-l ib0 -P ofi+psm2".

            -f, --foreground        Starts the script in the foreground. Daemons are stopped by pressing 'q'.

            --srun                  Use srun to start daemons on multiple nodes.

            -n, --numnodes <n>      GekkoFS daemons are started on n nodes.

                                    Nodelist is extracted from Slurm via the SLURM_JOB_ID env variable.

            --cpuspertask <#cores>  Set the number of cores the daemons can use. Must use '--srun'.

            --numactl               Use numactl for the daemon. Modify gkfs.conf for further numactl configurations.

            -c, --config            Path to configuration file. By defaults looks for a 'gkfs.conf' in this directory.

            -v, --verbose           Increase verbosity

```

### Logging

The following environment variables can be used to enable logging in the client

library: `LIBGKFS_LOG=<module>` and `LIBGKFS_LOG_OUTPUT=<path/to/file>` to

configure the output module and set the path to the log file of the client

library. If not path is specified in `LIBGKFS_LOG_OUTPUT`, the client library

will send log messages to `/tmp/gkfs_client.log`.

The following environment variables can be used to enable logging in the client library: `LIBGKFS_LOG=<module>`

and `LIBGKFS_LOG_OUTPUT=<path/to/file>` to configure the output module and set the path to the log file of the client

library. If not path is specified in `LIBGKFS_LOG_OUTPUT`, the client library will send log messages

to `/tmp/gkfs_client.log`.

The following modules are available:

setting it to `LIBGKFS_LOG_SYSCALL_FILTER=epoll_wait,epoll_create` will filter

out any log entries from the `epoll_wait()` and `epoll_create()` system calls.

Additionally, setting the `LIBGKFS_LOG_OUTPUT_TRUNC` environment variable with

a value different from `0` will instruct the logging subsystem to truncate

the file used for logging, rather than append to it.

Additionally, setting the `LIBGKFS_LOG_OUTPUT_TRUNC` environment variable with a value different from `0` will instruct

the logging subsystem to truncate the file used for logging, rather than append to it.

For the daemon, the `GKFS_DAEMON_LOG_PATH=<path/to/file>` environment variable

can be provided to set the path to the log file, and the log module can be

selected with the `GKFS_LOG_LEVEL={off,critical,err,warn,info,debug,trace}`

For the daemon, the `GKFS_DAEMON_LOG_PATH=<path/to/file>` environment variable can be provided to set the path to the

log file, and the log module can be selected with the `GKFS_DAEMON_LOG_LEVEL={off,critical,err,warn,info,debug,trace}`

environment variable.

# Miscellaneous

For MPI applications, the `LD_PRELOAD` and `LIBGKFS_HOSTS_FILE` variables can be passed with the `-x` argument

for `mpirun/mpiexec`.

## Run GekkoFS daemons on multiple nodes (beta version!)

The `scripts/run/gkfs` script can be used to simplify starting the GekkoFS daemon on one or multiple nodes. To start

GekkoFS on multiple nodes, a Slurm environment that can execute `srun` is required. Users can further

modify `scripts/run/gkfs.conf` to mold default configurations to their environment.

The following options are available for `scripts/run/gkfs`:

```bash

usage: gkfs [-h/--help] [-r/--rootdir <path>] [-m/--mountdir <path>] [-a/--args <daemon_args>] [-f/--foreground <false>]

        [--srun <false>] [-n/--numnodes <jobsize>] [--cpuspertask <64>] [--numactl <false>] [-v/--verbose <false>]

        {start,stop}

    This script simplifies the starting and stopping GekkoFS daemons. If daemons are started on multiple nodes,

    a Slurm environment is required. The script looks for the 'gkfs.conf' file in the same directory where

    additional permanent configurations can be set.

    positional arguments:

            command                 Command to execute: 'start' and 'stop'

    optional arguments:

            -h, --help              Shows this help message and exits

            -r, --rootdir <path>    Providing the rootdir path for GekkoFS daemons.

            -m, --mountdir <path>   Providing the mountdir path for GekkoFS daemons.

            -a, --args <daemon_arguments>

                                    Add various additional daemon arguments, e.g., "-l ib0 -P ofi+psm2".

            -f, --foreground        Starts the script in the foreground. Daemons are stopped by pressing 'q'.

            --srun                  Use srun to start daemons on multiple nodes.

            -n, --numnodes <n>      GekkoFS daemons are started on n nodes.

                                    Nodelist is extracted from Slurm via the SLURM_JOB_ID env variable.

            --cpuspertask <#cores>  Set the number of cores the daemons can use. Must use '--srun'.

            --numactl               Use numactl for the daemon. Modify gkfs.conf for further numactl configurations.

            -c, --config            Path to configuration file. By defaults looks for a 'gkfs.conf' in this directory.

            -v, --verbose           Increase verbosity

```

### Logging

#### Client logging

#### Daemon logging

For the daemon, the `GKFS_DAEMON_LOG_PATH=<path/to/file>` environment variable can be provided to set the path to the

log file, and the log module can be selected with the `GKFS_LOG_LEVEL={off,critical,err,warn,info,debug,trace}`

log file, and the log module can be selected with the `GKFS_DAEMON_LOG_LEVEL={off,critical,err,warn,info,debug,trace}`

environment variable whereas `trace` produces the most trace records while `info` is the default value.

 No newline at end of file

// environment prefixes (are concatenated in env module at compile time)

#define CLIENT_ENV_PREFIX "LIBGKFS_"

#define DAEMON_ENV_PREFIX "GKFS_"

#define DAEMON_ENV_PREFIX "GKFS_DAEMON_"

#define COMMON_ENV_PREFIX "GKFS_"

namespace gkfs::config {

#include <config.hpp>

#define ADD_PREFIX(str) DAEMON_ENV_PREFIX str

#define ADD_PREFIX(str) COMMON_ENV_PREFIX str

/* Environment variables for the GekkoFS daemon */

namespace gkfs::env {