Write (some of the) command line options to a configuration file.

This allows to later review how the command was run, and more importantly
editing the configuration file (via new commands, not implemented yet) and
signal the already running pgcopydb to dynamically apply new settings.

Author: dimitri

src/bin/pgcopydb/cli_common.c

@@ -17,6 +17,7 @@
 #include "cli_common.h"
 #include "cli_root.h"
 #include "commandline.h"
+#include "config.h"
 #include "copydb.h"
 #include "env_utils.h"
 #include "file_utils.h"
@@ -1155,6 +1156,16 @@ cli_copy_prepare_specs(CopyDataSpec *copySpecs, CopyDataSection section)
 		exit(EXIT_CODE_INTERNAL_ERROR);
 	}
 
+	strlcpy(copyDBoptions.dir, copySpecs->cfPaths.topdir, MAXPGPATH);
+
+	(void) config_init(&copyDBoptions);
+
+	if (!config_write_file(&copyDBoptions, copySpecs->cfPaths.conffile))
+	{
+		/* errors have already been logged */
+		exit(EXIT_CODE_INTERNAL_ERROR);
+	}
+
 	if (!copydb_init_specs(copySpecs, &copyDBoptions, section))
 	{
 		/* errors have already been logged */

src/bin/pgcopydb/config.c

@@ -0,0 +1,223 @@
+/*
+ * src/bin/pgcopydb/config.c
+ *     Configuration functions for pgcopydb.
+ *
+ * Licensed under the PostgreSQL License.
+ *
+ */
+
+#include <inttypes.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+#include "config.h"
+#include "defaults.h"
+#include "ini_file.h"
+#include "log.h"
+#include "parsing_utils.h"
+
+#define OPTION_PGCOPYDB_DIR(config) \
+	make_strbuf_option("pgcopydb", "dir", "dir", true, MAXCONNINFO, \
+					   config->dir)
+
+#define OPTION_PGCOPYDB_SOURCE(config) \
+	make_strbuf_option("pgcopydb", "source", "source", true, MAXCONNINFO, \
+					   config->source_pguri)
+
+#define OPTION_PGCOPYDB_TARGET(config) \
+	make_strbuf_option("pgcopydb", "target", "source", true, MAXCONNINFO, \
+					   config->target_pguri)
+
+#define OPTION_PGCOPYDB_TABLE_JOBS(config) \
+	make_int_option_default("pgcopydb", "table-jobs", "table-jobs", \
+							true, &(config->tableJobs), \
+							DEFAULT_TABLE_JOBS)
+
+#define OPTION_PGCOPYDB_INDEX_JOBS(config) \
+	make_int_option_default("pgcopydb", "index-jobs", "index-jobs", \
+							true, &(config->indexJobs), \
+							DEFAULT_INDEX_JOBS)
+
+#define SET_INI_OPTIONS_ARRAY(config) \
+	{ \
+		OPTION_PGCOPYDB_DIR(config), \
+		OPTION_PGCOPYDB_SOURCE(config), \
+		OPTION_PGCOPYDB_TARGET(config), \
+		OPTION_PGCOPYDB_TABLE_JOBS(config), \
+		OPTION_PGCOPYDB_INDEX_JOBS(config), \
+		INI_OPTION_LAST \
+	}
+
+
+/*
+ * config_init initializes a CopyDBOptions with the default values.
+ */
+void
+config_init(CopyDBOptions *config)
+{
+	IniOption options[] = SET_INI_OPTIONS_ARRAY(config);
+
+	log_trace("config_init");
+
+	if (!ini_validate_options(options))
+	{
+		log_error("Please review your setup options per above messages");
+		exit(EXIT_CODE_BAD_CONFIG);
+	}
+}
+
+
+/*
+ * config_read_file overrides values in given CopyDBOptions with whatever
+ * values are read from given configuration filename.
+ */
+bool
+config_read_file(CopyDBOptions *config, const char *filename)
+{
+	IniOption options[] = SET_INI_OPTIONS_ARRAY(config);
+
+	log_debug("Reading configuration from %s", filename);
+
+	if (!read_ini_file(filename, options))
+	{
+		log_error("Failed to parse configuration file \"%s\"", filename);
+		return false;
+	}
+
+	return true;
+}
+
+
+/*
+ * config_write_file writes the current values in given CopyDBOptions to
+ * filename.
+ */
+bool
+config_write_file(CopyDBOptions *config, const char *filename)
+{
+	log_trace("config_write_file \"%s\"", filename);
+
+	FILE *fileStream = fopen_with_umask(filename, "w", FOPEN_FLAGS_W, 0644);
+	if (fileStream == NULL)
+	{
+		/* errors have already been logged */
+		return false;
+	}
+
+	bool success = config_write(fileStream, config);
+
+	if (fclose(fileStream) == EOF)
+	{
+		log_error("Failed to write file \"%s\"", filename);
+		return false;
+	}
+
+	return success;
+}
+
+
+/*
+ * config_write write the current config to given STREAM.
+ */
+bool
+config_write(FILE *stream, CopyDBOptions *config)
+{
+	IniOption options[] = SET_INI_OPTIONS_ARRAY(config);
+
+	return write_ini_to_stream(stream, options);
+}
+
+
+/*
+ * config_to_json populates given jsRoot object with the INI configuration
+ * sections as JSON objects, and the options as keys to those objects.
+ */
+bool
+config_to_json(CopyDBOptions *config, JSON_Value *js)
+{
+	JSON_Object *jsRoot = json_value_get_object(js);
+	IniOption options[] = SET_INI_OPTIONS_ARRAY(config);
+
+	return ini_to_json(jsRoot, options);
+}
+
+
+/*
+ * config_log_settings outputs a DEBUG line per each config parameter in the
+ * given CopyDBOptions.
+ */
+void
+config_log_settings(CopyDBOptions *config)
+{
+	log_debug("pgcopydb.dir: %s", config->dir);
+	log_debug("pgcopydb.source_pguri: %s", config->source_pguri);
+	log_debug("pgcopydb.target_pguri: %s", config->target_pguri);
+
+	log_debug("pgcopydb.table-jobs: %d", config->tableJobs);
+	log_debug("pgcopydb.index-jobs: %d", config->indexJobs);
+}
+
+
+/*
+ * config_get_setting returns the current value of the given option "path"
+ * (thats a section.option string). The value is returned in the pre-allocated
+ * value buffer of size size.
+ */
+bool
+config_get_setting(CopyDBOptions *config,
+				   const char *filename,
+				   const char *path,
+				   char *value, size_t size)
+{
+	IniOption options[] = SET_INI_OPTIONS_ARRAY(config);
+
+	return ini_get_setting(filename, options, path, value, size);
+}
+
+
+/*
+ * config_set_setting sets the setting identified by "path" (section.option) to
+ * the given value. The value is passed in as a string, which is going to be
+ * parsed if necessary.
+ */
+bool
+config_set_setting(CopyDBOptions *config,
+				   const char *filename,
+				   const char *path,
+				   char *value)
+{
+	IniOption options[] = SET_INI_OPTIONS_ARRAY(config);
+
+	log_trace("config_set_setting: %s = %s", path, value);
+
+	if (!ini_set_setting(filename, options, path, value))
+	{
+		/* errors have already been logged */
+		return false;
+	}
+
+	return true;
+}
+
+
+/*
+ * config_merge_options merges any option setup in options into config. Its
+ * main use is to override configuration file settings with command line
+ * options.
+ */
+bool
+config_merge_options(CopyDBOptions *config, CopyDBOptions *options,
+					 const char *filename)
+{
+	IniOption configOptions[] = SET_INI_OPTIONS_ARRAY(config);
+	IniOption optionsOptions[] = SET_INI_OPTIONS_ARRAY(options);
+
+	log_trace("config_merge_options");
+
+	if (ini_merge(configOptions, optionsOptions))
+	{
+		return config_write_file(config, filename);
+	}
+
+	return false;
+}

src/bin/pgcopydb/config.h

@@ -0,0 +1,40 @@
+/*
+ * src/bin/pgcopydb/config.h
+ *     Configuration data structure and function definitions
+ *
+ * Licensed under the PostgreSQL License.
+ *
+ */
+
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#include <limits.h>
+#include <stdbool.h>
+
+#include "cli_common.h"
+#include "config.h"
+#include "defaults.h"
+
+
+void config_init(CopyDBOptions *config);
+bool config_read_file(CopyDBOptions *config, const char *filename);
+bool config_write_file(CopyDBOptions *config, const char *filename);
+bool config_write(FILE *stream, CopyDBOptions *config);
+bool config_to_json(CopyDBOptions *config, JSON_Value *js);
+void config_log_settings(CopyDBOptions *config);
+
+bool config_get_setting(CopyDBOptions *config,
+						const char *filename,
+						const char *path,
+						char *value, size_t size);
+
+bool config_set_setting(CopyDBOptions *config,
+						const char *filename,
+						const char *path,
+						char *value);
+
+bool config_merge_options(CopyDBOptions *config, CopyDBOptions *options,
+						  const char *filename);
+
+#endif /* CONFIG_H */

src/bin/pgcopydb/copydb.c

@@ -438,6 +438,9 @@ copydb_prepare_filepaths(CopyFilePaths *cfPaths,
 	/* first copy the top directory */
 	strlcpy(cfPaths->topdir, topdir, sizeof(cfPaths->topdir));
 
+	/* prepare the path to the config.ini file */
+	sformat(cfPaths->conffile, MAXPGPATH, "%s/config.ini", cfPaths->topdir);
+
 	/* some processes use an additional per-service pidfile */
 	if (serviceName != NULL)
 	{

src/bin/pgcopydb/copydb_paths.h

@@ -59,6 +59,7 @@ typedef struct CDCPaths
 typedef struct CopyFilePaths
 {
 	char topdir[MAXPGPATH];           /* /tmp/pgcopydb */
+	char conffile[MAXPGPATH];         /* /tmp/pgcopydb/config.ini */
 	char pidfile[MAXPGPATH];          /* /tmp/pgcopydb/pgcopydb.pid */
 	char spidfile[MAXPGPATH];         /* /tmp/pgcopydb/pgcopydb.service.pid */
 	char snfile[MAXPGPATH];           /* /tmp/pgcopydb/snapshot */