Inline bash scripts in Nix

[steve-chavez]

Problem

There are various cases where bash scripts are source from within Nix and then they have their variables replaced with substitute:

• postgres/flake.nix

  Lines 498 to 510 in 61ff753

  	pkgs.runCommand "start-postgres-client" { } ''
  	mkdir -p $out/bin
  	substitute ${./nix/tools/run-client.sh.in} $out/bin/start-postgres-client \
  	--subst-var-by 'PGSQL_DEFAULT_PORT' '${pgsqlDefaultPort}' \
  	--subst-var-by 'PGSQL_SUPERUSER' '${pgsqlSuperuser}' \
  	--subst-var-by 'PSQL15_BINDIR' '${basePackages.psql_15.bin}' \
  	--subst-var-by 'PSQL17_BINDIR' '${basePackages.psql_17.bin}' \
  	--subst-var-by 'PSQLORIOLEDB17_BINDIR' '${basePackages.psql_orioledb-17.bin}' \
  	--subst-var-by 'MIGRATIONS_DIR' '${migrationsDir}' \
  	--subst-var-by 'POSTGRESQL_SCHEMA_SQL' '${postgresqlSchemaSql}' \
  	--subst-var-by 'PGBOUNCER_AUTH_SCHEMA_SQL' '${pgbouncerAuthSchemaSql}' \
  	--subst-var-by 'STAT_EXTENSION_SQL' '${statExtensionSql}'
  	chmod +x $out/bin/start-postgres-client

• postgres/flake.nix

  Lines 523 to 528 in 61ff753

  	substitute ${./nix/tools/migrate-tool.sh.in} $out/bin/migrate-postgres \
  	--subst-var-by 'PSQL15_BINDIR' '${basePackages.psql_15.bin}' \
  	--subst-var-by 'PSQL_CONF_FILE' '${configFile}' \
  	--subst-var-by 'PGSODIUM_GETKEY' '${getkeyScript}' \
  	--subst-var-by 'PRIMING_SCRIPT' '${primingScript}' \
  	--subst-var-by 'MIGRATION_DATA' '${migrationData}'

• postgres/flake.nix

  Lines 535 to 537 in 61ff753

  	substitute ${./nix/tools/run-replica.sh.in} $out/bin/start-postgres-replica \
  	--subst-var-by 'PGSQL_SUPERUSER' '${pgsqlSuperuser}' \
  	--subst-var-by 'PSQL15_BINDIR' '${basePackages.psql_15.bin}'

This hurts reusability of the scripts logic and adds verboseness to the scripts.

Solution

Inline the scripts in the Nix file to avoid substitutions.

[samrose]

#1564 (comment)