Add support for configuration profiles

CHANGELOG.md

@@ -5,6 +5,10 @@
 ### Added
 
 * The *rollback ratio* is now displayed in the "global" header (#385).
+* Configuration profiles can now be defined at
+  `${XDG_CONFIG_HOME:~/.config}/pg_activity/<profile>.conf` or
+  `/etc/pg_activity/<profile>.conf` as selected from the command line through
+  `--profile <profile>`.
 
 ### Changed
 

README.md

@@ -86,6 +86,11 @@ ex:
 
     pg_activity [options] [connection string]
 
+    Configuration:
+      --profile PROFILE     Configuration profile matching a PROFILE.conf file in
+                            ${XDG_CONFIG_HOME:~/.config}/pg_activity/ or
+                            /etc/pg_activity/.
+
     Options:
       --blocksize BLOCKSIZE
                             Filesystem blocksize (default: 4096).
@@ -140,7 +145,7 @@ ex:
 
 ## Configuration
 
-`pg_activity` may be configured through configuration file, in [INI format][],
+`pg_activity` may be configured through a configuration file, in [INI format][],
 read from `${XDG_CONFIG_HOME:~/.config}/pg_activity.conf` or
 `/etc/pg_activity.conf` in that order. Command-line options may override
 configuration file settings.
@@ -153,6 +158,13 @@ hidden = yes
 width = 9
 ```
 
+Alternatively, the user might define *configuration profiles* in the form of
+files located at `${XDG_CONFIG_HOME:~/.config}/pg_activity/<my-profile>.conf` or
+`/etc/pg_activity/<my-profile>.conf`; these can then be used through the
+`--profile <my-profile>` command-line option. The format of these files is the
+same as the main configuration file.
+
+
 [INI format]: https://docs.python.org/3/library/configparser.html#supported-ini-file-structure
 
 ## Notes

docs/man/pg_activity.1

@@ -347,6 +347,13 @@ required by another session. It shows following information:
 .PD
 .SH "COMMAND-LINE OPTIONS"
 .IX Header "COMMAND-LINE OPTIONS"
+.SS "\s-1CONFIGURATION\s0"
+.IX Subsection "CONFIGURATION"
+.IP "\fB\-\-profile=PROFILE\fR" 2
+.IX Item "--profile=PROFILE"
+.Vb 1
+\&        Configuration profile matching a PROFILE.conf file in ${XDG_CONFIG_HOME:~/.config}/pg_activity/ or /etc/pg_activity/.
+.Ve
 .SS "\s-1OPTIONS\s0"
 .IX Subsection "OPTIONS"
 .IP "\fB\-\-blocksize=BLOCKSIZE\fR" 2

docs/man/pg_activity.pod

@@ -230,6 +230,16 @@ required by another session. It shows following information:
 
 =head1 COMMAND-LINE OPTIONS
 
+=head2 CONFIGURATION
+
+=over 2
+
+=item B<--profile=PROFILE>
+
+	Configuration profile matching a PROFILE.conf file in ${XDG_CONFIG_HOME:~/.config}/pg_activity/ or /etc/pg_activity/.
+
+=back
+
 =head2 OPTIONS
 
 =over 2

pgactivity/cli.py

@@ -59,6 +59,17 @@ def get_parser() -> ArgumentParser:
         add_help=False,
     )
 
+    group = parser.add_argument_group(
+        "Configuration",
+    )
+    group.add_argument(
+        "--profile",
+        help=(
+            "Configuration profile matching a PROFILE.conf file in "
+            "${XDG_CONFIG_HOME:~/.config}/pg_activity/ or /etc/pg_activity/."
+        ),
+    )
+
     group = parser.add_argument_group(
         "Options",
     )
@@ -387,8 +398,8 @@ def main() -> None:
         args.notempfile = True
 
     try:
-        cfg = Configuration.lookup()
-    except ConfigurationError as e:
+        cfg = Configuration.lookup(args.profile)
+    except (ConfigurationError, FileNotFoundError) as e:
         parser.error(str(e))
 
     try:

pgactivity/config.py

@@ -261,14 +261,25 @@ def parse(cls: Type[_T], f: IO[str], name: str) -> _T:
     @classmethod
     def lookup(
         cls: Type[_T],
+        profile: Optional[str],
         *,
         user_config_home: Path = USER_CONFIG_HOME,
         etc: Path = ETC,
     ) -> Optional[_T]:
-        for base in (user_config_home, etc):
-            fpath = base / "pg_activity.conf"
+        if profile is None:
+            for base in (user_config_home, etc):
+                fpath = base / "pg_activity.conf"
+                if fpath.exists():
+                    with fpath.open() as f:
+                        return cls.parse(f, str(fpath))
+            return None
+
+        assert profile  # per argument validation
+        fname = f"{profile}.conf"
+        bases = (user_config_home / "pg_activity", etc / "pg_activity")
+        for base in bases:
+            fpath = base / fname
             if fpath.exists():
                 with fpath.open() as f:
-                    value = cls.parse(f, str(fpath))
-                    return value
-        return None
+                    return cls.parse(f, str(fpath))
+        raise FileNotFoundError(f"profile {profile!r} not found")

tests/test_config.py

@@ -2,6 +2,7 @@
 from typing import Any, Dict
 
 import attr
+import pytest
 
 from pgactivity.config import Configuration, Flag, UISection
 
@@ -78,9 +79,19 @@ def test_lookup(tmp_path: Path) -> None:
     def asdict(cfg: Configuration) -> Dict[str, Any]:
         return {k: attr.asdict(v) for k, v in cfg.items()}
 
-    cfg = Configuration.lookup(user_config_home=tmp_path)
+    cfg = Configuration.lookup(None, user_config_home=tmp_path)
     assert cfg is None
 
     (tmp_path / "pg_activity.conf").write_text("\n".join(["[client]", "width=5"]))
-    cfg = Configuration.lookup(user_config_home=tmp_path)
+    cfg = Configuration.lookup(None, user_config_home=tmp_path)
     assert cfg is not None and asdict(cfg) == {"client": {"hidden": False, "width": 5}}
+
+    (tmp_path / "pg_activity").mkdir()
+    (tmp_path / "pg_activity" / "x.conf").write_text(
+        "\n".join(["[database]", "hidden= on", "width = 3 "])
+    )
+    cfg = Configuration.lookup("x", user_config_home=tmp_path)
+    assert cfg is not None and asdict(cfg) == {"database": {"hidden": True, "width": 3}}
+
+    with pytest.raises(FileNotFoundError):
+        Configuration.lookup("y", user_config_home=tmp_path)