v0.18.0 raw and json formatter improvements, dockerfile, go bump to 1.27.1

doc/sources.md

@@ -32,6 +32,8 @@ type = "file"
 directory         = "/var/log/myapp"
 pattern           = "*.log"
 check_interval_ms = 100
+raw               = false
+from              = "end"
 ```
 
 | Option | Type | Default | Description |
@@ -39,6 +41,8 @@ check_interval_ms = 100
 | `directory` | string | **required** | Directory to scan; not recursive |
 | `pattern` | string | `*` | Glob over filenames; `*` and `?` only |
 | `check_interval_ms` | int | `100` | Directory rescan interval; minimum `10` |
+| `raw` | bool | `false` | Never parse a line: the whole line is the message |
+| `from` | string | `end` | Where a new watcher starts: `end` or `start` of the file |
 
 **Behaviour**
 
@@ -49,15 +53,23 @@ check_interval_ms = 100
   stopped and removed on the next scan.
 - A new watcher seeks to end-of-file. Positions live in memory only, so a
   restart resumes from the current end of each file and content written while
-  LogWisp was down is not read.
+  LogWisp was down is not read. `from = "start"` reads each file whole when its
+  watcher is created instead — what a process writing beside LogWisp needs, at
+  the cost of replaying a file already on disk at every restart.
 - Rotation is detected from size decrease, modification-time reset, a position
   beyond end-of-file, or an inode change. An inode change where the new file is
   already larger than the recorded position is treated as an atomic save, not a
   rotation, and the position is preserved.
-- Lines are parsed as JSON when they contain `time`, `level`, `msg`, and
-  `fields` keys; `time` is read as RFC3339Nano. Anything else is kept as plain
-  text with the level inferred from common markers (`[ERROR]`, `WARN:`, and so
-  on).
+- A line is parsed as JSON only when it is an object whose top-level keys are
+  all drawn from `time`, `level`, `msg` and `fields` — the four an entry can
+  carry. `time` is read as RFC3339Nano. Any other key, and any non-object line,
+  is kept whole as text with the level inferred from common markers
+  (`[ERROR]`, `WARN:`, and so on), because parsing it would drop the rest.
+- `raw = true` skips the JSON branch entirely. The line, plus its newline,
+  becomes the message; `fields` stays empty, the time is the read time, and the
+  level is inferred from the text as for any unparsed line. Paired with
+  `format.type = "raw"` this is byte-exact transport for records LogWisp's
+  envelope cannot hold — see [Formatters](formatters.md#raw).
 - `Source` is set to the file's base name.
 
 **Statistics**: per-watcher size, position, entries read, rotation count, and