# fblog
A small tool to view json log files.
## Print specific fields
``` shell-script
fblog -a message -a "status > a" sample_nested.json.log
```
## Prefix Logs
If your query docker or kubectl for multiple pods it will prefix the log
lines: `PODNAME | {"message": "test"}`. `fblog` can parse this and add
it to the message. Just use `-p`.
## Filter
To filter log messages it is possible to use lua. If you are unsure
which variables are available you can use `--print-lua` to see the code
generated by fblog.
```bash
fblog -f 'level ~= "info"' # will print all message where the level is not info
fblog -f 'process == "play"' # will print all message where the process is play
fblog -f 'string.find(fu, "bow.*") ~= nil' # will print all messages where fu starts with bow
fblog -f 'process == "play"' # will print all message where the process is play
fblog -f 'process == "rust" and fu == "bower"'
fblog --no-implicit-filter-return-statement -f 'if 3 > 2 then return true else return false end'
# not valid lua identifiers like log.level gets converted to log_level.
# Every character that is not _ or a letter will be converted to _
fblog -d -f 'log_level == "WARN"' sample_elastic.log
# nested fields are converted to lua records
fblog -d -f 'status.a == 100' sample_nested.json.log
# array fields are converted to lua tables (index starts with 1)
fblog -d -f 'status.d[2] == "a"' sample_nested.json.log
```
## Customize
`fblog` tries to detect the message, severity and timestamp of a log
entry. This behavior can be customized. See `--help` for more
information.
You can customize fblog messages: Format output:
``` shell-script
fblog -p --main-line-format "{{#if short_message}}{{ red short_message }}{{/if}}" sample.json.log
```
The following sanitized variables are provided by fblog:
- fblog_timestamp
- fblog_level
- fblog_message
- fblog_prefix
For the default formatting see `--help`
Nested values are registered as objects. So you can use `nested.value`
to access nested values.
handlebar helpers:
- bold
- yellow
- red
- blue
- purple
- green
- color_rgb 0 0 0
- uppercase
- level_style
- fixed_size 10
## NO_COLOR
`fblog` disables color output if the `NO_COLOR` environment variable is
present.
[no-color](https://no-color.org/)
## Message placeholder substitution
Placeholders in the message (`fblog_message`) can be substituted with
their corresponding values in a context object or array. To enable
substitutions, pass the `-s` flag or either set context key
(`-c context`) or placeholder format (`-F {key}`).
Note that the placeholder format should be written like
`<PREFIX>key<SUFFIX>`, where it would match a placeholder with the key
`key`.
### Example
Given the following log (referred to as `example.log`):
``` json
{"message": "Found #{count} new items.", "extra_data": {"count": 556}, "level": "info"}
```
Running with the following arguments:
``` bash
fblog -c extra_data -F '#{key}' example.log
```
Result:
## Installation
``` bash
cargo install fblog
```
Available in package managers:
[AUR](https://aur.archlinux.org/packages/fblog/),
[brew](https://formulae.brew.sh/formula/fblog)
## Log tailing
`fblog` does not support native log tailing but this is easily
achiveable.
``` bash
Or with kubernetes tooling for example
``` bash
In general you can pipe any endless stream to fblog.
