Loki Log Stream and Filter Expressions

Log Stream Selector

Loki log stream selectors define which log streams to include in your query. Here are some examples:

{job="varlogs"}

{job="varlogs", host="nginx01"}

{job=~"nginx*", host="nginx01"}

{job="varlogs", host="nginx01", filename="/var/log/syslog"}

Each line filter expression has a filter operator followed by text or a regular expression. These filter operators are supported:

Operator	Description
`	=`
`!=`	Log line does not contain string
`	~`
`!~`	Log line does not contain a match to a regex

Include log lines containing "error":

{job="varlogs", host="nginx01"} |= "error"

Exclude log lines containing "info":

{job="varlogs", host="nginx01"} != "info"

Include log lines matching warn or error using regex:
```
{job=~"nginx*", host="nginx01"} |~ "warn|error"
```

Advanced example with JSON parsing and custom line formatting:

{job=~"nginx*", host="nginx01"} |~ "warn|error" | json | line_format " {{.detected_level}} {{.remote_addr}} {{.status}}"