Environment variables

Apart from Block Rules, fltr is configured entirely through environment variables.

Setting environment variables

To set variables temporarily, use export <VAR_NAME>=<VALUE>. Add the same command to your ~/.bashrc or the equivalent configuration file for your shell, to set them permanently.

Alternatively, prepend the environment variables to each fltr command like this <VAR_NAME>=<VALUE> fltr.

Upstreams

FLTR_ALLOW_UPSTREAM

URL for requests that do not match any Block Rules. This is the only required variable.

FLTR_BLOCK_UPSTREAM

URL for requests that match any Block Rules. Without one, blocked requests are discarded. See How it works for the full request flow.

Block Rules

FLTR_BLOCK_RULES_FILE

Path to the JSON Block Rules file. Defaults to block_rules.json in the current directory. See Block Rules for the file format.

FLTR_CASE_SENSITIVE

Enable case-sensitive Block Rule matching. By default both the Searchable Content and the terms are lowercased before matching; set this to true to match case-sensitively. Invalid values fall back to case-insensitive matching.

Request limits

FLTR_MAX_BODY_SIZE

Maximum request body size, using decimal units (e.g., 5 MB = 5,000,000 bytes, 1 GB, 512 KB) or a bare byte count. A request whose body exceeds this is rejected with 413 request too large; see HTTP behavior.

Server

FLTR_ADDR

Address where the proxy listens.

Logging

LOG_LEVEL

Log level: a valid logrus Level, for example debug, info, or warning. Invalid values fall back to info.

LOG_FORMAT

Log format: text (written to stderr) or json (written to stdout). Invalid values fall back to text.