node-lookup/AGENTS.md

AGENTS.md

Project Overview

node-lookup is a Go CLI tool that queries a PuppetDB API to retrieve and filter node facts.

Structure

main.go             # entire application source
main_test.go        # unit tests (mock PuppetDB via httptest, no live deps)
go.mod              # Go module (module name: node-lookup)
go.sum              # dependency checksums
Makefile            # build / test / lint / completions / rpm / version-bump targets
packaging/nfpm.yaml # nfpm spec (envsubst-templated) for the RPM
scripts/build-rpm.sh # generates completions + packages the RPM with nfpm
.woodpecker/        # CI: build, test, pre-commit (PR) + release (tag)
dist/               # build output: binary, completions, RPM (not committed)

Build

make build          # -> dist/node-lookup (CGO disabled, static)
# or directly:
go build -o node-lookup ./...

Requires Go 1.21+. Dependencies: github.com/spf13/cobra (CLI), gopkg.in/yaml.v3 (Ansible output).

Packaging (RPM)

make rpm            # build the binary + package it into dist/*.rpm via nfpm

scripts/build-rpm.sh generates bash/zsh/fish completions from the built binary and bundles them alongside /usr/bin/node-lookup. On a v* tag the release pipeline builds the RPM and PUTs it to the artifactapi rpm-internal repo.

Shell completions

Cobra provides a completion subcommand:

node-lookup completion bash   # or zsh / fish / powershell

The RPM installs completions to the standard system paths (/usr/share/bash-completion/completions/, /usr/share/zsh/site-functions/, /usr/share/fish/vendor_completions.d/), so they work automatically once installed. To load ad-hoc in the current shell, e.g. zsh: source <(node-lookup completion zsh).

Running the Tool

./node-lookup --help
./node-lookup -R                          # show all nodes with role fact
./node-lookup -n <hostname>               # lookup a specific node
./node-lookup -F <fact_name>              # filter by fact name
./node-lookup -R -m <value>               # exact value match (-m)
./node-lookup -R -pm <value>              # partial/regex match (-p -m combined)
./node-lookup -R -im <value>              # inverse exact match (-i -m combined)
./node-lookup -R -ipm <value>             # inverse partial match (-i -p -m combined)
./node-lookup -R -p <value>               # value may also be given positionally
./node-lookup -R -1                       # node names only
./node-lookup -R -2                       # values only
./node-lookup -R -C                       # count occurrences
./node-lookup -R -A                       # output as Ansible YAML inventory
./node-lookup -j                          # output as JSON { host → { fact → value } }
./node-lookup --url http://host:8080/...  # override PuppetDB URL for this invocation
echo -e "node1\nnode2" | ./node-lookup -R # pipe node names via stdin

Configuration

Precedence (lowest → highest): defaults < config file < env vars < --url flag

Config file

XDG location: $XDG_CONFIG_HOME/node-lookup/config.yaml (default: ~/.config/node-lookup/config.yaml)

puppetdb_url: http://puppetdbapi.service.consul:8080/pdb/query/v4/facts
role_fact: enc_role

Generate the default config file:

./node-lookup config init

Show the active configuration (after all overrides applied):

./node-lookup config show

Environment variables

Variable	Config key	Description
NODE_LOOKUP_URL	puppetdb_url	PuppetDB facts endpoint
NODE_LOOKUP_ROLE_FACT	role_fact	Fact name used by -R flag

CLI flag

--url <url> overrides the PuppetDB URL for a single invocation (highest precedence).

Code Patterns

• loadConfig(): reads config file → applies env vars → returns config struct. Called once at startup in main().
• buildQuery(): returns a PuppetDB PQL-compatible JSON array string. Uses roleFact from config (not hardcoded). Match modifiers: -p (partial/regex, uses ~ op), -i (inverse, wraps with not), composable.
• Match value / matchValue(): the value to match comes from -m/--match or, if that is empty, an optional positional argument. The positional fallback exists because pflag does not attach a space-separated value to a string flag grouped with a bool flag, so in -pm k8s the k8s arrives as a positional. -m still wins when both are given.
• queryPuppetDB(url, query): takes the URL as a parameter — never reads globals.
• processResults(): iterates facts, returns sorted "certname value" strings. JSON string values are unquoted; other JSON types rendered as compact JSON.
• Output modes: JSON (-j), count (-C), Ansible YAML (-A), node-only (-1), value-only (-2), default (node + value).
• Stdin support: stdinReader() reads node names from stdin only when it is a real pipe/redirect carrying data (and no -n given). Terminals, /dev/null, and empty/closed pipes fall through to a normal query — so running without a TTY (e.g. invoked by an agent or CI) behaves like an interactive run instead of consuming empty input.
• SIGPIPE handling: signal.Ignore(syscall.SIGPIPE) so pipes to head etc. work cleanly.

CLI Framework

Uses Cobra. Root command is the query command. config is a subcommand with init and show sub-subcommands.

Testing

make test           # go test -v -race ./...

main_test.go covers query construction (all -m/-p/-i combinations), value rendering, result processing/counting, config precedence (defaults < file < env), writeDefaultConfig, the stdinReader no-TTY behavior, and every run() output mode (default, -1, -2, -C, -j, -A, -a). PuppetDB is stubbed with httptest — no live Consul/PuppetDB access is required.

Gotchas

• -1, -2, -C, and -A all require -R or -F; the tool exits with an error otherwise.
• -C (count) with stdin reads all lines as pre-fetched "node value" output for counting — it does not query PuppetDB per line.
• JSON output (-j) builds { hostname: { factname: value } } where the fact key is the -F value, the role_fact config value (if -R), or "value" as fallback.
• config init fails if the config file already exists (will not overwrite).