snyball / tombl

Easily query TOML files from bash

tombl

tombl makes bash viable for DevOps-automations that involve configurations saved as .toml files.

$ eval "$(tombl -e DB=databases.hmm /etc/my-config.toml)"
$ echo "${DB[user]}"
postgreker
$ pg_dumpall -h "${DB[host]}" -p "${DB[port]}" -u "${DB[user]}" > out.sql
$ eval "$(tombl -e KEYS=backup.gpg_keys /etc/my-config.toml)"
$ for key in "${KEYS[@]}"; do echo "key: $key"; done
key: [e-mail]
key: [e-mail]

It allows bash to read .toml files structurally, so you don't have to come up with weird ad-hoc solutions involving awk, sed, and tears as soon as it breaks in production because you didn't use an actual toml-parser. It does this by outputting declare statements for associative, and "plain" arrays.

$ tombl -e DB=databases.hmm /etc/my-config.toml
declare -A DB=([user]=postgreker [password]='super secret' [host]=0.0.0.0 [port]=5432)

$ tombl -e GPG_KEYS=backup.gpg_keys /etc/my-config.toml
declare -a GPG_KEYS=([e-mail] [e-mail])

$ tombl -e VAR=some.number /etc/my-config.toml
declare -i VAR=123

$ tombl -e VAR=some.thing /etc/my-config.toml
declare VAR='a thing of sorts'

Bash is unable to store nested arrays of any kind, so any nesting will be ignored when exporting, and you'll have to adapt your -e VAR=path.to.thing to access the nested information. It is recommended that you start your scripts with set -euo pipefail in order to fail fast™.

$ set -euo pipefail
$ cat /etc/my-config.toml
[databases.hmm]
user = "postgreker"
password = "super secret"
host = "0.0.0.0"
port = 5432
thing-that-is-nested = { will-not-be-included = 123 }
$ tombl -e DB=databases.hmm /etc/my-config.toml
declare -A DB=(["user"]="postgreker" ["password"]="super secret" ["host"]="0.0.0.0" ["port"]=5432)
$ eval "$(tombl -e DB=databases.hmm /etc/my-config.toml)"
$ echo "${DB[thing-that-is-nested]}" # whoops, but this will fail fast because of `set -euo`
bash: l: unbound variable

The tombl binary is 184K statically linked, and the release build is created with the help of itself in make-release.sh. Builds are available for Linux only, but it should work on any platform Rust supports.