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Self-Cert

Mint your own self-signed TLS certificates with pg cert and serve them from the store addons

Why self-sign

Two addons that speak S3 over TLS — minio, silo, rustfs — can serve certificates two ways:

Generated (--tls): pgcli mints a self-signed CA + leaf for you, owns the cert dir, and refreshes it on restart. Zero setup, fixed SANs.
Bring-your-own (--tls-cert / --tls-key): you supply the pair. This is where a public CA cert, a wildcard you already hold, or a cert with custom SANs goes.

pg cert is the mint for the second path: it creates a self-signed certificate whose SANs cover exactly the hostnames and IPs you need, so you can try BYO TLS without a real CA — and it writes them as a standalone pair, not registered with pgcli: the files go wherever you point them, pg.yaml is untouched, and no container is started. Hand them to a store with --tls-cert/--tls-key yourself.

Quick start

# A directory to hold the pair (any writable path works; keep it out of the
# data dir). pgcli's base dir already lives under ~/.pgcli:
mkdir -p ~/.pgcli/certs

# A leaf valid for one DNS name and two IPs, ECDSA P-256, 825 days (defaults):
pg cert --host "rustfs.test,127.0.0.1,10.0.0.9" \
  --cert-file ~/.pgcli/certs/rustfs.crt \
  --key-file  ~/.pgcli/certs/rustfs.key

# Serve it from a store (any of the three), giving the full paths:
pg addon install rustfs --name store \
  --tls-cert ~/.pgcli/certs/rustfs.crt \
  --tls-key  ~/.pgcli/certs/rustfs.key

pg cert prints the SANs it wrote and nothing else — it is a pure file generator, not an addon command.

Flags

Flag	Default	Meaning
`--host`	`127.0.0.1`	Comma-separated DNS names and/or IPs to encode as SANs (repeatable). Entries are auto-detected as one or the other, so `"rustfs.test,10.0.0.9"` needs no special syntax; `*.wild.test` works as a wildcard DNS entry.
`--cert-file`	`cert.pem`	Path to write the PEM certificate.
`--key-file`	`key.pem`	Path to write the PEM private key (PKCS8, mode `0600`).
`--valid-duration`	`825` days	How long the cert stays valid, e.g. `--valid-duration 8760h` for a year.
`--ecdsa`	`P-256`	Curve: `P-224`/`P-256`/`P-384`/`P-521`. Set to `""` to disable ECDSA (and pair with `--rsa`).
`--rsa`	(off)	RSA key size (e.g. `2048`, `4096`); set only when you specifically need RSA instead of the default ECDSA key.
`--ca`	`false`	Make the cert its own CA (`CA:TRUE`, `keyCertSign`) — for when you want a private root to sign further certs with, not the usual case for `--tls-cert`.

The same generator is built as a standalone binary for use outside pg — make gencert → bin/gencert, with the identical flag set in single-dash form (-host, -cert-file, …). Both front one package, so their output is the same kind of certificate byte-for-byte.

What `pg cert` writes

One self-signed leaf, not a chain. The PEM in --cert-file holds exactly one CERTIFICATE block — the cert signs itself (CA:FALSE, serverAuth EKU, your SANs). There is deliberately no leaf+intermediate+root bundle: there is no issuing CA above it, so there is nothing to chain.

This is also why the --ca output is not something to point --tls-cert at: pg addon install … --tls-cert runs ValidateBYOCert, which inspects the first certificate and rejects one that is a CA. The --ca cert is a trust anchor you sign others with, not a server cert to serve.

Using it as the client’s trust anchor

Because the result is self-signed, hand the same .crt to every TLS client as its CA file — the served leaf is its own trust anchor. For pgBackRest’s S3 repository that means pointing --s3-ca-file at the pg cert output directly:

pg backup setup --s3-endpoint <store-host>:<api-port> \
  --s3-ca-file /path/to/rustfs.crt

This is not a workaround pgBackRest merely tolerates: OpenSSL treats whatever you hand it as an anchor (CA:TRUE not required), and pgBackRest’s S3 TLS path is that same mechanism. Verified directly: openssl verify -CAfile <cert> <cert> on the self-signed CA:FALSE leaf returns OK.

To place the cert on a host that dials the store without shipping the file, use pg backup fetch-ca — it pulls the issuing cert straight out of the live TLS handshake.

Serving it from a store

The three S3 stores each mount your pair under the filenames their binary requires, so your filenames are free — pg cert --cert-file anything.crt works for all three:

# MinIO / silo read public.crt + private.key:
pg addon install minio --name store --tls-cert anything.crt --tls-key anything.key
pg addon install silo  --name store --tls-cert anything.crt --tls-key anything.key

# rustfs reads rustfs_cert.pem + rustfs_key.pem:
pg addon install rustfs --name store --tls-cert anything.crt --tls-key anything.key

pgcli never re-owns or writes to your source files; in rustfs’s case the pair is mounted read-only and copied into the container’s own cert dir (see rustfs → Privileges and ownership).

Verified on rustfs

On a real install, a pg cert leaf served by rustfs was confirmed off the live TLS handshake (subject == issuer on the cert actually presented, not just what pg.yaml recorded), the container came up healthy over HTTPS, and pg mc completed a full alias set → mb → put → ls → get round-trip against it with the fetched object byte-identical to the one uploaded.

Renewing a BYO cert

A single-file bind mount pins the source inode, so replacing the file in place does not take effect on a running container. To renew, mint a fresh pair (or overwrite the files), then recreate:

pg cert --host "rustfs.test,127.0.0.1" --cert-file rustfs.crt --key-file rustfs.key
pg addon install rustfs --name store \
  --tls-cert rustfs.crt --tls-key rustfs.key --force

Turning BYO off (fall back to the generated pair, or plain HTTP): delete the cert_file/key_file lines for that addon in pg.yaml and --force a recreate.