docs: how to run relayer via local devnet

Adds some docs on maintenance tasks and common testing procedures.
Links out to information elsewhere, just making it discoverable via the
relayer README.

Refs #465, #2252.

.gitignore

@@ -35,3 +35,7 @@ target/
 
 # Ignoring lock file for the parameter-setup tool.
 tools/parameter-setup/Cargo.lock
+
+# Relayer config referencing local devnet, will always be unique
+# to current host env.
+deployments/relayer/configs/penumbra-local.json

deployments/relayer/README.md

@@ -17,6 +17,18 @@ Or, you can use `just` to run it all, soup to nuts. See the path configuration
 block in the `./configure-relayer` script for some example paths between chains
 that aren't yet known to work.
 
+## Updating proto definitions in relayer
+Sometimes the protos between preview & testnet get out of sync. When this happens,
+we must submit a PR upstream to the relayer repo. See [example here](https://github.com/cosmos/relayer/pull/1170),
+along with instructions on the commands to generate the protos for the golang repo.
+Until the protos are back in sync, relaying between Penumbra chains may not work.
+
+## Running a local devnet
+By default the relayer scripts configure a path between testnet and preview.
+For debugging, it can be useful to use a path between a local devnet and preview,
+potentially even on the same git commit. See the instructions in [GH 2252](https://github.com/penumbra-zone/penumbra/issues/2252)
+for details on how to set it up. You may need to edit the chain ids in `./configure-relayer`.
+
 ## Further reading
 The config format for the JSON files are adapted from the [example-configs](https://github.com/cosmos/relayer/tree/main/docs/example-configs)
 in the relayer repo. Our configs will get out of date very quickly: the preview chain id changes

deployments/relayer/generate-configs

@@ -3,7 +3,7 @@ set -euo pipefail
 
 
 if [[ $# -lt 1 ]] ; then
-    >&2 echo "ERROR: no network declared. Use either 'testnet' or 'preview'."
+    >&2 echo "ERROR: no network declared. Use one of: testnet, preview, or local."
     >&2 echo "Usage: $0 <network>"
     exit 1
 fi