Add instructions to run stack with an external L1 chain

stack/fixturenet-optimism/README.md

@@ -2,6 +2,8 @@
 
 Instructions to setup and deploy an end-to-end L1+L2 stack with [fixturenet-plugeth](https://git.vdb.to/cerc-io/stack-orchestrator/src/branch/main/stack_orchestrator/data/stacks/fixturenet-plugeth) (L1) and [Optimism](https://stack.optimism.io) (L2)
 
+We support running just the L2 part of stack, given an external L1 endpoint. Follow the [L2 only doc](./l2-only.md) for the same.
+
 ## Setup
 
 Clone the stack repo:
@@ -119,8 +121,8 @@ laconic-so deployment --dir fixturenet-plugeth-deployment start
 laconic-so deployment --dir fixturenet-optimism-deployment start
 ```
 
-1. The `fixturenet-eth` L1 chain will start up first and begin producing blocks.
+1. The `fixturenet-eth` L1 chain will start up first and begin producing blocks
-2. The `fixturenet-optimism-contracts` service will configure and deploy the Optimism contracts to L1, exiting when complete. This may take several minutes; you can follow the progress by following the container's logs (see below).
+2. The `fixturenet-optimism-contracts` service will configure and deploy the Optimism contracts to L1, exiting when complete. This may take several minutes; you can follow the progress by following the container's logs (see below)
 3. The `op-node` and `op-geth` services will initialize themselves (if not already initialized) and start
 4. The remaining services, `op-batcher` and `op-proposer` will start
 

stack/fixturenet-optimism/l2-only.md

@@ -0,0 +1,130 @@
+# fixturenet-optimism (L2-only)
+
+Instructions to setup and deploy L2 fixturenet using [Optimism](https://stack.optimism.io)
+
+Prerequisite: An L1 Ethereum RPC endpoint (with unprotected txs enabled)
+
+## Setup
+
+Clone the stack repo:
+
+```bash
+laconic-so fetch-stack git.vdb.to/cerc-io/fixturenet-optimism-stack
+```
+
+Clone required repositories:
+
+```bash
+laconic-so --stack ~/cerc/fixturenet-optimism-stack/stack/fixturenet-optimism setup-repositories
+
+# If this throws an error as a result of being already checked out to a branch/tag in a repo, remove concerned repositories and re-run the command
+```
+
+Build the container images:
+
+```bash
+laconic-so --stack ~/cerc/fixturenet-optimism-stack/stack/fixturenet-optimism build-containers
+```
+
+This should create the required docker images in the local image registry:
+* `cerc/optimism-contracts`
+* `cerc/optimism-l2geth`
+* `cerc/optimism-op-node`
+* `cerc/optimism-op-batcher`
+* `cerc/optimism-op-proposer`
+
+## Create a deployment
+
+First, create a spec file for the deployment, which will map the stack's ports and volumes to the host:
+
+```bash
+laconic-so --stack ~/cerc/fixturenet-optimism-stack/stack/fixturenet-optimism deploy init --map-ports-to-host any-fixed-random --output fixturenet-optimism-spec.yml
+```
+
+### Ports and Data volumes
+
+The default port and volume mappings to host can be customized by editing the "spec" file generated by `laconic-so deploy init`
+
+---
+
+Once you've made any needed changes to the spec file, create a deployment from it:
+
+```bash
+laconic-so --stack ~/cerc/fixturenet-optimism-stack/stack/fixturenet-optimism deploy create --spec-file fixturenet-optimism-spec.yml --deployment-dir fixturenet-optimism-deployment
+```
+
+## Set chain env variables
+
+Inside the deployment directory, open the file `config.env` and add the following variables to point the stack at your L1 rpc and provide account credentials ([defaults](../../config/fixturenet-optimism/l1-params.env)):
+
+  ```bash
+  # External L1 endpoint
+  CERC_L1_CHAIN_ID=
+  CERC_L1_RPC=
+  CERC_L1_HOST=
+  CERC_L1_PORT=
+
+  # URL to get CSV with credentials for accounts on L1
+  # that are used to send balance to Optimism Proxy contract
+  # (enables them to do transactions on L2)
+  CERC_L1_ACCOUNTS_CSV_URL=
+
+  # OR
+  # Specify the required account credentials for the Admin account
+  # Other generated accounts will be funded from this account, so it should contain ~20 Eth
+  CERC_L1_ADDRESS=
+  CERC_L1_PRIV_KEY=
+  ```
+
+* NOTE: If L1 is running on the host machine, use `host.docker.internal` as the hostname to access the host port, or use the `ip a` command to find the IP address of the `docker0` interface (this will usually be something like `172.17.0.1` or `172.18.0.1`)
+
+## Start the stack
+
+Start the deployment:
+
+```bash
+laconic-so deployment --dir fixturenet-optimism-deployment start
+```
+
+1. The stack will check for a response from the L1 endpoint specified in your env file
+2. The `fixturenet-optimism-contracts` service will configure and deploy the Optimism contracts to L1, exiting when complete. This may take several minutes; you can follow the progress by following the container's logs (see below)
+3. The `op-node` and `op-geth` services will initialize themselves (if not already initialized) and start
+4. The remaining services, `op-batcher` and `op-proposer` will start
+
+### Logs
+
+To list and monitor the running containers:
+
+```bash
+laconic-so --stack fixturenet-optimism deploy ps
+
+# With status
+docker ps
+
+# Check logs for a container
+docker logs -f <CONTAINER_ID>
+```
+
+## Example
+
+Try out the [example](./README.md#example-bridge-some-eth-from-l1-to-l2) to bridge ETH from L1 to L2
+
+Note: Use external L1 endpoint as `L1_RPC` and add flag `--add-host="host.docker.internal:host-gateway"` to `docker run` commands if necessary
+
+## Clean up
+
+To stop all L2 services running in the background, while preserving chain data:
+
+```bash
+laconic-so deployment --dir fixturenet-optimism-deployment stop
+```
+
+To stop all L2 services and also delete chain data:
+
+```bash
+laconic-so deployment --dir fixturenet-optimism-deployment stop --delete-volumes
+```
+
+## Troubleshooting
+
+See [Troubleshooting](./README.md#troubleshooting)